Skin Flashcards by David Patton

Skin with perivascular inflammation comprised predominantly of neutrophils, with cellular debris, extravasation of red blood cells, vessel wall expansion and fibrinoid necrosis.

Leukocytoclastic vasculitis

Differential diagnosis:
Specific forms of leukocytoclastic vasculitis:
IgA vasculitis (Henoch-Schonlein purpura)
IgM/IgG vasculitis
Cryoglobulinaemia

Plan:
Correlate with clinical history and dermatologic impression (?drug/allergy/infection exposure ?renal/GI manifestations ?Hepatitis/HIV)
Correlate with any concurrent pathology testing (e.g. serum cryoglobulins)
Correlate with direct immunofluorescence findings (?specific pattern of staining)
Advice to clinician: Leukocytoclastic vasculitis is a general pattern of cutaneous small vasculitis and has multiple potential causes. Clinical correlation is required.

How well did you know this?

Not at all

Perfectly

Nodular dermal proliferation of highly pleomorphic spindle cells. May have melanoma in situ in overlying skin.

Spindle cell melanoma

Differential diagnosis:
Spindle cell SCC
Leiomyosarcoma
Angiosarcoma, Atypical fibroxanthoma (AFX)

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: S100 SOX10 and Melan A.
IPX to discount DDx: AE1/AE3 and CAM5.2, SMA and desmin, CD34, CD10 and CD68
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Poorly circumscribed dermal lesion with elongated spindle cells in abundant collagen, with scattered hyperchromasia/pleomorphism and lymphoid aggregates. May have melanoma in situ in overlying skin.

Desmoplastic melanoma

Differential diagnosis:
Dermal scar

Plan:
Correlate with clinical history and dermatologic impression (?history of previous biopsy/procedure)
IPX to support Dx: S100 and SOX10.
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Skin with nests of atypical melanocytes along dermoepidermal junction with pagetoid spread, without extension into dermis

Melanoma in situ

Differential diagnosis:
Extramammary Paget’s disease
Squamous cell carcinoma in situ

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: S100 SOX10 and Melan A.
IPX to discount DDx: CK5/6, CK7
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Skin with confluent nests of atypical melanocytes along dermoepidermal junction with pagetoid spread, and extending into dermis centrally without maturation and with dermal mitoses.

Superficial spreading melanoma

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: S100, SOX10, and Melan A.
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Polypoid/exophytic skin tumour with nests and sheets of atypical dermal melanocytes, with minimal junctional component, and no intraepidermal spread lateral to tumour

Nodular melanoma

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: S100, SOX10, and Melan A
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Nests of basaloid cells with frequent mitoses which undergo abrupt transition into ‘ghost’/’shadow’ cells. Associated calcification and foreign body giant cell reaction to keratin.

Pilomatrixoma

Plan:
Correlate with clinical history and dermatologic impression
No specific action required for this benign diagnosis

How well did you know this?

Not at all

Perfectly

Skin with dense band-like lymphocytic infiltrate, and with interface dermatitis (Civatte bodies in the basal layer and sometimes higher epidermis). The epidermis is also hyperkeratotic with prominent granular layer and irregular sawtooth acanthosis.

Lichen planus

Differential diagnosis:
Lichenoid keratosis (if solitary lesion)
Lichenoid or fixed drug eruption

Plan:
Correlate with clinical history and dermatologic impression
Special stains: PAS (highlight Civatte bodies)

How well did you know this?

Not at all

Perfectly

Skin/micosa with ill defined proliferation of bland, round to ovoid cells with eosinophilic granular cytoplasm. Overlying skin/mucosa may show pseudoepitheliomatous hyperplasia.

Granular cell tumour

Plan:
Correlate with clinical history
Examine further sections (e.g. for size, relation to margins)
IPX to support Dx: S100, CD68
No specific further action required for this benign diagnosis.

How well did you know this?

Not at all

Perfectly

Dermal tumour with nodules, sheets, nests, and trabeculae of small round blue cells with finely dispersed chromatin, nuclear moulding, and frequent mitoses, apoptoses, and crush artefact

Merkel cell carcinoma

Differential diagnosis:
Metastatic small cell neuroendocrine carcinoma

Plan:
Correlate with clinical history and radiology (?known neuroendocrine tumour in another site)
Examine further blocks (e.g. for total size, relation to margins)
IPX to support Dx: Synaptophysin, chromogranin, CK20 (expect perinuclear ‘dot-like’ positivity
IPX to discount DDx: TTF1, CDX2
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Well circumscribed dermal tumor composed of haphazardly arranged highly atypical spindle cells with abundant eosinophilic cytoplasm and occasional multinucleated cells

Atypical fibroxanthoma (AFX)

Differential diagnosis:
Pleomorphic dermal sarcoma (if bigger, deeper, with adverse features)
Spindle cell SCC
Leiomyosarcoma
Angiosarcoma
Spindle cell melanoma

Plan:
Correlate with clinical history and dermatologic impression
Examine further sections (e.g. for total size, relation to margins, any in-situ lesion in epidermis)
IPX to support Dx: CD10, CD68
IPX to discount DDx: AE1/AE3, SMA and desmin, CD34, S100 and SOX10
Next steps: Synoptic report

How well did you know this?

Not at all

Perfectly

Sharply demarcated epidermal lesion composed of bland basaloid keratinocytes with hyperpigmentation and keratin horn pseudocysts

Seborrhoeic keratosis

Plan:
Correlate with clinical history and dermatologic impression
No specific further action required for this benign diagnosis

How well did you know this?

Not at all

Perfectly

Pseudoepitheliomatous hyperplasia of the epidermis with suppurative dermal granulomatous inflammation containing septate, thick walled copper-coloured fungi (Medlar / muriform / sclerotic bodies).

Chromoblastomycosis

Plan:
Correlate with clinical history (?travel to endemic area ?slowly progressive lesion on extremity)
Correlate with concurrent microbiology investigations (culture) - if available, send fresh tissue for fungal culture
Special stains: Gram, PAS, GMS, ZN/modified ZN
Advice to clinician: A chronic fungal infection which is rare in Australia and most common in the tropics. Caused by multiple fungi found in wood, soil, and decaying plant material

How well did you know this?

Not at all

Perfectly

Well demarcated dermal proliferation of bland spindle cells in storiform architecture or short curly fascicles, with collagen trapping at periphery, overlying Grenz zone and epidermal hyperplasia / hyperpigmentation. Spindle cells have thin, elongated nuclei with pointed ends and eosinophilic cytoplasm

Dermatofibroma

Differential diagnosis:
Dermal scar
Blue naevus (if pigmented)
DFSP (if cellular)

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: Factor XIIIa
IPX to discount DDx: S100, CD34 (would be diffuse in DFSP, stain periphery only in DF)
No specific further action required for this benign diagnosis.

How well did you know this?

Not at all

Perfectly

Storiform architecture or short curly fascicles of monomorphic spindle cells in dermis with extensive subcutaneous involvement along fibrous septa (honeycomb pattern). No overlying epidermal hyperplasia.

Dermatofibrosarcoma protuberans

Differential diagnosis:
Cellular dermatofibroma
Nodular fasciitis
Solitary fibrous tumour

Plan:
Correlate with clinical history and radiology
Examine further sections (e.g. for size, relation to margins, fibrosarcomatous transformation)
IPX to support Dx: CD34 (expect diffuse positivity)
IPX to discount DDx: Factor XIIIa, STAT6
Next steps: Synoptic report, discuss at MDT

How well did you know this?

Not at all

Perfectly

Nodular endophytic squamous tumour with central keratin filled crater, and prominent underlying inflammatory infiltrate. Cells have glassy eosinophilic cytoplasm.

Keratoacanthoma

Plan:
Correlate with clinical history and dermatologic impression
IPX to support Dx: Not required
Advice to clinician: Some pathologists regard this as a seperate entity, while others regard it as a variant of well differentiated squamous cell carcinoma. They have a characteristic clinical appearance and natural history of spontaneous regression.

How well did you know this?

Not at all

Perfectly

Skin lesion with large nests of (possibly atypical looking) melanocytes in dermoepidermal junction and dermis, maturing with depth and breaking up into single melanocytes at base. DEJ shows eosinophilic hyaline globules (Kamino bodies) and clefting artefact from melanocyte nests

Spitz naevus

Plan:
Correlate with clinical history and dermatologic impression
Examine further sections (e.g. for total size, relation to margins, areas of atypical features)
IPX to support Dx: S100, HMB45 (expect HMB45 to show maturation, with decreased staining in the deeper parts of the lesion)
No specific further action required for this benign diagnosis.

How well did you know this?

Not at all

Perfectly

Uniform acanthosis (epidermal hyperplasia with elongation of rete ridges), with ‘suprapapillary thinning’ (thinning of epidermis over dermal papillae), associated with parakeratosis, and collections of neutrophils (Munro’s microabscesses) within parakeratin layer. Dermis shows mild perivascular and interstitial infiltrate composed predominantly of lymphocytes, and dilated/tortuous capillaries within the dermal papillae.

Psoriasis

Differential diagnosis:
Fungal infection
Psoriasiform drug reaction
Lichen simplex chronicus
Subacute spongiotic dermatitis (e.g. eczema, allergic contact dermatitis, nummular dermatitis)

Plan:
Correlate with clinical history and dermatologic impression (?distribution and evolution of lesions ?drug/infectious/irritant exposures ?chronic scratching)
Examine deeper levels
Special stains: PAS and GMS (for any fungal elements)

Skin with mild perivascular lymphocytic inflammation in dermis and and lymphohistiocytic inflammation along septa of subcutaneous fat. Early lesions may show ‘Miescher radial granuloma’ (A cluster of small histiocytes radially arranged around a central cleft). Older lesions show widening of septa with fibrosis and multinucleated giant cells.

Erythema nodosum

Plan:
Correlate with clinical history (?tender erythematous plaque in pre-tibial area ?infectious/drug exposure ?systemic disease)
Advice to clinician: Usually self limiting, may be idiopathic or due to a wide range of antecedent causes.

Skin with acute/chronic inflammatory changes and naked hair shafts

Pilonidal sinus

Plan:
Correlate with clinical history (?chronic abscess/sinus formation in gluteal cleft)
No specific action required for this benign diagnosis.

Skin with haphazardly arranged, thick hyalinized collagen bundles within the dermis, surrounded by bland fibroblasts

Keloid scar

Plan:
Correlate with clinical history and dermatologic impression (?history of biopsy/procedure)
No specific further action required for this benign diagnosis.

Skin tumour formed of small nests of basaloid cells with irregular shapes that fit together in a puzzle pattern, each surrounded by thick pink basement membrane material which can also form droplets within nests.

Cylindroma

Differential diagnosis:
Spiradenoma (‘blue balls’)

Plan:
Correlate with clinical history and dermatologic impression (?head/neck location ?Brooke-Speigler syndrome)
IPX to support Dx: Not required
Advice to clinician: May be sporadic, or assiociated with Brooke-Speigler syndrome, where multiple lesions occur. Clinical correlation is required.

Well circumscribed nodule in dermis with bland ducts, tubules, and islands of epithelial /myoepithelial cells set within a chondromyxoid stroma.

Chondroid syringoma (cutaneous mixed tumour)

Plan:
Correlate with clinical history and dermatologic impression (?head/neck location)
IPX to support Dx: Not required
No specific action required for this benign diagnosis.

Dermal cyst lined by stratified squamous epithelium, with granular layer, containing lamellated (‘flaky’) keratinous material in the cyst lumen.

Epidermal inclusion cyst

Plan:
Correlate with clinical history and dermatologic impression
No specific action required for this benign diagnosis

Dermal proliferation of bland, spindle shaped melanocytes admixed with melanophages in a dense collagenous background

Blue nevus Differential diagnosis: Dermatofibroma (pigmented) Plan: Correlate with clinical history and dermatologic impression IPX to support Dx: S100, SOX10, and Melan-A. IPX to discount DDx: Factor XIIIa No specific further action required for this benign diagnosis

Skin with poorly circumscribed masses of macrophages (which may be foamy) in the dermis, with few / no lymphocytes, and predilection for nerves, vessels, and skin adnexa.

Lepromatous leprosy Plan: Correlate with clinical history and dermatologic impression (?travel or migration from endemic area) Correlate with concurrent microbiology investigations (e.g. PCR). If not performed, parrafin block can be used for PCR. Special stains to support Dx: Modified ZN (Wade-Fite) stain Advice to clinician (urgent via phone): This is a rare disease in Australia and patient may require urgent treatment. Patient may also require infectious diseases precautions (public health implications)

Band like infiltrate of lymphocytes beneath epidermis, with prominent intraepidermal lymphocytes out of proportion to degree of spongiosis (epidermotropism). Lymphocytes are hyperchromatic with nuclear contour irregularity (cerebriform nuclei). May form small aggregates within epidermis (Pautrier microabscesses)

Mycosis fungoides Differential diagnosis: Inflammatory skin disease (e.g. psoriasis, atopic dermatitis, drug reaction, fungal/parasitic infection) Sezary syndrome Systemic T cell neoplasm (T cell leukaemia/lymphoma) Plan Correlate with clinical history and radiology Examine deeper levels Special stains: DPAS IPX to support Dx: CD4, TCR-beta, CD2 (positive for CD4 and TCR-beta with loss of CD2 would support MF) Next steps: Discuss at MDT

Nests and cords of bland melanocytes within dermis, with maturation towards the deep aspect. No melanocytes seen within dermoepidermal junction

Benign intradermal naevus Plan: Correlate with clinical history and dermatologic impression Examine further blocks (e.g. for total size, relation to margins) IPX to support Dx: S100, SOX10, MelanA, HMB45 (expect HMB-45 to show decreased staining deeper in lesion) No specific further action required for this benign diagnosis

Sharply circumscribed vulval/perianal lesion with maze-like glandular and papillary architecture without connection to overlying epithelium. The glands are lined by an inner layer of cuboidal cells and an outer layer of myoepithelial cells. Mitotic figures are rare

Hidradenoma papilliferum Plan: Correlate with clinical history Examine further blocks (e.g. for total size, relation to margins) No specific further action required for this benign diagnosis

Skin with epidermal hyperplasia forming a cup-shaped verrucous lesion with a central umbilication. The cytoplasm of the keratinocytes contains large eosinophilic viral inclusions (Henderson-Paterson bodies).

Molluscum contagiosum

Name of viral inclusions in molluscum contagiosum

Henderson-Paterson bodies

Skin with numerous small ducts in the dermis embedded in a fibrous stroma. Ducts are lined by two rows of flattened to cuboidal epithelial cells. A characteristic feature is the presence of comma-shaped or tadpole-like ducts due to an elongated "tail" of epithelial cells extending from the duct. The ductal lumens often contain amorphous, eosinophilic material. There is usually no connection to the overlying epidermis.

Syringoma Differential diagnosis Microcystic adnexal carcinoma (if poorly circumscribed, deeply infiltrative, perineural invasion) Plan Correlate with clinical history and dermatological impression (?typical location on eyelid or vulva) Examine further blocks (for evidence of MAC) No specific action required for this benign diagnosis

Ear lesion in old man with funnel shaped ulcer with fibrin and necrobiotic collagen, extending down to cartilage with superficial cartilage erosion

Chondrodermatitis nodularis helicis Differential diagnosis Gout tophus Plan Correlate with clinical history (?painful lesion, history of chronic pressure) No specific action required for this benign diagnosis

Genital skin lesion with papillary architecture, hyperplastic squamous epithelium with acanthosis, hyperkeratosis, and koilocytes (squamous cells with perinuclear halos and wrinkled nuclei) in the upper layers.

Condyloma acuminatum (genital wart)

Genital/anal skin lesion with psoriasiform epidermal hyperplasia and dense inflammatory infiltrate in dermis rich in plasma cells

Condyloma lata (syphilis) Differential diagnosis Psoriasis Lichen planus Plan Correlate with clinical history (?sexual exposure ?serological testing for syphilis) Special stains to support diagnosis: Warthin Starry (highlight spirochete organisms) IPX to support diagnosis: Treponema pallidum In case of positive for syphilis, would inform clinician of need for treatment and partner notification / tracing

Skin with superficial perivascular inflammation rich in eosinophils. Mites with dorsal spines can be visualised in the stratum corneum.

Scabies Plan Advice to clinician: Highly contagious, and may require treatment with permethrin cream

Scrotal lesion with multiple nodules in the dermis composed of amorphous, basophilic calcium deposits, often surrounded by a foreign body giant cell reaction and fibrosis.

Scrotal calcinosis

Skin with dermal deposition of yellow-brown, banana-shaped pigment assiociated with marked elastosis

Ocronosis Plan Advice to clinician: Can be caused by various medications, most commonly topical hydroquinone

Genital lesion with ulcerated epidermis/mucosa, often with intraepidermal vesiculation (acantholysis). Epithelial cells at the ulcer edge or vesicle base/roof show multinucleation with nuclear molding, peripheral margination of chromatin, and ground-glass intranuclear inclusions. An associated dermal/submucosal inflammatory infiltrate is typically present.

Herpes simplex virus (HSV) genital ulcer Differential diagnosis: VZV Plan: Correlate with clinical history (?sexual exposure) Correlate with concurrent microbiology investigations (e.g. viral swab for PCR) IPX to support Dx: HSV1 and HSV2 (if required)

Scalp tumour with cystic invaginations and papillary projections lined by a double layer of epithelium (inner tall columnar cells with apical snouts, and outer cuboidal myoepithelial cells). The fibrovascular stroma contains a dense infiltrate of plasma cells. May arise from nevus sebaceous.

Syringocystadenoma papilliferum Plan: Correlate with clinical history and dermatologic impression Examine further blocks (e.g. for total size, relation to margins, other assiociated adnexal neoplasm) No specific action required for this benign diagnosis.

Skin tumour with islands of basaloid cells surrounded by stroma, which pushes into / indents the islands - 'papillary mesenchymal bodies.' Unlike BCC, the stroma tightly hugs the nests (no stromal retraction) and lacks mucin, although the nodules of stroma themselves may cleft from the adjacent dermis

Trichoepithelioma Differential diagnosis: Trichoblastoma (if bigger, deeper)

Term for stroma pushing into/indenting islands of basaloid cells in trichoepithelioma

Papillary mesenchymal bodies

Dermal cyst lined by stratified squamous epithelium which lacks a granular layer and shows a wavy, eosinophilic cuticle. Sebaceous glands are present within the cyst wall.

Steatocystoma