Path Flashcards
Stains for Langerhans cell histiocytosis
S100, CD1a and Langerin CD207
Elastin stains
Verhoeff van Gieson
Weigarts
Acantholysis and dyskeratosis - differentials?
Hailey hailey Darier Grovers Warty dyskeratoma Acanthokytic acanthoma Familial dyskeratotic comedones Acantholyitc Ak Acantholytic SCC
Small blue cell tumours
LEMONS Lymphoma Ewing sarcoma Merkel cell cancer/melanoma Oat cell cancer of the lung Neuroblastoma Small cell endocrine cancer
Spindle cell tumours
SLAMDUNKB SCC Leiomyomas Angiosarcomas Melanoma/merkel cell cancer DFSP Undifferentiated pleomorphic sarcoma Neurofibroma Kaposi's Sarcoma \+ BCC
Lymphatic stain
D240
Types of multinucleated giant cells
Langhans cells - circular
Touton - circular with foamy centre
Foreign body - macrophages all together
Grenz Zone
Granuloma faciale Lymphoma cutis Pseudolymphoma B cell lymphoma Lepromatous leprosy Acrodermatitis chronica atrophans
Cornoid lamella histology
Column of parakeratosis with dyskeratosis underneath
Spindle cell tumour differential and the stains that go with it
SLAMDUNK
SCC - CK903 and HMW keratin
Leiomyosarcoma - Desmin and SMA
Angiosarcoma - CD31 and CD34
Melanoma - S100 and MART-1
DFSP - CD34, negative for factor 13a and stromelysin
Undifferentiated pleomorphic sarcoma and AFX - CD68, CD10 and procollagen
Nodular fasciitis - HSP47, actin
Kaposi’s sarcoma - CD31, CD34, HHV-8 (Lana)
Acanthosis definition
Thickening of the epidermis
Types of giant cells
Langhans - horseshoe shape
Foreign body - nuclei dispersed more evenly
Touton - foamy cytoplasm with circular nuclei around non-foamy core
Merkel cell stains
CK20, neuron-speciifc enolase, TTF1 negative
Merkel cell appearance
Large, oval violet-blue cells that appear smudgy
Normally seen at base of rete ridges
Histiocyte appearance
Large, vacuolated nucleus
Develop into macrophage (CD-68) or dendritic, Langerhans cell
Nerve stain
S100, Bodian
Negative for Bodian with neurofibroma
T cell stain
CD3
Mononuclear cell stain
CD6
B cell stain
CD20
NK cell stain
CD56
Macrophage stain
CD68, lysozyme
Mast cell stain
CD117
Dermal dendrocyte staine
Factor 13a
Indeterminate cell stain
S100, CD1a, but no Birbeck granules
Pit rosea histology
Undulating epidermis with focal parakeratosis and spongiosis - may resemble small Pautrier microabscess
Lymphocyte exocytosis
Perivascular infiltrate
Extravasasted RBCs
Alcian blue
Blue; common mucin stain
Congo red
Red; typical for staining amyloid fibres
Crystal violet
Violet; can stain glia and neurons
Fontana-Masson
Black/pink or red; stains melanin
Luna stain
Purple/black; can stain mast cells and elastin
Nissl stain
Blue; stains the rough endoplasmic reticulum in neurons
Period Acid Schiff
Red/magenta; used to stain glycogen, basement membranes, reticular fibres, cartilage, glycoproteins, glycolipids and mucins in tissues.
Red Oil 3 stain
Red; used to stain fat emboli
Reticulin stain
Blue/black; stains reticular fibres
Sudan black stain
Brown-black; stains myelin tissue
Toulodine blue
Blue; stains mast cell granules
Van Gieson stain
Red/blue/yellow; used to study blood vessels and skin, can stain collagen, nucleus, red blood cells, cytoplasm
What is immunohistochemistry
HC uses primary antibodies to label a protein, then uses a secondary antibody which is bound to the primary one. In immunoperoxidase staining, an antibody is joined to an enzyme, peroxidase, that catalyses a reaction in which the protein is specifically stained brown. IHC can also involve fluorescently labelled antibody so that when viewed under a light microscope a certain pattern will be observed from the emitted fluorescence.
BCL2 stain
Used to distinguish between basal cell carcinomas and trichoepitheliomas
CD3 stain
T-cell marker; strongly positive in mycosis fungoides
CD4 stain
Helper T-cell marker
CD8 stain
Suppressor T-cell marker
CD20 stain
B-cell marker
CD30 stain
Can be used in the diagnosis of Hodgkin lymphoma and anaplastic lymphomas. Large cells: Golgi apparatus and membranous staining
CD31 stain
Helps to identify endothelial tumour
CD34 stain
Distinguishes different endothelial tumours and is positive in dermatofibrosarcoma
CD56 stain
Used in the diagnosis of non-Hodgkin lymphomas, leukaemias and small cell carcinomas
CD117 stain
Marker for KIT receptor and positive in various tumours including mastocytosis
CDKN2A (p16)
Tumour suppressor marker positive in HPV-associated tumours, actinic keratoses and squamous cell carcinoma
CK stain
Cytokeratins can be used to help distinguish benign from malignant adnexal tumours
CK20 stain
Specific for Merkel cell carcinoma. Can help identify adenocarcinomas of the gastrointestinal and reproductive system as well as gastrointestinal epithelial tumours
Cytokeratin High molecular weight
Used to detect ductal carcinomas, squamous cell carcinomas and other epithelial neoplasms
Desmin stain
Muscle marker
EMA stain
Used to identify eccrine neoplasms, Paget disease and sebaceous carcinomas
Factor 13 stain
Can help clinicians distinguish between dermatofibrosarcoma and dermatofibroma
HMB45 stain
Used to detect melanocytes, especially in melanoma but negative in desmoplastic melanoma
Melan-a stain
Can help identify melanocytic naevus cells and melanomas
S100 stain
Used to mark tumours of the melanocytes, both naevi and melanoma
SMA stain
Smooth muscle antigen
SOX-10 stain
Nuclear marker for melanocytic tumours
I want to find mucin - what should I stain?
PAS (periodic acid Schiff) for neutral mucin
Alcian Blue for acid mucin
Mucicarmine
I want to find melanin - stain?
Fontana-Masson
I want to find iron - stain?
Perl’s Prussian Blue
I want to find calcium - stain?
Von Kossa
Alizarin red
I want to find fibrin - stain?
MSB (Martius Scarlet Blue)
I want to find elastic fibres - stain?
EVG (Elastic Van Geisen) for reticular dermis
Orcein for papillary dermis
I want to find fat - stain?
Oil Red-O (Fat is dissolved in tissue processing, frozen section required)
I want to find mast cells - stain?
Toluidine Blue
Giemsa
I want to show bacteria - stain?
Gram (gram-negative organisms are very difficult to demonstrate)
Ziehl-Neilson for most mycobacteria (ZN for AFB)
Wade-Fite for M. Leprae
I want to show fungi - stain?
PAS
Grocott / Gomori methenamine silver (GMS)
B cell markers
CD20 and CD79a
Most mature lymphocytes markers
Leukocyte common antigen
I want to find macrophages, stain?
CD68
Jigsaw puzzle like histo structure
Cylindroma
Thickened basement membrane material
Elongated duct like spaces
These are apocrine
Where do you find squamous eddies
HPV
Schwanomma histo
- Encapsulated, well-circumscribed lesion beneath uninterrupted epidermis
- Antoni A: more cellular -> composed of haphazard arrangement of bland cells with spindled and oval nuclei
- Antoni B: lose, less cellular areas, with loose oedematous and mucinous stroma with fibrillar collagen. Vessels are prominent and often surrounded by dense sclerosis
- Verocay bodies: parallel columns of elongated nuclei either side of homogenous acellular material
- Positive for S100
Schwanomma ddx
- Neurofibroma: won’t be encapsulated
- Plexiform neurofibroma -> have nerves coursing through the mass
- Perineuroma: stains positive for EMA and S100
- DFSP: CD 34 positive, S100 negative and lacks Antoni A and Antoni B pattern of schwannoma
Angiosarcoma stains
CD31 and CD34
Scabies histology
Pig tail sign
Lymphocytes, histiocytes, eosinophils
Lymphoid aggregates
Tick bite histology - which cells more?
Neutrophils
Intra cytoplasmic inclusion bodies are seen in what
Melanocytes
Adipocytes
Mitotic stain
PHH3
What is histiocytic sweets associated with
More Haem malignancy
Mast cell stain
Leider- goes red
Bed bug Latin name
Cimex lectularis
Differentials for subcorneal pustules
Candida, tinea Pustular psoriasis Subcorneal pustular dermatosis IgA pemphigus/IgG pemphigus Pyoderma vegetans
Types of tattoo reactions
Sarcoidal (granulomatous)
Hypersensitive
Infectious –> suppurative
Epithelioid granuloma differentials
TB/Leprosy
Sarcoidosis –> 25% of granulomas can be perineural
Investigations that you would do for someone with erythema induratum
CXR, Quant Gold, Tuberculin skin test?
Ziehl Neelson stain, Mycoplasma PCR
Types of histologic GA
Perforating
Interstitial
Necrobiotic
Sarcoidal
Epithelioid cell tumour ddx
SCC Melanoma AFX - more spindly Histiocytes Lymphomas - CD34 Angiosarcoma
Syphilis stain
Warthin starry
How do you distinguish eccrine from apocrine
Apocrine stains CD15
Apocrine has snouting /decapitation
Cells with grooves in them
Langerhans
T lymphocytes
Pagetoid spread
Paget’s disease Melanoma Bowen’s Sebaceous carcinoma Histocytosis
Melanoma stains
S100, SOX10, Melan-A, HMB45, PRAIME - latter good for margin control, but is an evolving subject
Granular cell tumour
Nodule - blue cells: large cytoplasm with granules, S100 positive.
Rare. Occurs in the subcutaneous tissue in 30-40%, nearly 25% in the tongue.
1-3 cm, painless. 98% benign, malignant change rarely can occur
Test for coeliac in DH
Transglutaminase
IgA
Anti-endomyosin antibodies
Gliadin
Neural stains
s100 and SOX 10
Myocytes
Spindle cells
brightly eosinophilic cytoplasm, blunt-ended, cigar-shaped nuclei
Iron stain
Pearl stain
What condition is sclerotic fibroma associated with
Cowdens
What colour does colloidal iron stain and what does it stain
Blue
Mucin
Mast cell stain
Toluidine blue
Giemsa
What antibody can you do to distinguish ulcerative colitis and Crohn’s disease?
anti-Saccharomyces cerevisiae antibodies
BCC stain
BerEP4
MOC31
Can be positive in adnexal tumours
Low molecular weight cytokeratins
Cytokeratin 7 and 19 - positive in BCC, negative SCC, can be positive in adnexal
If the SCC has arisen from Bowen’s it can be cytokeratin 7 positive
Cytokeratin 20 is also a LMW
High molecular weight cytokeratins
CK 5/6
CK 34 beta E 12
Can be positive in BCC, always positive in SCC, and almost invariably positive in adnexal tumors
SOX10 for adnexal neoplasms
Negative in BCC and SCC but can be positive in adnexal tumours and is a good way to differentiate
GCDF15
Negative in BCC and SCC, can be positive in adnexal
Pagets staining
CEA cytokeratin 20
Can use GCDF 15
Schmorl stain
Reduces properties of melanin to stain granules blue green
Easier than Fontana Mason
Urticarial dermatitis- how is it different to urticaria
Has urticaria and eczema overlap
The more eos the more you need to think of BP
Biopsy: dermal dermatitis with mixed inflammatory cells in the dermis and minimal spongiosis in the epidermis
What day should you do hormonal testing of the menstrual cycle
Day 5-7
Granular cell tumour stains
S100
PGP9.5 - Neuron specific peptide
Neuron specific enolase
Nerve growth factor receptor
Can have histiocytic markers:
CD68, NKI/C3
Can have markers of melanocytic differentiation:
MITF
SOX10
True neural granular cell tumours have all of the above, non neural are the histiocytic markers (congenital granular cell tumour)
Perineuroma stains
EMA
Claudin 1
Type IV collagen
Laminin
Differentiation of malignant peripheral nerve sheath tumour from soft tissue sarcomas
Lacks H3K27me3- trimethylation of lysine 27 on his tone H3 which repress transcription
In about 80% of cases it lacks it
Virus associated with Merkel cell carcinoma
Polyomavirus in 80%
Merkel cell carcinoma stains
CK20, CK5/6, CK7 - corresponds to the ultrastructural distribution of paranuclear whorls of intermediate filaments
Positive staining for various neuro endocrine markers: chromogranin, synaptophysin, somatostatin, calcitonin, vasoactive intestinal peptide
Neuron specific enolase, occasionally neural filaments, CD56
S100 negative
Thyroid transcription factor 1 negative (helps differentiate from from cutaneous metastasis)
Could also do polyomavirus
P63 may indicate more aggressive behaviour
Path for infantile haemangioma- stains
GLUT1 Lewis Y antigen Meridian Fcgamma RIO Wilms tumour protein
What is satellite necrosis
Lots of lymphocytes around a single cell
Alopecia areata path
Increased telogen count
Swarm of bees
Eos
Pigment casts
Mycobacterium stain
Wade Fite
Ziel Nielson
Gram
Silver
Dendritic stain
Factor 13a
Types of granulomas
Necrobiotic Sarcoidal Tuberculoid Foreign body Suppurative
Difference between sebaceous hyperplasia and adenoma
Hyperplasia not connected to epidermis
Adenoma is
Which part of the hair follicle has a granular layer
Infundibular
Spirochete stain sensitivity
60-90%, but not helpful if it’s alopecia
Difference between GA and IGD
GA has collagen trapping and mucin
If sebaceous adenoma is positive for all MTS stains, what is risk of MTS
5%
Stains for liposarcoma
MDM2, CDK4, adipophilin, p16
CD10 in ~20%
Stains for leiomyoma
SMA and desmin
Then can do HLRCC: fumarate hydratase to look for Reed syndrome
Stains for leiomyosarcoma
actin, dermin, h-caldesmon, CD10
usually negative but can be positive: cytokeratin, S100 -
stain to differentiate apocrine and eccrine
CD15 positive in apocrine not eccrine
sebaceous glands - different names for different locations
- Fordyce spots or granules: vermillion lip and oral mucosa
- Meibomian glands: eyelids
- Montgomery tubercles: areolae
- Tyson glands: labia minora and prepuce
Muir Torre stains
MSH 2 MSH 6 MLH 1 PMS 2
If MSH 2 is negative - then more likely to have MTS
So looking for loss of these - they are micro stability arrays
Stains for amyloid
Crystal violet better
Congo red - shows apple green
Muir Torre Syndrome stains
MSH 6
MSH 2
MLH1
PMS2
Stain that is positive for AFX
CD10
Masson trichome stain
Collagen: blue or green
Keratin and muscle: fiber
Bone: light red or pink
Glomus cell stains
SMA and actin
Myosin may be positive
CD 34 and 31 negative
Ddx for perivascular lymphocytic infiltrate
7 Ls: Lupus PMLE Lymphoma Pseudolymphoma Jessners Lues Leprosy
What are the features of HSV
Multinucleating
Marginación of chromatin
Molding of nuclei
Ballooning degeneration
Ways to identify amyloid
Crystal violet metachromasia
Positive staining with alkaline Congo red
Apple green birefringence under polarised light after Congo red staining
Thioflavin T staining: brightly by UV fluorescence microscopy
Antibodies to amyloid P
Stain against specific precursors like keratin
What is particular about ERPHB4 mutation
It’s an AVM mutation that’s more likely to have neuro involvement
How to tell if urate/gout
20% silver nitrate - crystals appear bland and surrounding tissue yellow
De Galantha stain - crystals brown black (normal tissue yellow)
Polarized light: brightly refractile brown sheaths of fine needle-like crystals can be seen
How is pseudogout different to gout
CPPD crystals are shorter than urate, and rhomboidal in shape
Tophaceous pseudogout: rhomboid crystals as well as foci of calcification are seen within the dermis
Stain with non-aqueous alcoholic eosin stain –> CPPD crystals with positive birefringence, as opposed to negative birefringence in gout and tumoral calcinosis
Stain for leishmaniasis
Giemsa
?CD1a
Stains to do for xanthomas
Oil red O - red
Scarlet red - red-brown
Schultz- cholesterol and cholesterol esters are blue green, positive in xanthomas except eruptive
And IHC CD68
Gout tophi stains
Von Kossa
De Galantha more specific for urates
Negative birefringence with polarized light
Gouty tophi histo
If formalin fixed: amorphous eosinophilic deposits in dermis and s/c tissue
Alcohol fixed: brown, needle shaped crystals
Stains for glomovenous malformation and glomus
SMA
Vimentin
CD34
Stains for neurofibroma
S100, C34, PGP9.5, factor 13a, myelin basic protein, neurofilaments
Bodian stain rarely performed - reveals axons
Stains for schwanomma
S100 Vimentin Sox 10 MBP Neurofilament is negative
Trichome stain
collagen is stained blue, nuclei are stained dark brown, muscle tissue is stained red, and cytoplasm is stained pink
DFSP histopathology findings
Spindle cells in deep dermis and subcutaneous fat
Form herring bone or honeycomb or storiform pattern
Spindled or wavy nuclei
Pigmented variant: Bednar tumour
CD34 positive, Factor 13a negative, stromelysin 3 negative
DF histology findings
Lobular
Acanthosis with hyperpigmented basal layer (dirty feet)
Collagen trapping
Variable mixture of spindle fibroblasts and histiocytes (can be xanthomatous)
F13a positive, CD34 negative
IHC for CBCL
CD20, CD 79a
Follicular: Cd10 positive, BCL-2 negative
Leg type: BCL-2 positive (marginal zone also BCL-2 positive)
Exclude systemic: MUM-1, CD5, CD23
Main CBCL histo features
Grenz zone
Follicular: 25% follicular, 75% diffuse, has centrocytes and centroblasts. Positive CD10 (sometimes), CD20, 79a, negative BCL-2, MUM-1, CD5, CD23
Marginal zone: marginal zone cells (pale), plasma cells, eos, Dutcher bodies
Eosinophilic spongiosis ddx
BAD
Bite/ Bullous (PV/PF, BP/PG,MMP, EBA)
ACD /AD
Drug eruption
Other: Well’s, MF, PEP, IP, Erythema toxicum Neonatorum
Dermal eosinophilia ddx
Dermal eosinophilia ddx BAD - FUGUE (No vasculitis)
Bite/ BP (BP/PG,MMP, EBA)
ACD/AD
Drug eruption
Fungal inf (+Neut) Urticaria (+Neut & edema) GF (+Neut), Eos Granuloma (+ LCH) Unknown? Dermal HSR Eos folliculitis Eos Cellulitis (WELLS)
Ps: Angiolymphoid hyperplasia with eosinophilia (if +VESSELS & Plump endothelial cells)
Ddx for pale cells in epidermis
Sharp migration of pale cells:
Syphilis Hartnup Acrodermatitis enteropathica Radiodermatitis Pellagra, psoriasis Necrolytic migratory erythema Pagets Clear cell acanthoma, papulosis, SCC
Ddx of clear cell dermal tumours
Sebaceous adenoma/carcinoma Trichilemmoma/cyst Pilomatricoma Clear cell acanthoma/BCC/scc/hidradenoma/syringoma Pagets
Main ddx for foam cells
Histiocytoses: JXG, NXG, LCH Xanthomas Sebaceous tumours AFX Leprosy
Perniosis histo features
Minimal epidermal change Peri-v lymphocytic, can get lymphocytic vasculitis - sup and deep Dermal oedema RCC extravasation Very dermal
EM histo features
Basketweave stratum corneum (acute) Lichenoid/interface Civatte bodies Mild epidermal spongiosis Dermal oedema Lymphs and eos (latter can be sparse) DIF: non specific, granular deposits of IgM and C3 around BV and at DEJ
How is FDE different to EM
Melanophages
More neuts and eos
Lymphocyte exocytosis
May have papillary dermal fibrosis
Granular parakeratosis histology
Thickened parakeratosis with retention of keratohyaline granules
Thickened eosinophilic stratum corneum
Difference between photoallergic and phototoxic
Photoallergic is more eosinophilic
Phototoxic is more neutrophilic
How are the physical urticarias different to normal urticaria
Have more neutrophils
Stains to do for suppurative granuloma and infections
Gram (Brown–Brenn) Bacterial infections
Periodic acid Schiff (PAS) (Fungal cell walls Black/Mycotic infections)
Grocott (GMS) methenamine silver (Fungal cell walls Black/Mycotic infections)- Black
Ziehl–Neelsen Mycobacterial infections
Wade-Fite Mycobacterium TB/ leprae/ MOTT (mycobacteria other than tuberculosis)
Warthin–Starry? Spirochetes (Syphilis), Granuloma inguinale (Donovanosis) , Rhinoscleroma, Bacillary angiomatosis
Giemsa? leishmania
Rheumatoid nodule histology and stains
Large irregular granulomas with central necrobiosis (palisading macrophages)
Appear pink in nature
This is from fibrin –> stain positive for Martius Scarlet Blue
Will be negative for mucin
Actinic granuloma histology
Solar elastosis Elastophagocytosis Diffuse granulomatous infiltrate Reduction in elastin (van Gieson - stains elastin black) No mucin No necrobiosis
Koilocyte
Raisin like nuclei with halo
Two main strains of HPV that cause cutaneous warts
6 and 11
HSV and VZV findings on histology
Epidermal spongiosis
Intra-epidermal vesiculation
Pale keratinocytes
Acantholysis
Keratinocytes have viral changes: molding, margination, multinucleate, pale grey, enlarged
Intra-nuclear eosinophilic inclusions: Cowdry type A or Lipschutz bodies
Peri-v lymphs and neuts - sometimes vasculitis
Suggestions of fungal infection on histo
Sandwich sign: alternating ortho and parakeratosis with basketweave stratum corneum Neutrophils in the stratum corneum Septate hyphae Can be an invisible dermatosis Spongiosis, peri-follicular neutrophils
Cryptococcus stains
Central: PAS, methenamine silver, Fontana Masson
Capsule: alcian blue, mucinarme, Indian ink
Leishmaniasis stain
Giemsa
Donavonosis stains
Warthin starry
Leishman
Giemsa
Looking for parasitzed macrophages (Donovan bodies)
Touton giant cell ddx
JXG
NXG
Dermatofibroma
Sometimes xanthomas
JXG stains
CD68 +ve, Factor 13+ve
CD1a and Langerin –ve
10% other cells in lesion S100 +ve
LCH histology
Diffuse dermal infiltrate of
Large histocytes with with indented or RENIFORM (“coffee-bean” or Kidney shape) nucleus and abundant eos cytoplasm
Often mixed with various inflammatory cells lymph + Eos (esp if eosinophilic granuloma Eos +++)
epidermotropism also seen (which differs from mastocytosis)
EM = Birbeck granules (“tennis racquet”) within cells
Positive CD1a, S100, Langerin (CD207)
Negative CD68, factor XIIIa
Xanthoma histology
Foamy histiocytes (rarely touton giant cell)
older lesions have cholesterol clefts
neuts in young lesions, particularly eruptive
Stain positive for: Oil Red O (cholesterol goes red) , Scarlet Red (goes red), Schultz (goes blue-green)
CD68 positive
Amyloidosis stains and colours
Crystal violet -> metachromatic
Congo red –> apple green birefringence
Pagoda red –> specific to amyloid, will be negative for colloid milium
Thoflavin T –> green-yellow
Colloid milium stain
Van Gieson stains black
Gout histology
Granulomatous reaction with macrophages and foreign body giant cells
acellular bluish material in dermis; negative birefringence with polarized light (unlike pseudogout)
Formalin-fixed = amorphous, eosinophilic deposits in dermis and subcutaneous tissue (crystals dissolved)
Alcohol-fixed = brown, needle-shaped crystals (doubly refractile)
Positive staining with von Kossa, but de Galantha is more specific for urates
Stains to do in hypertrophic scar
Van Gieson - loss of elastin
Difference between keloid and hypertrophic
Keloid has more mucin, no epidermal involvement, decreased vascularity, no incr in fibroblasts
Hypertrophic: has vertically oriented capillaries, epidermal involvement, no incr in mucin, parallel oriented collagen and fibroblasts
PXE histology
Bx from (affected or normal skin): “Purple-squiggles” or “bramble-bush” disease Fragmented, short, basophilic, calcified elastic tissue fibers in mid-dermis (only elastic disorder you can see with only H & E stain) calcifications -> Calcium salts are deposited on the abnormal elastic fibers (do not confuse with calcinosis cutis) von Kossa method stains calcified elastic fibers black and VVG stains elastic fibers
KHE genetic mutation
GNA14
Stains for KHE
CD31, CD34, podoplanin (lymphatic endothelial), LYVE-1, VEGFR-3, Prox1, D240 ? latter from NSS
Ix to do for KHE
MRI (enhances on T2 hyperintense, ill-defined margin that crosses tissue planes), FBC, coagulation studies, platelets, fibrinogen degradation products, biopsy for histopath if safe to do so
AFX stains
CD10 and CD99
Proliferation marker
Ki67
Cytotoxic T cell markers
Perforin
Granzyme
TIA-1
Marker of systemic lymphoma
ALK-1
Bowens disease main path features
Parakeratosis/orthokeratosis Loss of granular layer Full thickness atypia Eyeliner sign \+/- clear cell change, +/- acantholysis Loss of maturation
Mucocele stains
Sialomucin is positive for PAS and mucopolysaccharide
And then Alcian blue or colloidal iron
Digital mucous cyst histopathology
Acral skin
well-circumscribed dermal accumulation of mucin + stellate fibroblasts
Pseudowall is made of dense fibrous tissue
Collarette of epidermal RR may clutch the mucin
Not considered a true cyst
Can have epidermal collarette trying to embrace mucin
Sebaceous carcinoma histology features
Pagetoid spread Clear cells - sebocytes Mod-severe atypia Stains: Oil Red O, Sudan Black IHC: EMA, adipophilin Do other pagetoid stains
Ddx for syringoma
Microcystic adnexal carcinoma
Desmoplastic trichoepithelioma
Sclerosing BCC
Syringoma histo and associations
‘Tadpole’ like structures
Proliferation of eccrine ducted structures
Horn cysts and milia may be present
Stroma fibrotic or sclerotic
Ducts are lined with 2 layers of flattened cuboidal epithelium, and ducts are CEA positive
Associations: Down Syndrome, Nicolau-Balus
Poroma histology findings
Infiltrate of poroid cells: small, monomorphous nucleus and scant eosinophilic cytoplasm
Sharp demarcation between epidermis and tumour
Poroid cells may be clear due to accumulation of glycogen - PAS positive
Dilated ducts with secretions
Stain: EMA and CK7 positive
Ducts are CEA positive
If deep and loose then call it a dermal duct tumour
Cylindroma histology and association
Jigsaw puzzle
Lobules have 2 cell types: peripheral darker small cells, and larger pale cells in the centre
Eosinophilic basement membrane
In the tumour there are hyalinized droplets - due to thickened basement membrane, PAS positive
Associated with Brooke-Spiegler
Eccrine spiradenoma histology and association
'Blue balls in dermis' Not encapsulated Three types of cells: 1. Large cuboidal with eosinophilic cytoplasm 2. Small basaloid with dense hyperchromatic 3. Lymphocytes Peripheral vascular channels prominent Ductal structures may be present CEA positive and PAS negative
Syringocystadenoma papilliferum histology
Invaginations Plasma cells Papillomatous, papillary projections Tumour open to surface of skin Apocrine decapitation Check for associated sebaceous naevus
Hidradenoma papilliferum histology
Circumscribed tumour
No connection to epidermis
Maze like granuldar spaces that are apocrine (decapitation)
Papillary folds
2 layers: myoepithelial and inner cuboidal
Often on vulva
Hidradenoma histology
Deep dermal nodular tumour
Can be poroid: poroid cells, ductal, keratinous cysts
Can be apocrine: multi-lobular, duct like, polyongal, clear, mucinous
Association: seb naevus and syringocystadenoma papilliferum
Microcystic adnexal carcinoma histology and ddx
Horn cysts Squamous and basaloid epithelium Fibrous stroma PNI is common Bottom heavy Stain: CEA, EMA, keratin
Ddx:
Syringoma
Desmoplastic trichoepithelioma
Morphoeaform BCC
What do melanocytes look like
Halo inside
types of naevus cells
A: superficial dermis/DEJ - epithelioid
B: mid dermis, lymphocyte like
C: deeper - spindle
Deep penetrating naevus histo
junctional nests are only small in most cases.
It may have a wedge shape on low power, with the apex of the wedge directed toward the deep dermis.
The lesion is composed of loosely arranged nests and fascicles of pigmented nevus cells, interspersed with melanophages.
Spindle cells are the predominant cell type, but varying numbers of epithelioid cells are also present. The nests extend into the deep reticular dermis and often into the subcutaneous fat
They surround hair follicles, sweat glands, and nerves. Pilar muscles are sometimes infiltrated
CMN histo
Usually in lower 2/3 of dermis Naevus cells Deep - peri-adnexal, peri-vascular, peri-follicular Single filing / 'indian filing' Seen in arrector pili mm
Blue naevus histo
Grenz zone Wedge shaped Spindle shaped melanocytes, and dendritic melanocytes Sclerosis - can confuse with DF Melanophages Lack maturation Pigment can be subtle
Stain: HMB45 - whole lesion positive
Subtype: cellular - more pale
Spitz naevus histology
Wedge shaped, symmetric
‘Raining down’
Kamino bodies in epidermis - eosinophilic globules (PAS positive)
Nests of melanocytes, whicha re spindled or epithelioid
Clefting/cleavage at junctional zone
Maturation preserved
Stains: S100, HMB45, Melan-A
Pigmented = Reed naevus
Dysplastic naevus histology
Nests of various sizes and shapes with bridging between nests
Lentiginous epidermal hyperplasia with nevus cells present in nests and as single cells along the junction
“shoulder phenomenon” (peripheral extension of junctional component beyond the dermal component
Random cytological cell atypia: occasional cells with enlarged hyperchromatic nuclei +/- prominent nucleoli. (The atypia is usually graded into low grade and severe)
fibroplasia of papillary dermis around junctional melanocytes
maturation of dermal melanocytes if dermal nests present
Some mitosis BUT NO DEEP mitosis (unlike melanoma)
Mild to moderate lymph in dermis
Types of melanoma and their findings
LMM:
Single (lentiginous melanocytic Hyperplasia) or nested atypical melanocytes, confined to basal layer & with little pagetoid spread
epidermal atrophy
Solar elastosis (However, not pre-request for dx)
The invasive component usually spindled atypical melanocytes
often MN melanocytes with prominent dendrites at basal layer (Starburst Giant cells)
SSM: Single or nested atypical melanocytes, at all levels within Epidermis, Extensive pagetoid spread (buckshot scatter)
Nodular: Dermal atypical melanocytes, often No intraEpid component
Acral Lentiginous MM: Acral skin+ Lentiginous elongation of RR with atypical melanocytes in basal layer, some buckshot scatter (pagetoid) not as marked as SSM
Melanoma findings
Asymmetry of lesion
Poor peripheral circumscription (ie single atypical melanocytes trail off at the edges beyond the last nest).
Epidermis atrophic hypertrophic or ulceration
Proliferation of both single and nested atypical melanocytes within the epidermis and extending into the dermis
Nests are:
Confluent, variable in size, shape & distribution
lack of maturation in depth (as they descend into the dermis)
Variability in melanin distribution
Single cells:
There is confluent lentiginous melanocytic proliferation
Pagetoid spread
Cytological atypia: variable (sometimes slight)
Nuclear Hyperchromatism, pleomorphism
Increased mitosis (per mm2), sometimes atypical or deep
Often lichenoid dermal lymphocytic infiltrate, less perivascular or sparse
+/- lymphatic, vascular or perineural invasion, fibrotic changes of regression or microsatellite deposits
Breslow thickness
From top of Granular layer (or ulcer base) to deepest point of invasion most important prognostic indicator
Clark levels
if epidermal (Level 1 or insitu) if papillary dermis (2), ablating interface papillary-Reticualr dermis (3) deeper then (level 4), SC (level5)
Stains for melanoma
- MAIN: Melan-A (cytoplasmic), SOX-10 (NUCLEAR, red chromogen)
- OTHERS: HMB-45, Ki-67 & P 16 lost
Stains for LyP
CD30 +, CD4 +, TIA-1 +
Exclude nodal/systemic ALCL (ALK-1 +ve)
Differentiate from ALCL (MUM-1 & TRAF-1 +ve)
Stains for primary follicular cbcl
CD20+
BCL-6 +, CD10 + (confined to the centre)
BCL2 –
Lamda or kappa light chain staining
Stains for primary cutaneous marginal zone lymphoma
CD20, CD79a +ve bcl-2 +ve bcl-6 & Cd 10 –ve Monoclonal Kappa or lambda (negative staining for CD5, CD10, CD23)
Features of pseudolymphoma on histo
Grenz zone Tingible body macrophage Eos and plasma cells Polarization: will see dark and light Stains for B and T cells Bcl-6 restricted to lymph follicles Mixed kappa and gamma
Glomuvenous stains
SMA
CD34
Vimentin
** not encapsulated
Stains for Kaposis
CD34 CD31 HHV8 ERG D240 Perls VEGFR-3, podoplanin, LYVE-1
Neurofibroma features and stains
Grenz zone Unencapsulated Spindle cells in dermis - wavy, cigar shaped Mast cells Pale, pink stroma
Stains: S100, SOX10, CD34, myelin basic protein
Bodian stain will show 1:1
Schwanomma main features
Encapsulated Verrocay bodies Alternating hypercellular (Antoni A) and hypocellular (Antoni B) Mucinous stroma Mast cells
Stains: S100 protein,vimentin,SOX 10,and myelin basic proteinin the tumor cells.
Neurofilament -ve
Granular cell tumour main features
Polyhedral cells, granular
Eosinophilic granules: pustulo ovoid pustules of Milian
Stains: S100, PGP9.5, Myelin basic protein, CD68
Merkel cell carcinoma main features
Sheets of blue cells in dermis and down to fat
Mitoses and necrosis
Tumour cells are small to medium-size with Scanty Cytoplasm + dense round nuclei+ Molding
- ‘salt and pepper’
Stains:
Positive for CK20, chromogranin, synaptophysin, CK7??
Negative for TTF-1 –> lung mets
Ber-EP4 - BCC
S100, melan-a - melanoma
CD45/leukocyte common antigen - lymphoma
Angiofibroma histo features
rounded elevations to raised pedunculated growths
The epidermis shows some flattening of rete ridges
The dermal component consists of a network of collagen fibers, often oriented perpendicular to the surface in the subepidermal zone and having an onion-skin arrangement around follicles and sometimes blood vessels
There is an increase in ‘fibroblastic’ cells, which are plump, spindle shaped, stellate, or even multinucleate.
There is often a sparse inflammatory infiltrate that includes mast cells.
The blood vessels are increased in number, and some are dilated with an irregular outline
Dermatofibroma histo features
Acanthotic epidermis with hyperpigmented basal layer (Dirty feet)
poorly demarcated
Sometimes there are aggregates of basaloid cells with follicular differentiation emanating from the epidermis (follicular and basaloid “induction”)
Variable admixture of
Spindle Fibroblast
Histiocytes (some of which may be xanthomatous or multinucleate- foam cells, giant cells)
Haemorrhage, haemosiderin and increased vessels
Hyalinized stroma/ peripheral “entrapped” collagen bundles
Cytologic features unremarkable spindle cells
Stains
Factor XIIIa +ve
CD34 -ve
DFSP features
Poorly circumscribed proliferation of monomorphic spindle cells in deep dermis
Storiform or cartwheel arrangement of cells
Cells spindled or wavy nuclei and little cytoplasm
Extends along fat septa- in a Honey-comb pattern
Mild atypia & Few mitoses
In < 5% Pigmented variant = Bednar tumour
Look for -Fibrosarcomatous degeneration in DFSP (dedifferentiation): foci with more atypia and mitoses, transformation to fibrosarcoma or malignant fibrous histiocytoma with risk of metastasis
Stains
+ve: CD34
-ve: S100 -ve (exclude spindle cell melanoma), Factor 13a -ve (exclude DF), CD31-ve, (exclude angiosarcoma), SMA -ve (exclude leiomyosarcoma
AFX features
well-circumscribed, non-encapsulated, highly cellular dermal tumour
composed of spindle cell, epithelioid cells or MNG & sometimes foamy cells
Tumour cells are Bizarre with prominent pleomorphism, hyperchromatism & many atypical mitosis -Multinucleated tumour giant cells (monster cells)
Background Solar elastosis
Doesn’t invade the subcutis- is so consider UPS
Focal proliferation of atypical epithelioid or spindled cells with pleomorphic nuclei and common mitoses
Stain:
+ve CD10/CD99
Do spindle cell panel-ve all other spindle cell stains -it’s a DX BY EXCLUSION
Angioleiomyoma features
well-circumscribed tumours cantered within the superficial subcutis.
composed of bland smooth muscle cells compactly arranged into bundles
whorls around thick-walled vascular channels
spindle cells: cigar like
Stains: desmin, actin
