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Dermatopathology > Dermatopathology - Entities & Features > Flashcards

Dermatopathology - Entities & Features Flashcards

1
Q

Clear cell acanthoma

A

Clear demarcation from epidermis
Often neutrophils present
PAS + showing abundant glycogen

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2
Q

Poroma

A 
Small monomorphic cells 
Epidermis ‘raining down’ 
Sharp demarcation of epidermis to dermis
Glandular structures in dermis
Connected to basal layer of epidermis
Forms vertically oriented columns
Ductal spaces
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3
Q

Trichilemmoma

A

Acanthosis in epidermis
Eyeliner sign / peripheral palisade
Some koilocytic like changes at edges of lesion
Clear cell change due to glycosylation of cytoplasm
Overlying hypergranulosis and hyperkeratosis

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4
Q

Fibroepithelioma of pinkus

A

Fenestrated strands off epidermis
BCC like areas in scaffold
PHLDA1 marker - less staining in basaloid areas , more staining in pink areas

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5
Q

Tumour of follicular infundibulum

A

Epidermal epithelial growth with a plate like configuration and multiple connections to the epidermis
- keratinocytes have glycogenated appearance resembling those of outer root sheath
Prominent surrounding basement membrane

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6
Q

Elastosis perforans serpinosa

A
  • extrusion of elastin fibres / transepidermal elimination
  • associated folliculitis
  • can have overlying parakeratosis with neuts
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7
Q

Folliculitis de calvans

A 
Plasma cells
Polytrichia
Scarring fibrosis 
Neutrophilic abscesses 
Hair shaft granulomas 
Lymphocytes
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8
Q

Granular cell tumour

A

Overlying epidermis may show pseudoepitheliomatous hyperplasia
Proliferation of large to polygonal cells with granular eosinphilic cytoplasm in sheets
Individual cells with indistinct borders, small round centrally located nuclei
Large eosinophilic
S100 +ve
CD68 +ve

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9
Q

Syringocystadenoma papilliferum

A

CYSTIC neoplasm opening into surface
Epidermis has hyperplasia and papillomatosis
Tumour shows papillary growth pattern with papillae composed of FIBROVASCULAR CORE surrounded by 2 layers of cells — inner tall columnar cells with eosinophilic cytoplasm
Plasma cells conspicuous
Look for associated sebaceous naevus

DDx: hydrocystadenoma, hydradenoma, hidradenoma papilliferum,

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10
Q

Granuloma annulare

A 
Closed off palisading granulomas
Upper third epidermis
Granulomatous inflammation 
Mucin stain positive (colloidal iron, alcian blue)
Normal dermis visible
Eosinophils
Multinucleated giant cells
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11
Q

Acantholytic acanthoma

A

Papillomatosis, epidermal hyperplasia with overlying hyperkeratosis

Prominent acantholysis throughout epidermis

Mild superficial perivascular infiltrate

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12
Q

Acute generalised exanthematous pustulosis

A

Subcorneal or superficial intraepidermal neutrophilic pustules with admixed few acantholytic keratinocytes
Background spongiosis with neutrophilic exocytosis and scattered dyskeratotic cells
Papillary dermal oedema
Perivascular mixed inflammatory infiltrate

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13
Q

Dermatofibroma aka fibrous histiocytoma

A
  • Epidermal hyperplasia with flattened rete ridges ,
  • Basal induction - induction follicles and sebaceous glands
  • Poorly circumscribed proliferation of spindled and/or epithelioid fibroblasts and histiocytes
  • Multinucleated giant cells - touton like
  • Xanthomatised histiocytes
  • Cellular dermis with collagen entrapment more prominent at periphery
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14
Q

Pilomatricoma

A
  • Multinodular tumour in dermis and/or subcutis composed of nests resembling those of the hair matrix with abrupt transition to central shadow cells
  • calcifications and foreign body granulomatous response
  • numerous mitotic figures
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15
Q

Sebaceous adenoma

A

Nodular sebaceous and basaloid proliferation
Broadly connected to epidermis
Predominance sebaceous glands
Minimal cytological atypia

Erosion overlying is commmon
More mature sebocytes over less differentiated blue cells
Lipidized cells

MMR gene mutations MSH2, MSH6, PMS2, MLH1

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16
Q

T/F viral cytopathic change going down hair follicles is more likely VZV than HSV

A

True

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17
Q

Palisaded encapsulated neuroma

A

Well circumscribed but non encapsulated
Usually cleft but no capsule
Spindled cells wavy nuclei
Mast cells present

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18
Q

Bullous arthropod bite reaction

A

Subepidermal bulla ,
eos predominate
Superficial and deep eosinophilic infiltrate

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19
Q

Cylindroma

A

Jig saw arrangements of basaloid islands
Two cell populations small basaloid cells periphery and larger pale cells centrally
Eosinophilic aggregates within nests and around nests forming stroma

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20
Q

What is a sunburn cell

A

Single or few apoptotic cells high up in epidermis

Consistent with a photodermatosis

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21
Q

Polymorphous light eruption

A

Variable epidermal spongiosis with dyskeratosis
Superficial and deep mixed inflammation (mostly lymphocytic)
Red cell extravasation
Marked papillary dermal oedema

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22
Q

Chronic cutaneous lupus erythematosus

A

Follicular plugging
BM thickening
Lichenoid reaction pattern - basal vacuolation and apoptotic keratinocytes
Superficial and deep lymphocytic infiltrate
Mucin interstitially

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23
Q

Lupus tumidus

A

Relative sparing of epidermis
Superficial and deep lymphocytic inflammation
Mucin deposition interstitially

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24
Q

Subacute cutaneous lupus erythematosus

A 
CF. DLE
- presence of more epidermal atrophy
- epidermal atrophy 
Basement membrane thickening
Mucin deposition 
Superficial and deep lymphocytic infiltrate with periappendegeal spread /peri-eccrine 
- Less hyperkeratosis
- Less Basement membrane thickening
- Less follicular plugging
- Less inflammatory infiltration
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25
Q

Lesions with keratin horn

A

Seb K
AK
IEC
SCC

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26
Q

Lichen planopilaris

A

Usually 8 pilosebaceous follicles in each mm of biopsy
Thus 36 or more follicles normal in a 4mm scalp biopsy

  • lichenoid band like infiltrate with interface changes involving follicular infundibulum, concentric lamellar fibroplasia
  • interfollicular epidermis usually spared
  • loss of sebaceous glands and follicles
  • DIF nonspecific cytoid bodies positive for IgM
  • fusion of hair follicles - in LPP not lupus
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27
Q

Traumatic neuroma

A
  • Proliferation of small bundles of well delineated nerve fascicles in a fibrotic stroma

STAIN: S100 for Schwann cells

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28
Q

Blastomycosis like pyoderma

A

Hyperplasia
Neutrophils
No evidence fungal/hyphae/

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29
Q

Sebaceous adenoma

A

Sebaceous lobule like structures
Peripheral basaloid cells (germinative cells) not more than >50%
need DNA mismatch repair markers

Cf. Sebaceoma - more disorganised, do not always retain the architecture; sebaceous duct like structures more prominent in sebaceoma

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30
Q

Mixed tumour of the skin

Chondroid syringoma

A

Circumscribed nodule
Clear cut cartilage with bluish appearance
Myxochondroid change, looks like cells are sitting in lacunae
Elongated , curved atubular structures
Rounded ductal structures / sometimes cystic structures

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31
Q

Lichen sclerosus

A 
Hyperkeratosis
Epidermal atrophy
Some lichenoid change 
Follicular plugging
Homogenised collagen [papillary dermis
Underlying band like infiltrate
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32
Q

Adamantinoid trichoblastoma

A

Small nests with peripheral palisade — clear cells in middle not sebaceous origin

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33
Q

Warty dyskeratoma

A

Solitary cup shaped focus with acantholysis and dyskeratosis

DDx:
Acantholytic acanthoma — no dyskeratosis
Old lesions of Grover’s - can be proliferative/atypical
Comedonal Darier

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34
Q

Palisaded encapsulated neuroma

A

Fascicular arrangement of Schwann cells- often separated by small clefts with neural/wavy nuclei with pointed polar ends
- no dysplasia
- can see some nuclear palisading
- often has artefactual change like BCC where tumour separates from dermis
- no clear capsule or thin capsule only
s100 positivity
Ddx: NF, Pilar leiomyomas

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35
Q

Verruca (deep plantar wart)

A

Church spire like hyperkeratosis

See inclusion like keratohyalin

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36
Q

Diameter of microscope field Olympus microscope

A

11mm at x2 power

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37
Q

Secondary syphilis

A

Numerous plasma cells, superficial and deep
Lichenoid reaction pattern or psoriasiform reaction pattern with long thin rete
Endothelial cell swelling

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38
Q

Halo naevus

A

Regression in naevus
Lichenoid reaction centrally
Dense admixed lymphocytes in the upper dermis

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39
Q

Venous lake

A

Large dilated channel containing erythrocytes with thin endothelial lining with thin fibrosis
Dilated capillary/venule
Can be thrombosed secondary to trauma

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40
Q

Thrombophlebitis

A

Thrombosis within a thick walled lumen within the subcutaneous fat
Ddx: erythema induratum
Polyarteritis nodosa

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41
Q

Clear cell acanthoma

A

Well demarcated acanthotic epidermis with pale/clear cells, overlying parakeratosis and may co-exist with a prurigo nodule

—> PAS, followed by PAS-diastase to remove glycogen

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42
Q

Blue naevus

A
  • Dendritic melanophages and spindled melanocytes
  • Spindled cell proliferation, spindled melanocytes look like angulated cells with processes
  • Often arranged around a follicular structure
  • Pigment throughout lesion
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43
Q

Spitz naevus

A

Plump epithelioid nests
Vertical orientation of nests in papillary dermis
Doesn’t always have Kamino bodies

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44
Q

Juvenile xanthogranuloma

A

Sheet like nodular aggregates of lymphocytes histiocytes and eosinophils with admixed touton giant cells
- admixed xanthomatous cells / foam change

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45
Q

Syringoma

A
  • Tadpole shaped eccrine structures in dermis forming tadpole-like structures
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46
Q

Phototoxic drug eruption

A

Intraepidermal blister with neutrophils

Epidermal necrosis

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47
Q

Pyogenic granuloma

A

Exophytic vascular nodule
Lobulated capillary network
Epidermal collarette
Neutrophils correlate with degree of ulceration

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48
Q

Polymorphic eruption of pregnancy

A

Nonspecific findings
— eosinophils with lymphocytic inflammation
— perivascular
— dermal oedema

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49
Q

Sebaceoma

A

Nodular sebaceous and basaloid proliferation

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50
Q

Nodular melanoma

A
  • Prominent vertical growth phase
  • few mitotic figures
  • check peripheries in case arising in melanoma in situ
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51
Q

Ashy dermatosis

A

Lichenoid reaction pattern
Pigment incontinence
Upper dermal inflammation (lymphocytes/eosinophils)

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52
Q

Angioleiomyoma

A
  • ## Discrete nodule in dermis of smooth muscle spindle cells arranged into fascicles
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53
Q

Lichen striatus

A

Combination of 2 reaction pattern in epidermis - spongiosis and lichenoid
— peri-eccrine lymphocytic infiltration

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54
Q

Clear cell hidradenoma

A
  • solid and cystic areas with scattered ducts

DDx. poro-hidradenoma , many poroid cells

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55
Q

Mastocytosis

A

— Increase in mast cells

— look at proportion of mast cells to lymphocytes

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56
Q

Cellular Dermatofibroma

A

DF - CD13a positive, CD34 neg

Vs. DFSP - CD34 positive, CD 13a neg

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57
Q

Erythrasma

A

Corynebacterium - gram pos bacilli in s. Corneum

Pagetoid dyskeratosis

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58
Q

Urticaria

A

Neuts in vessel wall
Dermal oedema
Polymorphous infiltrate

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59
Q

Epidermolytic acanthoma

A

Hyperkeratosis
Slightly endophytic
Coarse granules
VACUOLATED cytoplasm with eosinophilic globules

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60
Q

Granulomatous pigmented purpuric dermatosis

A

Granulomas in upper papillary dermis
Haemosiderin deposition
Papillary dermis filled with lymphocytes and histiocytes

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61
Q

Hypertrophic lichen planus

A

Lichenoid reaction in rete ridges

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62
Q

Extramammary Paget’s disease

A

Intraepidermal proliferation with predominantly single cells with admixed nests throughout the epidermis
- individual cells are large with amphophilic cytoplasm, large nucleus and prominent nucleoli
CK7, CEA, Cam5.2, S100 - likely primary EMPD

  • CK20, CEA, CAM5.2 positive, CK7, S100
    CK20 positive == urothelial origin
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63
Q

VZV blister

A

More likely to have associated folliculitis

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64
Q

Warty dyskeratoma

A

Cup shaped invagination with overlying hyperkeratosis and parakeratosis

  • acantholytic dyskeratosis of the invaginating epidermis with scattered corp ronds and grains is noted
  • dermal papillae lined by basal cells resemble villi and project into the invagination
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65
Q

Glomus tumour

A

Solid, well circumscribed nodular proliferation of small monotonous cells with round central nucleus and eosinophilic cytoplasm around dilated blood vessels

  • no atypic
  • cell positive for SMA
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66
Q

Actinic keratosis

A

Variable keratinocytic atypia in lower layers of epidermis with overlying focal parakeratosis

  • alternating ortho and parakeratosis
  • “sail sign”
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67
Q

Lichen striatus

A

Lichenoid reaction pattern
Mixed spongiotic reaction pattern with lichenoid
- peri eccrine distribution

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68
Q

Sarcoidosis

A

Non caseating epithelioid granulomas in dermis and /or subcutaneous tissue with minimal lymphocytic infiltrate
- Schumann bodies or asteroid bodies present

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69
Q

Alopecia areata

A

Decreased anagen/telogen ratio (INCREASED TELOGEN HAIRS)
MORE CATAGEN HAIRS (AT LEAST 50% — R. MORTIMORE)
- sparse lymphocytic infiltrate around hair bulbs (swarm of bees) with admixed eos
- fibrous tracts seen with pigment incontinence +/- pigment casts

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70
Q

Traumatic fat necrosis

A

Lobular panniculitis

Fat necrosis , suppurative and granulomatous response

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71
Q

Erythema elevatum diutinum

A

NODULAR DENSE MIXED INFILTRATE WITH PREDOMINANT NEUTROPHILS AND LYMPHOCYTES, PLASMA CELLS, LCV. Fibrosis and lipid deposits in late lesions. May or may not have grenz zone

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72
Q

Trichotillomania

A 
Peripilar haemorrhage
Trichomalacia
Pigment casts
Lymphocytic infiltrate 
Increased catagen hairs
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73
Q

FOLLICULITIS DE CALVANS

A

Dense infiltrate of neutrophils and plasma cells surrounding ruptured follicular units

  • follicular plugging and intra/perifollicular neutrophilic infiltrates
  • neutrophilic abscesses and hair shaft granulomas in dermis with admixed lymphocytes, histiocytes
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74
Q

Acne keloidalis nuchae

A

Perifollicular lymphoplasmacytic infiltrate with neuts
- follicle rupture, hair shaft granulomas assoc. with suppurative inflammation and dermal fibrosis
Sinus tracts common

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75
Q

Deep penetrating naevus

A

Symmetric compound melanocytic proliferation , extends to lower reticular dermis and SC fat in wedge shaped pattern .
Nuclei small with hyperchromasia
—> extend down adnexae
—> stains with cyclin D1 - has had mutation in common with melanoma pathway

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76
Q

Desmoplastic trichoepithelioma

A

Cords and strands forming dermal proliferation ,
Angiomyxoid stroma
Dystrophic calcification

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77
Q

Microcystic adnexal carcinoma

A
  • narrow, deeper islands with ductal differentiation
  • stratified growth pattern with microcyst in upper portion and smaller nests and single cells at base
  • invasion deep into subcutis (less likely syringoma)
  • when around eye, have more prominent hyalinised stroma
  • aka sclerosing sweat duct carcinoma
    Polyclonal CEA stain - around eccrine ducts
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78
Q

Spindle cell SCC

A
  • composed of partially or predominantly Atypical spindled cells in whorls or intersecting fascicles
  • prominent mitoses
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79
Q

Angiokeratoma

A

Intermixed dilated vessels with acanthotic epidermis

Hyperkeratosis

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80
Q

Pseudoxanthoma elasticum

A

Wavy shortened elastic fibres in dermis
Stain: VVG, von kossa for calcium
Pseudo-PXE induced by penicillamine does not have calcium

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81
Q

Chondrodermatitis nodularis helicus

A
  • narrow ulceration
  • fibrin and necrosis above level of cartilage
  • surrounding acanthosis
    Granulation tissue, fibrosis in dermis below the ulceration
  • sometimes transepidermal elimination of cartilage
  • cartilage if seen - can show degenerative changes
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82
Q

Morphoea profunda

A

Sclerotic collagen diffusely
Extending down to SC fat - septal panniculitis
Eccrine glands high riding
Loss of peri-eccrine fat

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83
Q

Collagenous and Elastotic marginal papules and plaques of the hand

A
  • ## Thickened, vertically oriented collagen bundles with foci of calcification
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84
Q

Stains for sebaceous neoplasm

A

Adipophilin, EMA, MSH2, MSH6, MSH1, PMS2,

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85
Q

Lesions with pagetoid spread

A 
Melanoma 
Merkel cell ca
IEC
SCC
AK 
EMPD
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86
Q

Amyloidosis

A

Melanophages
Globular deposits of eosinophilic material with clefting
STAINS: crystal violet aka methyl violet - changes to magenta (metachromatic stain), Congo red, thioflavin T

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87
Q

Pityriasis versicolor

A

Distinct cell wall rather than artefact with poor edges
Spores and hyphae
PAS+
Does not enter the epidermis, only the stratum corneum

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88
Q

Photoaggravated drug eruption

A
  • Dendritic cells in the dermis
  • mild spongiosis due to acute on chronic reaction
  • sunburn cells in the epidermis
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89
Q

Granular cell tumour

A

Can have malignant subtype

  • proliferation of large to round polygonal cells with granular eosinophilic cytoplasm in sheets
  • individual cells show indistinct borders, small round centrally located nuclei
  • large eosinophilic cytoplasmic granules —> pustulo-ovoid bodies of Milan, positive

Stains: s100 positive, Cal-ritinene positive
Malignant subtype has Ki67

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90
Q

Pyogenic granuloma

A
  • Significant cellularity around the vessels

- lobulated collection of dilated capillaries

91
Q

Trichilemmoma

A

Endophytic proliferation of lobules with clear squamous cells

92
Q

Angiosarcoma

A

Poorly demarcated proliferation of anatomising blood vessels (cracked collagen pattern) - and solid areas. Vessels show atypical spindled or epithelioid endothelial cells with multilayering and papillary structures - solid areas show sheets of spindled cells

93
Q

EMPD STAINS

A

CEA, EMA, CK7

  • mucicarmine
  • CAM5.2
  • CK20, GCDFP-15
94
Q

PROGNOSTIC FEATURES OF SCC

A
  • distance from tumour margin
  • PNI
  • LVI
  • Clark level
  • diameter >2mm
  • site
    Depth 2mm
  • recurrence
95
Q

Syringocystadenoma papilliferum

A

Cystic neoplasm opening onto surface. Epidermis shows hyperplasia and papillomatosis. Double cell wall layer

96
Q

Trichoepithelioma

A

CD34 positive stroma

Mesenchymal papillary body

97
Q

Eccrine spiradenoma

A

Basophilic circular populations with eosinophilic aggregates, two cell population, lymphocytes percolating through nests

98
Q

Pigmented spindle cell naevus of Reed

A

Junctional or compound (usually limited to papillary dermis) plaque like growth pattern with spindled melanocytes running parallel to epidermis

  • conspicuous melanin pigment
  • symmetrical configuration with sharp lateral borders no significant nuclear atypia
99
Q

Stains for sebaceous neoplasm

A

Adipophilin, EMA, MSH2, MSH6, MSH1, PMS2,

100
Q

Lesions with pagetoid spread

A 
Melanoma 
Merkel cell ca
IEC
SCC
AK 
EMPD
101
Q

Amyloidosis

A

Melanophages
Globular deposits of eosinophilic material with clefting
STAINS: crystal violet aka methyl violet - changes to magenta (metachromatic stain), Congo red, thioflavin T

102
Q

Pityriasis versicolor

A

Distinct cell wall rather than artefact with poor edges
Spores and hyphae
PAS+
Does not enter the epidermis, only the stratum corneum

103
Q

Photoaggravated drug eruption

A
  • Dendritic cells in the dermis
  • mild spongiosis due to acute on chronic reaction
  • sunburn cells in the epidermis
104
Q

Granular cell tumour

A

Can have malignant subtype

  • proliferation of large to round polygonal cells with granular eosinophilic cytoplasm in sheets
  • individual cells show indistinct borders, small round centrally located nuclei
  • large eosinophilic cytoplasmic granules —> pustulo-ovoid bodies of Milan, positive

Stains: s100 positive, Cal-ritinene positive
Malignant subtype has Ki67

105
Q

Pyogenic granuloma

A
  • Significant cellularity around the vessels

- lobulated collection of dilated capillaries

106
Q

Trichilemmoma

A

Endophytic proliferation of lobules with clear squamous cells

107
Q

Angiosarcoma

A

Poorly demarcated proliferation of anatomising blood vessels (cracked collagen pattern) - and solid areas. Vessels show atypical spindled or epithelioid endothelial cells with multilayering and papillary structures - solid areas show sheets of spindled cells

108
Q

EMPD STAINS

A

CEA, EMA, CK7

  • mucicarmine
  • CAM5.2
  • CK20, GCDFP-15
109
Q

PROGNOSTIC FEATURES OF SCC

A
  • distance from tumour margin
  • PNI
  • LVI
  • Clark level
  • diameter >2mm
  • site
    Depth 2mm
  • recurrence
110
Q

Syringocystadenoma papilliferum

A

Cystic neoplasm opening onto surface. Epidermis shows hyperplasia and papillomatosis. Double cell wall layer

111
Q

Trichoepithelioma

A

CD34 positive stroma

Mesenchymal papillary body

112
Q

Eccrine spiradenoma

A

Basophilic circular populations with eosinophilic aggregates, two cell population, lymphocytes percolating through nests

113
Q

Pigmented spindle cell naevus of Reed

A

Junctional or compound (usually limited to papillary dermis) plaque like growth pattern with spindled melanocytes running parallel to epidermis

  • conspicuous melanin pigment
  • symmetrical configuration with sharp lateral borders no significant nuclear atypia
114
Q

Sweet syndrome

A

Epidermis normal
Marked papillary Dermal oedema
Florid neutrophilic inflammatory infiltrate with karyorrhexis
- true vasculitis can present focally

— Gossamer strands

DDx: pustular vasculitis
Rheumatoid neutrophilic dermatosis, BADAS, Behcet’s

115
Q

Sebaceoma

A

Nodular Basaloid nests with sebaceous differentiation
Minimal cytologic atypia
Basaloid cells predominant >50%

STAINS: MSH2, MSH6, PMS2, MLH1 , adipophilin

116
Q

Digital myxoid cyst

A

Localised deposit of mucin in cystic space
Cyst without any specific lining
— mucin stains: colloidal iron , alcian blue

117
Q

Porokeratosis

A

normal basket-weave stratum corneum
No neutrophils
Vertical column of parakeratosis - cornoid lamella
Underlying hypogranulosis, focal thinning of epidermis with scattered dyskeratotic cells

118
Q

Desmoplastic trichoepithelioma

A

Well demarcated discrete dermal lesion
Narrow cords and strands of compact epithelial cells and keratinous microcyst in a background of dense and collagenous sclerotic stroma

  • BCC has high + staining for BCl-2
  • BCl-2 also good for differentiating between inflamed Seb K and SCC (more positive in inflamed SebK)
  • TE is positive for CK20 whilst a BCC is negative for CK20
119
Q

Blue naevus

A

pigmented spindle cell proliferation

Dendritic melanophages in setting of sclerotic stroma

120
Q

Lentigo maligna melanoma

A

Proliferation of atypical melanocytes at DEJ as confluent proliferation of single cells and nests

  • extends along adnexal structures
  • pagetoid spread within epidermis throughout the lesion
  • eosinophilic stroma displaces solar elastosis
121
Q

Bullous pemphigoid

A

Subepidermal cellular bullae —.eosinophils, neutrophils , lymphocytes
DDx: EBA, bullous arthropod bite reaction, bullous drug

Cf.
EBA - 1. vesiculation can involve adnexae unlike BP
2. More neutrophils

122
Q

Keratoacanthoma

A
  • Large glassy keratinocytes forming sheets
  • Associated with pseudohorn cysts
  • Chronic inflammation and scarring
  • associated with multilayering of sweat ducts - syringometaplasia
123
Q

Neurofibroma

A

Variably circumscribed, non encapsulated proliferation of spindle cells with wavy nuclei, arranged haphazardly in a loose myxoid stroma
Scattered mast cells

Stains: s100 for Schwann cells positive, tryptase for mast cells m CD34 positive stroma

124
Q

Inverted follicular keratosis

A

Endophytic proliferation of squamous epithelium and basaloid cells with finger like projections into the dermis
Squamous eddies characteristically present at base
Mild lymphohistiocytic infiltrate in dermis

125
Q

Trichofolliculoma

A

Large central primary dilated follicular infundibulum with multiple small secondary hair follicles emptying into mother follicle
- cellular fibrous stroma in close approximation to the hair follicle

126
Q

Schwannoma

A

Encapsulated lesion in dermis and/or subcutis
Cellular areas composed of closely packed spindle cells with tapered wavy nuclei
- producing a palisading pattern (Antoni A)
Intermixed less cellular areas showing scattered spindle cells

No neurofilament - no axons
Positive neurofibromin

127
Q

Apocrine hydrocystoma

A

Unilocular or multilocular cystic cavity lined by TWO layers of epithelial cells with decapitate secretions in lumen

128
Q

Dermatofibroma

A 
Basal induction
Acanthotic and hyperpigmented basal layer
Spindled cell proliferation
papillary mesenchymal bodies
Sclerotic entrapment of collagen
129
Q

Mixed tumour of the skin

A

Well circumscribed biphasic tumour with admixed epithelial and mesenchymal components

Plasmacytoid
Dyscohesive solid masses of cells - myoepithelial cells

130
Q

Atypical genital naevus

A

Large atypical junctional nests

  • Stromal fibrosis/lamellar fibrosis
  • can be confused with melanoma
131
Q

PITYRIASIS VERSICOLOR

A

Spores and hyphae in stratum corneum

  • COMPARED TO DERMATOPHYTE INFECTION
    —> LESS SPONGIOTIC
    —> NO NEUTROPHILS
    —> no sandwich sign
132
Q

Atrophic epidermis only ~3 cells thick with lichenoid ddx

A

Dermatomyositis
Lupus
Porokeratosis

133
Q

Trichoadenoma

A

Small doughnut like proliferation of keratolytics composed of eosinphilic squamous cells with large central horn cysts. Fibroblastic stroma
Epidermal type keratinisation with granular layer

134
Q

HSV folliculitis

A
  • Sebaceous gland necrosis

- Neutrophilic debris

135
Q

Digital myxoid cyst

A

Localised deposit of mucin in cystic space

- cyst without specific lining

136
Q

Interface obscuring lichenoid dermatitis

A

Erythema multiforme (reticulated degenerative changes in late biopsy)
SJS/TEN
FDE (pigment incontinence, neutrophils in infiltrate)
PLEVA (parakeratosis, erythrocyte extravasation)
SCLE (follicular involvement, BM thickening, mucin)
GVHD
Adjacent herpes blister
paraneoplastic pemphigus (suprabasal acantholysis)
Acute lupus erythematosus

137
Q

Desmoplastic melanoma

A

SUBTLE proliferation of spindle cells in dermis with scattered atypical cells
- spindle cells may form fascicles in a fibrotic stroma
Perineural invasion often seen

S100 best, SOX-10 good too
HMB-45 , Melan-A can often be negative

138
Q

Fibroepithelioma of pinkus

A

Anastomosing thin strands of epidermis with fenestrated appearance
In setting of fibroblastic stroma

139
Q

Flegel disease

A

Hyperkeratosis with focal parakeratosis / papule has a discrete zone of ortho-hyperkeratosis contrast with normal epithelium

  • in the periphery the epidermis is acanthotic with colarette-like elongated rete ridges,
  • lymphocytic lichenoid infiltrate in early lesions
  • EM membrane coated granules (Odland bodies)
  • slight degree of hyperchromatic mood or nuclear infoldings - resembling Sezary cells, have been described in some cases of Flegel disease
140
Q

Schwannoma

A

Circumscribed encapsulated dermal nodule
Antoni A and B areas
Palisaded nuclei
Thickened vessel walls

141
Q

Vitiligo

A

Absence of melanocytes (halo cells)
Sparse inflammatory infiltrate
Epidermal atrophy
\STAINS: SOX-10, Melan-A, HMB-45, s100

142
Q

Discoid eczema

A 
Stratum corneum serum crust
Spongiosis of epidermis
Epidermotropism of lymphocytes
Eosinophils 
Drug induced spongiotic dermatitis - pityrisiaform spongiosis according to KC Chong
143
Q

HSV infection

A

Margination of chromatin
Steel gray nuclei
Nuclear dust
Intraepidermal vesicles - mixed inflammatory infiltrate: variable in HSV infection according to KC Chong (can have neuts, eos, or be monomorphic)

144
Q

Actinic keratosis

A

Parakeratotic changes in stratum corneum - compact hyperkeratosis, nuclear dysplasia
Sometimes acantholysis

145
Q

Pigmented spindle cell naevus of Reed

A

Spindled melanocytes run parallel to the epidermis
Junctional or compound plaque like growth pattern
Symmetrical configuration with sharp lateral borders
Younger patient — no solar elastosis

146
Q

Mycosis fungoides

A

Atypical lymphocytes giving rise to Pautrier microabscesses
Exocytosis of lymphocytes/epidermotropism (more atypical and larger than lymphocytes in the dermis)
Wiry collagen fibres
Single lymphocytes lining up against the Basement membrane zone
Atypical lymphocytes are surrounded by halos

147
Q

Mixed tumour of the skin/choroid syringoma

A

Circumscribed dermal nodule with two cell populations

Fibromyxoid stroma

148
Q

Mastocytosis

A

Cf normal mast cells
—> in mastocytosis, hypertrophic and clustered, more spindled
—> stains: tryptase is the most specific - CD117, toluidine blue (metachromatic change blue to purple)

149
Q

Trichilemmoma

A
  • Eosinophilic lobules with eyeliner sign - palisaded - has some incr pink cuticle/basement membrane surrounding lobules
  • clear cells centrally
  • can have scattered mitoses

DDx: clear cell IEC, clear cell SCC, clear cell acanthoma, sebaceous differentiation

150
Q

Inverted follicular keratoma

A

Endophytic , somewhat bulbous, lobular proliferation with squamous eddies
- keratinocyte proliferation seems to surround one or several follicular canals opening onto the surface

151
Q

Tumour of follicular infundibulum

A

Fenestrated and plate like structures

- pale pink cells

152
Q

Melanoma in situ

- superficial spreading

A

Symmetry/poor peripheral circumscription (but cannot comment on this on a partial biopsy specimen)/pagetoid/
Nested though Scatter of single cells throughout all levels of epidermis
Mitoses
Variable stromal reaction
Fibrosis within the dermis
Scatter of cells above basal layer

153
Q

Angiofibroma /fibrous papule of the nose

A

Concentric fibrosis around follicle
Angioma OPD stroma
Fibroblasts - can be multinucleated

154
Q

Superficial multifocal BCC

A

need to Comment on regression or evidence of tumour beyond scar

155
Q

IEC

A

Comment on solar elastosis, whether has an underlying epidermal lesion eg. Actinic keratosis
- look for dermal invasion
-

156
Q

Hydrocystoma

A
  • apocrine snouting

- Unilocular

157
Q

Blue naevus

- common sclerotic

A

Spindled dendritic melanocytes in dermis
Melanophages - histiocytes containing excess melanin pigment
Thickened collagen associated with lesion

158
Q

Neurofibroma

A

Spindle cell proliferation in dermis with wavy nuclei
Loose stroma with fibrillary architecture
Mast cells
No cytological atypia
Neurofibrosarcoma only really seen in context of neurofibromatosis

159
Q

Porphyria cutanea tarda

A

Caterpillar bodies - PAS positive
Dermal festooning
Paucicellular subepidermal blister

160
Q

Granuloma annulare

A

Closed off granulomas with necrobiosis
- Mucin, presence of eosinophils , less likely plasma cells
- perivascular lymphocytes
Usually upper portion of dermis (upper 1/3)
- areas of dermal dermis also present
- multinucleated giant cells

161
Q

Proliferating trichilemmal cyst

A

Abrupt keratinisation
—> transition to keratin
- can have cytological atypia
Akermann considered this a form of SCC

162
Q

Lichen sclerosus /balanitis xerotica obliteraans

A

Homogenisation of collagen in papillary dermis
Can have eosinophils
Can see smooth muscle and nerves in specimen of this area

163
Q

Mucocoele

A

Myxoid stroma
Pseudo cystic structure containing mucin
Glandular structures on lip

164
Q

Warty dyskeratoma

A

;Cup shaped invagination with acantholysis
- acantholytic dyskeratotis at the base and sides of a cup like epidermal invagination
Flattened parakeratosis = grains
Shrunken nuclear bodies with perinuclear halo

165
Q

Eccrine poroma

A

Monomorphous cell population
individual cells trying to form a duct
Connecting to epidermis
Raining down(classic)

166
Q

MF stains

A

CD2 - rarely lost
CD5 , 2 — both reliable T cell markers
CD4 , 8 — for clonality
CD30 — exclude LyP, ALCL

167
Q

Deep penetrating naevus

A

B-catenin positive

Extend down adnexal structures

168
Q

Clonal naevus

A

Small discrete nests of large pigmented epithelioid melanocytes

169
Q

DARIER VS. GROVER DISEASE

A

Both have acantholytic dyskeratosis
DARIER = more serum crust , more inflammation
GROVER = less serum crust, less inflammation

170
Q

PLEVA

A

Parakeratosis, lymphocytic vasculitis, erythrocytes extravasation, Vacuolar damage, apoptotic keratinocytes

171
Q

Dermal oedema seen in?

A 
Sweet syndrome
Id reaction
Urticaria
PMLE
Arthropod bite
Phytodermatitis
Perivascular oedema in perniosis
172
Q

Acral fibrokeratoma

A

Thick collagen bundles surrounded by bloods vessels, oriented perpendicular to the epidermis
DDx: ungal fibroma, supernumerary digit

173
Q

Desmoplastic melanoma

A

pauciceullar atypical Spindled cell proliferation - atypical, spindled, malignant melanocytes
- separated by fibrocollagenous stroma within the dermis or SC fat
- often overlying melanoma in-situ, typically of LM type
Areas that look like nerve
Lymphocytic aggregates
Do not stain positive for HMB-45 or Melan-A,
Can stain + for PRAME IHC stain

174
Q

Kaposi sarcoma

A

Haemosiderin and plasma cells at edges
Can have Polypoid appearance
Slit like spaces

175
Q

Angiosarcoma stains

A

ERG

C-MYC

176
Q

ALOPECIA AREATA

A

Terminal to vellus hair ratio 1:1
Prominent sebaceous glands
Fibrous streamers and miniaturisation can be seen
Swarm of bees lymphocytic inflammation
Can see pigmented casts
Large numbers of catagen and telogen hairs

177
Q

Granular parakeratosis

A

Retained keratohyalin granules

Can have epidermal necrosis and exocytosis of neutrophils

178
Q

Idiopathic scrotal calcinosis

A

Amorphous basophilic granular material

Giant cell granulomatous reaction at edges

179
Q

Dermato fibrosarcoma protuberans

A

Storiform configuration of spindled cells
Depth of involvement with honey combing
Fairly monomorphous cytology although invasive
- CD34
- Factor VIII

180
Q

Interface obscuring lichenoid reaction pattern

A 
EM
PLEVA
Fixed drug eruption
SJS / TEN
LE
181
Q

What can shadow keratinisation/cells be found in:

A

Pilomatricoma
Pilomatricarcinoma
BCC
Follicular adnexal neoplasms

182
Q

Sarcoidal granulomas can be seen in:

A 
FIGS RC
Sarcoidosis
Infections 
Foreign body granulomatous reaction pattern
Granuloma annulare
Rosacea 
Cutaneous Crohn’s disease
183
Q

Endophytic squamous proliferation - as a term rather than pseudoepitheliomatous hyperplasia

A

Favour reactive aetiology

184
Q

Sporothrix

A

—> can resemble asteroid body

185
Q

Suppurative granuloma

A
  • Contains abundant neutrophils

- subtle granulomas

186
Q

Gout

A

Fibrillar/Shieves of wheat appearance
Can ask to process in alcohol so crystals do not dissolve
Gout vs. pseudogout —> basophilic look to pseudogout as more calcified, gout with more pointy ends (soft sign)

187
Q

Perifollicular granulomatous reaction pattern

A
  • ruptured folliculitis
    —> can see flakes of keratin
    —> can see some necrosis though slightly unusual in folliculitis (see this in acne necrotica)
  • annular elastolytic giant cell granuloma
188
Q

Chalazion

A

Prominent plasma cells

Granulomatous reaction pattern

189
Q

Intravascular papillary endothelial hyperplasia / Masson’s tumour

A

Reactive proliferation of endothelial cells with papillary formations related to a thrombus
- can be mistaken for angiosarcoma

190
Q

Pityriasis rosea

A

Mild spongiosis and focal parakeratotic mounds
Superficial perivascular lymphocytic infiltrate with extravasated RBC, sometimes admixed eos
- DDx: EAC

191
Q

Keratoacanthoma

A 
Crateriform architecture with glassy eosinophilic atypia, 
Neutrophilic microabscesses, 
eosinophils and elastic trapping
- acantholysis never present
PNI can be present 
Lymphovascular invasion unlikely
SCC can be present in the base of KA
192
Q

Angiokeratoma

A

Acanthotic epidermis with hyperkeratosis

Intermixed dilated vessels surrounded by epidermis giving appearance of intraepidermal vessels

193
Q

Tumour of follicular infundibulum

A

Superficial distinct plate-like epithelial proliferation
MULTIPLE connections to epidermis - slender epidermal connections with basaloid or pale cells
Less hyperkeratosis than SebK

194
Q

Lichenoid keratosis

A

Lichenoid infiltrate composed primarily of lymphocytes with scattered histiocytes

  • eosinophils and plasma cells are sometimes present
  • see basal vacuolation, colloid bodies and melanin incontinence
195
Q

Epidermolytic acanthoma

A

FOUR COMPONENTS IN THIS HISTOLOGIC PATTERN:
1 - clear spaces of varying size surrounding nuclei in the stratum spinosum and stratum granulosum . Large cytoplasmic vacuolation of cells above basal layer with indistinct cell borders
2 - indistinct cellular boundaries consisting of reticulated, lightly staining material
3 - a markedly thickened granular zone containing an incr number of small and large, irregularly shaped, basophilic keratohyalin-like bodies
4 - compact hyperkeratosis

The basal layer is normal. Epidermolytic acanthomas generally demonstrate more papillomatosis than seen in other conditions with EHK.

196
Q

Angioleiomyoma

A

Well circumscribed, subcutaneous or dep dermal nodule. Large interfacing bundles of plump spindle cells with ample eosinophilic cytoplasm, cigar-shaped nuclei and paranuclear vacuoles arranged around slit like
Calcification very uncommon - can happen on acral sites

197
Q

Dermatofibrosarcoma protuberans

A
  • Dermal and SC proliferation of spindle cells in distinct storieform pattern; spindle cells are uniform with minimal atypia.
  • Involvement of subcutis imports a layered and honeycomb pattern.
  • No epidermal induction
  • Not necessarily extending to fat
  • CD34 stain positive
  • factor XIIa negative (unlike dermatofibroma)
198
Q

Morphoea

A

Dermal sclerosis with thick closely packed hyalinised collagen bundles. Loss of periadnexal fat, atrophy of adnexal structures, especially pilosebaceous units. Blood vessels appear narrowed with thickened walls. Sparse lymphoplasmacytic infiltrate.

199
Q

Chondroid syringoma

A

Benign tumour of sweat glands with a mucoid stroma showing cartilaginous metaplasia
- chondromyxoid stroma
Can be apocrine or eccrine

200
Q

Clonal naevus

A

Conventional compound naevus and naevus with large epithelioid melanocytes
- similar to deep penetrating naevus which has mutation in beta-catenin gene (but clonal naevus does not have mutation)

201
Q

Lichen striatus

A 
Focal parakeratosis
Mild acanthosis, sometimes psoriasiform
Spongiosis
Dyskeratotic keratinocytes sometimes
Focal basal layer liquefaction sometimes
Perivascular or lichenoid lymphocytes , often around follicles and ESPECIALLY AROUND SWEAT DUCTS (syringocentricity)
202
Q

Microcystic adnexal carcinoma

A

Infiltrative , poorly circumscribed eccrine neoplasm with focal Pilar differentiation

  • stratified growth pattern with microcyst in upper portion and small nests and single cells at the base
  • SUPERFICIAL: more squamous
  • INTERMEDIATE: Strands and small nests
  • DEEP: Cystic
  • nests of squamoid cells with minimal cytological atypia and duct form
203
Q

Traumatic neuroma

A

Proliferation of small bundles of well delineated nerve fascicles in a fibrotic stroma

204
Q

Angiosarcoma

A

Proliferation of Vessels surrounded by Enlarged endothelial cells
Surrounded by inflammatory infiltrates
CD31, CD34

205
Q

Perniosis

A

Superficial and deep lymphocytic
Fluffy perivascular oedema
Eccrine (peri eccrine) inflammation

206
Q

Desmoplastic melanoma

A

Often little in situ component
Spindled cell proliferation
Lymphoid aggregates at the edges

207
Q

Acral compound naevus

A

Larger irregularly shaped pigmented junctional nests
Sometimes pagetoid spread
Predominance of nests over lentiginous pattern
A lack of confluent lentiginous component
Usually well circumscribed and asymmetrical
Usually not inflamed

208
Q

Inverted follicular keratoma

A

Endophytic proliferation of squamous epithelium and basaloid cells with finger like projections into the dermis. Squamous eddies characteristically present, particularly at the base. Mild lymphohistiocytic infiltrate in dermis

209
Q

Dilated pore of winer

A

Keratin plugged dilated follicular infundibulum with small radiating epithelial projections

210
Q

Dilated pore of winer

A

Keratin plugged dilated follicular infundibulum with small radiating epithelial projections

211
Q

Granular cell tumours

A 
Proliferation of large round to polygonal cells with granular eosinphilic cytoplasm in sheets
Necrosis
Pleomorphism
Mitoses
Perineural activity
No invasion
212
Q

Chronic radiation dermatitis

A

Hyperkeratosis with epidermal atrophy
Hyalinised stroma and oedema of papillary dermis
Hyalinised vessel walls and intimate hyperplasia
Large stellate radiation fibroblasts with atypical changes
Loss of adnexa

213
Q

Proliferating trichilemmal cyst

A

Multilobulated tumour composed of lobules of squamous epithelium showing abrupt trichilemmal keratinisation. Peripheral palisading and thickened BM ma be noted. Focal keratinisation with squamous edges.

214
Q

Merkel cell carcinoma stains

A

CK20, CK7
chromogranin A
Synaptophysin
CD31 -for extension to lymph node /lymphatic invasion

Negative:

  • s100,
  • Common leukocyte antigen
  • TTF1 (small cell lung ca less likely to form sheets and trabeculae)
215
Q

Chronic cutaneous lupus erythematosus

A
  • BM thickening
  • Epidermal atrophy
  • Follicular plugging
  • Mucin DEPOSITION
  • Superficial and deep lymphocytic inflammation, periappendageal and peri-eccrine
216
Q

Glomus tumour

A

Proliferation of rounded, homogeneous, hyperchromatic glomus cells surrounding vascular lumina
Positive smooth muscle active
Negative CD31, 34

217
Q

Calcinosis cutis

A

Deeply basophilic brittle deposits in the dermis
Occasionally surrounded by foreign body reaction
Positive for von kossa and alizarin red

218
Q

Trichoadenoma

A

Multiple small doughnut like proliferation of keratolysis composed of eosinophilic squamous cells with large central horn cysts

  • epidermal type keratinisation with granular layer
  • fibroblastic stroma
219
Q

Large cell acanthoma

A

Acanthotic epidermis with cells showing large nuclei, almost twice the size of normal keratinocytes.
Occasional verrucous pattern with papillomatosis or hyperkeratotic pattern may be seen.

220
Q

Stain for naevus vs. melanoma

A

P16 - positive in naevi

Negative in melanoma

221
Q

Hailey hailey disease

A

Extensive acantholysis usually at mid epidermis resembling dilapidated brick wall. Follicle sparing (unlike Darier)
Focal dyskeratosis (eosinphilic band surrounding nucleus)
Perivascular lymphocytes
DIF -

222
Q

Atypical fibroxanthoma

A
  • CD10, CD99

Can stain positive for SMA

223
Q

Epithelial marker

A

P40 positive

In SCC

Dermatopathology (1 decks)

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