Histopathology Flashcards
Atypical fibroxanthoma
Dermal spindle cell tumour
Stains: CD10, CD68
Deep= pleomorphic dermal sarcoma
Spindle cell tumours
- Spindle cell melanoma
- Spindle cell SCC
- AFX/PDS
- Other sarcomas:
E.g. Leimyosarcoma (fasicular appearance); dermatofibrosarcoma protuberans; angiosarcoma - If benign: dermatofibroma, neurofibroma (wavy appearance; mast cells), leiomyoma (cigar cells)
- Scar
Markers:
SCC: cytokeratin stains
Smooth muscle: SMA, desmin, caldesmon
Vascular: CD31, CD34, ERG
Granulomatous processes
- Granuloma annulare
- Rheumatoid nodule
- Necrobiosis lipoidica
- Foreign body reaction
- Infection
Stains for granulomatous histo (for infection)
- PAS (Periodic Acid Schiff stain) or GMS (Grocott’s methenamine silver)
- Ziehl Neelson or Wade Fite stain
- Gram stain
Stains for melanocytes
SOX 10 - negative in histiocytes
S100 - can also stain positive histiocytes/dendritic cells
Melan-A
PRAME
HMB-45
Stains for SCC
AE1/AE3 (PCK-pancytokeratin)
Cytokeratin MNF116
CK56
P40, P63
Keratin-filled cysts
Epidermoid cyst - keratin more laminated
Dermoid cyst
Trichilemmal (pilar) cyst (missing granular layer) - keratin more compact
Pilomatricoma
Cystic SCC
Skin adnexal tumours e.g. poroma (less cystic)
Steatocystoma - sebaceous lobules in cyst wall, wavy keratin, absent granular layer, contains sparse keratin and sebaceous material
Trichoepithelioma
Blue cell tumours
BCC
Melanoma
Merkel cell/neuroendocrine
Lymphoma
Metastasis
Basaloid SCC
Merkel Cell Stain
Perinuclear dotting staining AE1/AE3
CD56
Chromogranin
Synaptophysin
CK20 - perinuclear dottiing
Poliomavirus stain
Syringoma
Nests, cords, ductular structures (containing pink amorphous material), can be like tadpoles/comma shapes
Ddx: trichoepithelioma, BCC, microcystic adnexal carcinoma
Stains for DF vs DFSP
DF: 13A, CD10
DFSP: CD34
Blue naevus
Spindle cells
Dense pigment
Granular melanin
Well circumscribed
SCC in situ
No maturation of keratinocytes in epidermis (just as large on top as on bottom of epidermis)
Mitoses
Nuclear pleomorphism
Upper dermal lichenoid inflammation
Neurofibroma
Spindle cell tumour
Mast cells
S100 positive (patchy)
CD34 positive (swirling pattern)
SMA negative (just staining blood vessels)
Can be polypoid
Ddx:
Palisaded and encapsulated neuroma
Schwannoma
herpes inclusions
multinucleation
moulding
margination
Stains for BCC
BerEp4
Trichilemomma
Clear cells (follicular epithelial cells)
Well circumscribed, symmetrical
Associations: Cowdens (PTEN mutation, also a/w breast, thyroid, GI ca)
Eccrine spiradenoma
Lesions that are painful
Blend an egg
Blue rubber bleb
Leimyoma
Eccrine spiradenoma
Neuroma
Dermatofibroma
Angiolipoma
Neurilemomma
Endometriosis
Granular cell tumour
Glomus tumour
Schwannomas
Angiolipomas
Glomus tumours
Granular cell tumours
Tufted angiomas
Leiomyomas
Keratoacanthoma (wdSCC, keratoacanthoma type)
Invagination of epidermis with colarette
Keratin-filled crater
Atypical squamous epithelium with pale glassy appearance cytoplasm, often down to deep dermis
Neutrophil collections
Solar keratosis
Atypia along basal layer
Thinning of granular layer
Parakeratosis, hyperkeratosis
Amyloid stain
Crystal violet (magenta, metachromatic staining)
Congo red
Difference between sebaceoma and sebaceous adenoma
Sebaceoma - >50% basaloid cells
Sebaceous adenoma - <50% basaloid cells (basaloid cells at periphery, with sebaceous cells centrally)
Sebaceous carcinoma - more invasive, atypical mitoses, pleomorphism
Deep penetrating naevus stain (to differentiate from blue naevus)
Beta catenin
Stain for PEIN
P16
Muir Torre Stains/Mutations
MLH1, MSH2, MSH6, PMS2 (loss of)
Peripheral nerve sheath tumours
SOX10, S100 positive
Melan-A negative
Schwanomma - encapsulated, verocay bodies
Neurofibroma - circumscribed but not encapsulated
Ductal lumen stains
EMA
CEA
Ddx for syringoma
Desmoplastic trichoepithelioma
Microcystic adnexal carcinoma
Poroma
Growth of terminal duct cells
Circumscribed
Compact cuboidal keratinocytes, small monomorphous nuclei, scant eosinophilic cytoplasm
Stain: CEA positive
Ddx: seb k, porocarcinoma
Spiradenoma
Lobulated, circumscribed
Two types of basaloid cells - smaller palisaded at peripheries; adjacent larger spaced out basaloid cells
Scattered lymphoyctes
Cystic change/cyst like degeneration
Ddx: cylindroma, spiradenocarcinoma
Cylindroma
Two cell types, same as spiradenoma (smaller basaloid cells palisaded at peripheries; adjacent larger spaced out)
Occasional scattered lymphocyte superimposed
Duct formation
Jigsaw puzzle appearance
Ddx: spiradneoma
Hidradenoma papilliferum
Finger-like projections (papillary growth), apocrine differentiation, cuboidal columnar epithelium lining ducts, duct formation (maze-like)
ddx: syringocystadenoma papilliferum (plasma cells)
tubular apocrine adenoma (more simple arrangement of glands, less maze-like)
Hidradenoma
Clear cells, poroid cells, squamous cells, mucin
Duct formation
Sclerotic stroma
Xanthogranuloma
Spindle cells
Xanthomatisation
Touton giant cells
Superimposed lymphocytes, eosinophils
Stain: CD68 or CD163
Ddx: dermatofibroma
Granuloma faciale
Dense polymorphous dermal infiltrate (plasma cells, neutrophils, lymphocytes)
Perivascular accentuation, sometimes vascular damage
Red cell extravasation
Sweeping bands fibrosis
Grenz zone
Ddx: EED, Sweets
Langherans cell stains/markers
CD1A, langerin
Langerhans cells
Abundant pale eosinophilic cytoplasm
Footprint nucleus
Can get multiple nuclei
Warty dyskeratoma
Grains and corp ronds
Acantholysis and clefting
Acanthylotic dyskeratosis
Reticulated areas
ddx: Acontholytic dyskeratotic acanthoma
Spindle cell lipoma
Sharp demarcation, well circumscribed
Adipocytes
No septae
Mucin/myxoid change n stroma
Spindle cells
Scattered mast cells
Ropey collagen
CD34 will stain spindle cells
Angiolipoma
Uniform adipocytes
Small closely packed vessels, particularly peripherally
Naevoid melanoma - stains to help differentiate naevus and melanoma
KI67 - melanocytic proliferation
hmb45 (+ve in melanoma, -ve in naevi)
p16 (-ve in melanoma, +ve in naevi)
Beta catenin more diffusely positive in deep penetrating naevus than in melanoma
Glomus tumour
Basaloid cells - concentric surrounding vessels
Bland monotonous benign tumour of basaloid cells
Positive for smooth muscle actin
Negative for desmin
Glomangiomyoma
Circumscribed
Some spindle cells
Some smooth muscle differentiation
Vascular
Granuloma annulare
Interstitial infiltrate - histiocytes, somewhat circumscribed
Stain: alcian blue or colloidal iron for mucin
Ddx: NLD - less spared normal dermal collagen, more diffuse, less circumscribed, no mucin
Interstitial granulomatous dermatitis - also less circumscribed, more diffuse, more neutrophils
Types of dermatofibroma
Aneurysmal
Cellular
Atypical
Lipidised
Fibrocollagenous
Clear cell
Epithelioid
Haemosiderotic
Deep fibrous histiocytoma
Stains for melanin v haemosiderin
Schmorl’s stain - melanin
Prussian blue - haemosiderin
Xanthelasma
Xanthomatised histiocytes
CD68 CD163
Trichoblastoma
Most commonly associated with sebaceous naevus
Prominent cellular stromal component
Predominantly basaloid epithelial cells in nests with peripheral palisading
May show cribriform, rippled or solid patterns
Calcium stain
Von Kossa
Elastin stain
Verhoeff’s stain VVG
Elastosis perforans serpiginosa
Lymphoma stains
CD45 - Bs and Ts
CD3 - T cells
CD20 - B cells
Lung met
CK7
TTF1