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Path Flashcards

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Dermatology Board Prep flashcards
1
Q

Stains for Langerhans cell histiocytosis

A

S100, CD1a and Langerin CD207

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2
Q

Elastin stains

A

Verhoeff van Gieson

Weigarts

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3
Q

Acantholysis and dyskeratosis - differentials?

A 
Hailey hailey
Darier
Grovers
Warty dyskeratoma
Acanthokytic acanthoma
Familial dyskeratotic comedones
Acantholyitc Ak
Acantholytic SCC
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4
Q

Small blue cell tumours

A 
LEMONS
Lymphoma
Ewing sarcoma
Merkel cell cancer/melanoma
Oat cell cancer of the lung
Neuroblastoma
Small cell endocrine cancer
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5
Q

Spindle cell tumours

A 
SLAMDUNKB
SCC
Leiomyomas
Angiosarcomas
Melanoma/merkel cell cancer
DFSP
Undifferentiated pleomorphic sarcoma
Neurofibroma
Kaposi's Sarcoma
\+ BCC
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6
Q

Lymphatic stain

A

D240

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7
Q

Types of multinucleated giant cells

A

Langhans cells - circular
Touton - circular with foamy centre
Foreign body - macrophages all together

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8
Q

Grenz Zone

A 
Granuloma faciale
Lymphoma cutis
Pseudolymphoma
B cell lymphoma
Lepromatous leprosy
Acrodermatitis chronica atrophans
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9
Q

Cornoid lamella histology

A

Column of parakeratosis with dyskeratosis underneath

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10
Q

Spindle cell tumour differential and the stains that go with it

A

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)

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11
Q

Acanthosis definition

A

Thickening of the epidermis

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12
Q

Types of giant cells

A

Langhans - horseshoe shape
Foreign body - nuclei dispersed more evenly
Touton - foamy cytoplasm with circular nuclei around non-foamy core

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13
Q

Merkel cell stains

A

CK20, neuron-speciifc enolase, TTF1 negative

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14
Q

Merkel cell appearance

A

Large, oval violet-blue cells that appear smudgy

Normally seen at base of rete ridges

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15
Q

Histiocyte appearance

A

Large, vacuolated nucleus

Develop into macrophage (CD-68) or dendritic, Langerhans cell

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16
Q

Nerve stain

A

S100, Bodian

Negative for Bodian with neurofibroma

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17
Q

T cell stain

A

CD3

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18
Q

Mononuclear cell stain

A

CD6

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19
Q

B cell stain

A

CD20

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20
Q

NK cell stain

A

CD56

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21
Q

Macrophage stain

A

CD68, lysozyme

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22
Q

Mast cell stain

A

CD117

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23
Q

Dermal dendrocyte staine

A

Factor 13a

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24
Q

Indeterminate cell stain

A

S100, CD1a, but no Birbeck granules

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25
Q

Pit rosea histology

A

Undulating epidermis with focal parakeratosis and spongiosis - may resemble small Pautrier microabscess
Lymphocyte exocytosis
Perivascular infiltrate
Extravasasted RBCs

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26
Q

Alcian blue

A

Blue; common mucin stain

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27
Q

Congo red

A

Red; typical for staining amyloid fibres

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28
Q

Crystal violet

A

Violet; can stain glia and neurons

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29
Q

Fontana-Masson

A

Black/pink or red; stains melanin

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30
Q

Luna stain

A

Purple/black; can stain mast cells and elastin

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31
Q

Nissl stain

A

Blue; stains the rough endoplasmic reticulum in neurons

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32
Q

Period Acid Schiff

A

Red/magenta; used to stain glycogen, basement membranes, reticular fibres, cartilage, glycoproteins, glycolipids and mucins in tissues.

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33
Q

Red Oil 3 stain

A

Red; used to stain fat emboli

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34
Q

Reticulin stain

A

Blue/black; stains reticular fibres

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35
Q

Sudan black stain

A

Brown-black; stains myelin tissue

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36
Q

Toulodine blue

A

Blue; stains mast cell granules

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37
Q

Van Gieson stain

A

Red/blue/yellow; used to study blood vessels and skin, can stain collagen, nucleus, red blood cells, cytoplasm

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38
Q

What is immunohistochemistry

A

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.

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39
Q

BCL2 stain

A

Used to distinguish between basal cell carcinomas and trichoepitheliomas

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40
Q

CD3 stain

A

T-cell marker; strongly positive in mycosis fungoides

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41
Q

CD4 stain

A

Helper T-cell marker

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42
Q

CD8 stain

A

Suppressor T-cell marker

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43
Q

CD20 stain

A

B-cell marker

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44
Q

CD30 stain

A

Can be used in the diagnosis of Hodgkin lymphoma and anaplastic lymphomas. Large cells: Golgi apparatus and membranous staining

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45
Q

CD31 stain

A

Helps to identify endothelial tumour

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46
Q

CD34 stain

A

Distinguishes different endothelial tumours and is positive in dermatofibrosarcoma

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47
Q

CD56 stain

A

Used in the diagnosis of non-Hodgkin lymphomas, leukaemias and small cell carcinomas

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48
Q

CD117 stain

A

Marker for KIT receptor and positive in various tumours including mastocytosis

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49
Q

CDKN2A (p16)

A

Tumour suppressor marker positive in HPV-associated tumours, actinic keratoses and squamous cell carcinoma

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50
Q

CK stain

A

Cytokeratins can be used to help distinguish benign from malignant adnexal tumours

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51
Q

CK20 stain

A

Specific for Merkel cell carcinoma. Can help identify adenocarcinomas of the gastrointestinal and reproductive system as well as gastrointestinal epithelial tumours

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52
Q

Cytokeratin High molecular weight

A

Used to detect ductal carcinomas, squamous cell carcinomas and other epithelial neoplasms

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53
Q

Desmin stain

A

Muscle marker

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54
Q

EMA stain

A

Used to identify eccrine neoplasms, Paget disease and sebaceous carcinomas

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55
Q

Factor 13 stain

A

Can help clinicians distinguish between dermatofibrosarcoma and dermatofibroma

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56
Q

HMB45 stain

A

Used to detect melanocytes, especially in melanoma but negative in desmoplastic melanoma

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57
Q

Melan-a stain

A

Can help identify melanocytic naevus cells and melanomas

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58
Q

S100 stain

A

Used to mark tumours of the melanocytes, both naevi and melanoma

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59
Q

SMA stain

A

Smooth muscle antigen

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60
Q

SOX-10 stain

A

Nuclear marker for melanocytic tumours

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61
Q

I want to find mucin - what should I stain?

A

PAS (periodic acid Schiff) for neutral mucin
Alcian Blue for acid mucin
Mucicarmine

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62
Q

I want to find melanin - stain?

A

Fontana-Masson

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63
Q

I want to find iron - stain?

A

Perl’s Prussian Blue

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64
Q

I want to find calcium - stain?

A

Von Kossa

Alizarin red

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65
Q

I want to find fibrin - stain?

A

MSB (Martius Scarlet Blue)

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66
Q

I want to find elastic fibres - stain?

A

EVG (Elastic Van Geisen) for reticular dermis

Orcein for papillary dermis

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67
Q

I want to find fat - stain?

A

Oil Red-O (Fat is dissolved in tissue processing, frozen section required)

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68
Q

I want to find mast cells - stain?

A

Toluidine Blue

Giemsa

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69
Q

I want to show bacteria - stain?

A

Gram (gram-negative organisms are very difficult to demonstrate)
Ziehl-Neilson for most mycobacteria (ZN for AFB)
Wade-Fite for M. Leprae

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70
Q

I want to show fungi - stain?

A

PAS

Grocott / Gomori methenamine silver (GMS)

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71
Q

B cell markers

A

CD20 and CD79a

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72
Q

Most mature lymphocytes markers

A

Leukocyte common antigen

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73
Q

I want to find macrophages, stain?

A

CD68

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74
Q

Jigsaw puzzle like histo structure

A

Cylindroma
Thickened basement membrane material
Elongated duct like spaces
These are apocrine

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75
Q

Where do you find squamous eddies

A

HPV

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76
Q

Schwanomma histo

A
  • 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
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77
Q

Schwanomma ddx

A
  • 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
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78
Q

Angiosarcoma stains

A

CD31 and CD34

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79
Q

Scabies histology

A

Pig tail sign
Lymphocytes, histiocytes, eosinophils
Lymphoid aggregates

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80
Q

Tick bite histology - which cells more?

A

Neutrophils

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81
Q

Intra cytoplasmic inclusion bodies are seen in what

A

Melanocytes

Adipocytes

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82
Q

Mitotic stain

A

PHH3

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83
Q

What is histiocytic sweets associated with

A

More Haem malignancy

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84
Q

Mast cell stain

A

Leider- goes red

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85
Q

Bed bug Latin name

A

Cimex lectularis

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86
Q

Differentials for subcorneal pustules

A 
Candida, tinea
Pustular psoriasis
Subcorneal pustular dermatosis
IgA pemphigus/IgG pemphigus
Pyoderma vegetans
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87
Q

Types of tattoo reactions

A

Sarcoidal (granulomatous)
Hypersensitive
Infectious –> suppurative

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88
Q

Epithelioid granuloma differentials

A

TB/Leprosy

Sarcoidosis –> 25% of granulomas can be perineural

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89
Q

Investigations that you would do for someone with erythema induratum

A

CXR, Quant Gold, Tuberculin skin test?

Ziehl Neelson stain, Mycoplasma PCR

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90
Q

Types of histologic GA

A

Perforating
Interstitial
Necrobiotic
Sarcoidal

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91
Q

Epithelioid cell tumour ddx

A 
SCC
Melanoma
AFX - more spindly 
Histiocytes 
Lymphomas - CD34
Angiosarcoma
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92
Q

Syphilis stain

A

Warthin starry

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93
Q

How do you distinguish eccrine from apocrine

A

Apocrine stains CD15

Apocrine has snouting /decapitation

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94
Q

Cells with grooves in them

A

Langerhans

T lymphocytes

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95
Q

Pagetoid spread

A 
Paget’s disease
Melanoma
Bowen’s
Sebaceous carcinoma
Histocytosis
96
Q

Melanoma stains

A

S100, SOX10, Melan-A, HMB45, PRAIME - latter good for margin control, but is an evolving subject

97
Q

Granular cell tumour

A

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

98
Q

Test for coeliac in DH

A

Transglutaminase
IgA
Anti-endomyosin antibodies
Gliadin

99
Q

Neural stains

A

s100 and SOX 10

100
Q

Myocytes

A

Spindle cells

brightly eosinophilic cytoplasm, blunt-ended, cigar-shaped nuclei

101
Q

Iron stain

A

Pearl stain

102
Q

What condition is sclerotic fibroma associated with

A

Cowdens

103
Q

What colour does colloidal iron stain and what does it stain

A

Blue

Mucin

104
Q

Mast cell stain

A

Toluidine blue

Giemsa

105
Q

What antibody can you do to distinguish ulcerative colitis and Crohn’s disease?

A

anti-Saccharomyces cerevisiae antibodies

106
Q

BCC stain

A

BerEP4
MOC31

Can be positive in adnexal tumours

107
Q

Low molecular weight cytokeratins

A

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

108
Q

High molecular weight cytokeratins

A

CK 5/6
CK 34 beta E 12

Can be positive in BCC, always positive in SCC, and almost invariably positive in adnexal tumors

109
Q

SOX10 for adnexal neoplasms

A

Negative in BCC and SCC but can be positive in adnexal tumours and is a good way to differentiate

110
Q

GCDF15

A

Negative in BCC and SCC, can be positive in adnexal

111
Q

Pagets staining

A

CEA cytokeratin 20

Can use GCDF 15

112
Q

Schmorl stain

A

Reduces properties of melanin to stain granules blue green

Easier than Fontana Mason

113
Q

Urticarial dermatitis- how is it different to urticaria

A

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

114
Q

What day should you do hormonal testing of the menstrual cycle

A

Day 5-7

115
Q

Granular cell tumour stains

A

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)

116
Q

Perineuroma stains

A

EMA
Claudin 1
Type IV collagen
Laminin

117
Q

Differentiation of malignant peripheral nerve sheath tumour from soft tissue sarcomas

A

Lacks H3K27me3- trimethylation of lysine 27 on his tone H3 which repress transcription
In about 80% of cases it lacks it

118
Q

Virus associated with Merkel cell carcinoma

A

Polyomavirus in 80%

119
Q

Merkel cell carcinoma stains

A

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

120
Q

Path for infantile haemangioma- stains

A 
GLUT1
Lewis Y antigen
Meridian
Fcgamma RIO
Wilms tumour protein
121
Q

What is satellite necrosis

A

Lots of lymphocytes around a single cell

122
Q

Alopecia areata path

A

Increased telogen count
Swarm of bees
Eos
Pigment casts

123
Q

Mycobacterium stain

A

Wade Fite
Ziel Nielson
Gram
Silver

124
Q

Dendritic stain

A

Factor 13a

125
Q

Types of granulomas

A 
Necrobiotic 
Sarcoidal 
Tuberculoid 
Foreign body
Suppurative
126
Q

Difference between sebaceous hyperplasia and adenoma

A

Hyperplasia not connected to epidermis

Adenoma is

127
Q

Which part of the hair follicle has a granular layer

A

Infundibular

128
Q

Spirochete stain sensitivity

A

60-90%, but not helpful if it’s alopecia

129
Q

Difference between GA and IGD

A

GA has collagen trapping and mucin

130
Q

If sebaceous adenoma is positive for all MTS stains, what is risk of MTS

A

5%

131
Q

Stains for liposarcoma

A

MDM2, CDK4, adipophilin, p16

CD10 in ~20%

132
Q

Stains for leiomyoma

A

SMA and desmin

Then can do HLRCC: fumarate hydratase to look for Reed syndrome

133
Q

Stains for leiomyosarcoma

A

actin, dermin, h-caldesmon, CD10

usually negative but can be positive: cytokeratin, S100 -

134
Q

stain to differentiate apocrine and eccrine

A

CD15 positive in apocrine not eccrine

135
Q

sebaceous glands - different names for different locations

A
  • Fordyce spots or granules: vermillion lip and oral mucosa
  • Meibomian glands: eyelids
  • Montgomery tubercles: areolae
  • Tyson glands: labia minora and prepuce
136
Q

Muir Torre stains

A

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

137
Q

Stains for amyloid

A

Crystal violet better

Congo red - shows apple green

138
Q

Muir Torre Syndrome stains

A

MSH 6
MSH 2
MLH1
PMS2

139
Q

Stain that is positive for AFX

A

CD10

140
Q

Masson trichome stain

A

Collagen: blue or green
Keratin and muscle: fiber
Bone: light red or pink

141
Q

Glomus cell stains

A

SMA and actin
Myosin may be positive
CD 34 and 31 negative

142
Q

Ddx for perivascular lymphocytic infiltrate

A 
7 Ls:
Lupus 
PMLE
Lymphoma 
Pseudolymphoma 
Jessners 
Lues 
Leprosy
143
Q

What are the features of HSV

A

Multinucleating
Marginación of chromatin
Molding of nuclei
Ballooning degeneration

144
Q

Ways to identify amyloid

A

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

145
Q

What is particular about ERPHB4 mutation

A

It’s an AVM mutation that’s more likely to have neuro involvement

146
Q

How to tell if urate/gout

A

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

147
Q

How is pseudogout different to gout

A

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

148
Q

Stain for leishmaniasis

A

Giemsa

?CD1a

149
Q

Stains to do for xanthomas

A

Oil red O - red
Scarlet red - red-brown
Schultz- cholesterol and cholesterol esters are blue green, positive in xanthomas except eruptive

And IHC CD68

150
Q

Gout tophi stains

A

Von Kossa
De Galantha more specific for urates
Negative birefringence with polarized light

151
Q

Gouty tophi histo

A

If formalin fixed: amorphous eosinophilic deposits in dermis and s/c tissue
Alcohol fixed: brown, needle shaped crystals

152
Q

Stains for glomovenous malformation and glomus

A

SMA
Vimentin
CD34

153
Q

Stains for neurofibroma

A

S100, C34, PGP9.5, factor 13a, myelin basic protein, neurofilaments
Bodian stain rarely performed - reveals axons

154
Q

Stains for schwanomma

A 
S100 
Vimentin 
Sox 10
MBP 
Neurofilament is negative
155
Q

Trichome stain

A

collagen is stained blue, nuclei are stained dark brown, muscle tissue is stained red, and cytoplasm is stained pink

156
Q

DFSP histopathology findings

A

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

157
Q

DF histology findings

A

Lobular
Acanthosis with hyperpigmented basal layer (dirty feet)
Collagen trapping
Variable mixture of spindle fibroblasts and histiocytes (can be xanthomatous)
F13a positive, CD34 negative

158
Q

IHC for CBCL

A

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

159
Q

Main CBCL histo features

A

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

160
Q

Eosinophilic spongiosis ddx

A

BAD
Bite/ Bullous (PV/PF, BP/PG,MMP, EBA)
ACD /AD
Drug eruption

Other: Well’s, MF, PEP, IP, Erythema toxicum Neonatorum

161
Q

Dermal eosinophilia ddx

A

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)

162
Q

Ddx for pale cells in epidermis

A

Sharp migration of pale cells:

Syphilis
Hartnup
Acrodermatitis enteropathica
Radiodermatitis
Pellagra, psoriasis
Necrolytic migratory erythema
Pagets
Clear cell acanthoma, papulosis, SCC
163
Q

Ddx of clear cell dermal tumours

A 
Sebaceous adenoma/carcinoma
Trichilemmoma/cyst
Pilomatricoma
Clear cell acanthoma/BCC/scc/hidradenoma/syringoma
Pagets
164
Q

Main ddx for foam cells

A 
Histiocytoses: JXG, NXG, LCH
Xanthomas
Sebaceous tumours
AFX
Leprosy
165
Q

Perniosis histo features

A 
Minimal epidermal change
Peri-v lymphocytic, can get lymphocytic vasculitis - sup and deep
Dermal oedema
RCC extravasation
Very dermal
166
Q

EM histo features

A 
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
167
Q

How is FDE different to EM

A

Melanophages
More neuts and eos
Lymphocyte exocytosis
May have papillary dermal fibrosis

168
Q

Granular parakeratosis histology

A

Thickened parakeratosis with retention of keratohyaline granules
Thickened eosinophilic stratum corneum

169
Q

Difference between photoallergic and phototoxic

A

Photoallergic is more eosinophilic

Phototoxic is more neutrophilic

170
Q

How are the physical urticarias different to normal urticaria

A

Have more neutrophils

171
Q

Stains to do for suppurative granuloma and infections

A

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

172
Q

Rheumatoid nodule histology and stains

A

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

173
Q

Actinic granuloma histology

A 
Solar elastosis
Elastophagocytosis
Diffuse granulomatous infiltrate
Reduction in elastin (van Gieson - stains elastin black)
No mucin
No necrobiosis
174
Q

Koilocyte

A

Raisin like nuclei with halo

175
Q

Two main strains of HPV that cause cutaneous warts

A

6 and 11

176
Q

HSV and VZV findings on histology

A

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

177
Q

Suggestions of fungal infection on histo

A 
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
178
Q

Cryptococcus stains

A

Central: PAS, methenamine silver, Fontana Masson
Capsule: alcian blue, mucinarme, Indian ink

179
Q

Leishmaniasis stain

A

Giemsa

180
Q

Donavonosis stains

A

Warthin starry
Leishman
Giemsa

Looking for parasitzed macrophages (Donovan bodies)

181
Q

Touton giant cell ddx

A

JXG
NXG
Dermatofibroma

Sometimes xanthomas

182
Q

JXG stains

A

CD68 +ve, Factor 13+ve
CD1a and Langerin –ve
10% other cells in lesion S100 +ve

183
Q

LCH histology

A

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

184
Q

Xanthoma histology

A

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

185
Q

Amyloidosis stains and colours

A

Crystal violet -> metachromatic
Congo red –> apple green birefringence
Pagoda red –> specific to amyloid, will be negative for colloid milium
Thoflavin T –> green-yellow

186
Q

Colloid milium stain

A

Van Gieson stains black

187
Q

Gout histology

A

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

188
Q

Stains to do in hypertrophic scar

A

Van Gieson - loss of elastin

189
Q

Difference between keloid and hypertrophic

A

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

190
Q

PXE histology

A 
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
191
Q

KHE genetic mutation

A

GNA14

192
Q

Stains for KHE

A

CD31, CD34, podoplanin (lymphatic endothelial), LYVE-1, VEGFR-3, Prox1, D240 ? latter from NSS

193
Q

Ix to do for KHE

A

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

194
Q

AFX stains

A

CD10 and CD99

195
Q

Proliferation marker

A

Ki67

196
Q

Cytotoxic T cell markers

A

Perforin
Granzyme
TIA-1

197
Q

Marker of systemic lymphoma

A

ALK-1

198
Q

Bowens disease main path features

A 
Parakeratosis/orthokeratosis
Loss of granular layer
Full thickness atypia
Eyeliner sign
\+/- clear cell change, +/- acantholysis
Loss of maturation
199
Q

Mucocele stains

A

Sialomucin is positive for PAS and mucopolysaccharide

And then Alcian blue or colloidal iron

200
Q

Digital mucous cyst histopathology

A

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

201
Q

Sebaceous carcinoma histology features

A 
Pagetoid spread
Clear cells - sebocytes
Mod-severe atypia
Stains: Oil Red O, Sudan Black
IHC: EMA, adipophilin
Do other pagetoid stains
202
Q

Ddx for syringoma

A

Microcystic adnexal carcinoma
Desmoplastic trichoepithelioma
Sclerosing BCC

203
Q

Syringoma histo and associations

A

‘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

204
Q

Poroma histology findings

A

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

205
Q

Cylindroma histology and association

A

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

206
Q

Eccrine spiradenoma histology and association

A 
'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
207
Q

Syringocystadenoma papilliferum histology

A 
Invaginations
Plasma cells
Papillomatous, papillary projections
Tumour open to surface of skin
Apocrine decapitation
Check for associated sebaceous naevus
208
Q

Hidradenoma papilliferum histology

A

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

209
Q

Hidradenoma histology

A

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

210
Q

Microcystic adnexal carcinoma histology and ddx

A 
Horn cysts
Squamous and basaloid epithelium
Fibrous stroma
PNI is common
Bottom heavy
Stain: CEA, EMA, keratin

Ddx:
Syringoma
Desmoplastic trichoepithelioma
Morphoeaform BCC

211
Q

What do melanocytes look like

A

Halo inside

212
Q

types of naevus cells

A

A: superficial dermis/DEJ - epithelioid
B: mid dermis, lymphocyte like
C: deeper - spindle

213
Q

Deep penetrating naevus histo

A

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

214
Q

CMN histo

A 
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
215
Q

Blue naevus histo

A 
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

216
Q

Spitz naevus histology

A

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

217
Q

Dysplastic naevus histology

A

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

218
Q

Types of melanoma and their findings

A

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

219
Q

Melanoma findings

A

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

220
Q

Breslow thickness

A

From top of Granular layer (or ulcer base) to deepest point of invasion  most important prognostic indicator

221
Q

Clark levels

A 
if epidermal (Level 1 or insitu) 
if papillary dermis (2), 
ablating interface papillary-Reticualr dermis (3)
deeper then (level 4), 
SC (level5)
222
Q

Stains for melanoma

A
  • MAIN: Melan-A (cytoplasmic), SOX-10 (NUCLEAR, red chromogen)
  • OTHERS: HMB-45, Ki-67 & P 16 lost
223
Q

Stains for LyP

A

CD30 +, CD4 +, TIA-1 +
Exclude nodal/systemic ALCL (ALK-1 +ve)
Differentiate from ALCL (MUM-1 & TRAF-1 +ve)

224
Q

Stains for primary follicular cbcl

A

CD20+
BCL-6 +, CD10 + (confined to the centre)
BCL2 –
Lamda or kappa light chain staining

225
Q

Stains for primary cutaneous marginal zone lymphoma

A 
CD20, CD79a  +ve
bcl-2 +ve
bcl-6 & Cd 10 –ve
Monoclonal Kappa or lambda 
(negative staining for CD5, CD10, CD23)
226
Q

Features of pseudolymphoma on histo

A 
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
227
Q

Glomuvenous stains

A

SMA
CD34
Vimentin

** not encapsulated

228
Q

Stains for Kaposis

A 
CD34
CD31
HHV8
ERG
D240
Perls
VEGFR-3, podoplanin, LYVE-1
229
Q

Neurofibroma features and stains

A 
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

230
Q

Schwanomma main features

A 
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

231
Q

Granular cell tumour main features

A

Polyhedral cells, granular
Eosinophilic granules: pustulo ovoid pustules of Milian

Stains: S100, PGP9.5, Myelin basic protein, CD68

232
Q

Merkel cell carcinoma main features

A

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

233
Q

Angiofibroma histo features

A

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

234
Q

Dermatofibroma histo features

A

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

235
Q

DFSP features

A

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

236
Q

AFX features

A

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

237
Q

Angioleiomyoma features

A

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

Derm (57 decks)

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