Chapter 27 - Skin Flashcards
Describe the morphology of melanocytes
Neuralish, dendritic morphology and stain with S-100. Also produce melanin pigment but do not carry much themselves.
What is a melanophage?
A spindly mancrophage which appears melanotic because they are consuming melanin.
Desecribe the normal course of a melanocytic nevus.
Begins as a lentigo simplex at the dermoepidermal junction. Proliferates into nests (theques) as a junctional nevus. Then migrates into the dermis with loss of the junctional component (intradermal nevus).
What is a compound nevus?
A junctional nevus with a dermal component.
Recall some benign or reassuring features of nevi.
Symmetry
Size <3mm
Lateral borders consisting of nests (not individual cells)
Lack of atypia
Maturation into the dermis
Chunky brown-black pigment
What is a blue nevus?
A common nevus consisting of a diffuse scattering of dendritic single melanocytes mixed with melanophages.
What is a Spitz nevus?
A cirumscribed and symmetric nevus found on the head & neck of children.
Melanocytes may be large, spindled, pleomorphic, or even show mitoses. Look for eosinophilic Kamino bodies.
What are some features of acral & genital nevi?
Of congenital nevi?
Acral and genital nevi are allowed some atypical features (pagetoid spread, lengitinous growth), but no cytologic atypia.
Congenital nevi should track down the adnexal structures.
What are the four features of architectural disorder in dysplastic nevi?
Lentiginous spread of atypical melanocytes (along DEJ)
Shouldering (lentiginous component wider than dermal component)
Bridging of rete (nests attached to adjacent rete ridges fuse)
Fibroplasia (featuring of dermal collagen)
What are the four features of cytologic atypia in dysplastic nevi?
Hyperchromatic nuclei (increased N:C)
Large red nucleoli
Accumulation of dusty grey-brown melanin
Atypical mitoses
What is lentigo maligna?
What is Melanoma in situ?
Lentigo: Malignant melanocytes proliferating only along the DEJ.
In situ: Above, and percolating up through the epidermis in a pagetoid fashion
What feature is required to diagnose malignant melanoma?
Distinguish between superficial spreading and nodular melanomas.
Invasion through the DEJ into the dermis (and pagetoid epidermal spread)
Superficial spread grows horizontally but also involves the dermis. Nodular is primarily growing down into the dermis.
Recall some morphologic feature suspicious for melanoma.
Asymmetry
Discohesive nests
Discohesive cells & pagetoid spread
Band-like associated lymphocytes
Cytologic atypia
Lack of deep maturation
Melanocytic necrosis
What criteria must be included on sign out of a melanoma?
Depth (Breslow’s in hundredth of a millimeter, Clark’s related to the histologic levels)
Presence or absence of ulceration
Margin status
What are desmoplastic and spindle cell melanoma?
Melanoma with spindly/sarcomatoid melanocytes. Desmoplastic is also sparsely cellular in a dense fibrotic background. Look for clumps of lymphocytes…
What is acral lentiginous melanoma?
A melanoma that is characterized by prominent lengitinous growth, and can be hard to distinguish from an acral nevus.
What features of metastatic lesions suggest melanoma?
Alveolar (nested) architecture
Large cells with big nuclei and red nucleoli
Occasional melanin pigment
Recall the utility of S-100, HMB-45, and Melan-A in diagnosis of melanoma.
S-100 stains all melanomas. Not helpful in lymph nodes (FDCs)
HMB-45 does not stain spindled melanomas. Generally lost deep in a melanoma. Also stains PEComas & angiomyolipoma.
Melan-A does not stain spindled or desmoplastic melanomas.
What is solar elastosis?
Solar lentigo?
Elastosis: Accumulation of grey wispy damaged elastin in the dermis
Lentigo: A finger-like proliferation of hyperpigmented rete growing into the epidermis.
What are the defining features of actinic keratosis?
Squamous atypia of varying thickness
Keratin becomes pink and hyperkeratotic, with sparing of keratin above the hair follicles.
Underlying solar elastosis
What is bowenoid actinic keratosis?
Full-thickness atypia without invasion.
What dermal entities can be categorized as carcinoma in situ?
Actinic keratosis & bowenoid actinic keratosis
Bowen’s disease: In non sun-damaged skin and does not spare hair follicles
Bowenoid papulosis: HPV-related lesion of genital sites
What are the features of basal cell carcinoma?
Lobules of small, blue, basal-type keratinocytes with peripheral palisading
Formation of clefts between tumor nests and stroma
Desmoplasia, focal keratinization, or mucin production
Recall three or so subtypes of basal cell carcinoma.
Nodular: Usual type
Superficial multicentric: Hangs off epidermis like stalactites
Sclerosing: Prominent desmoplastic response
Describe the usual morphology of seborrheic keratoses.
Hyperkeratotic, orthokeratotic lesion with a markedly thickened epidermis. Features horn cysts (whorls of orthokeratin) and some pigment and inflammation. No atypia.
Describe the morphology of verruca vulgaris.
Church-spire epidermal proliferation with overlying hyper/parakeratosis. Has koilocytes.
What are eccrine poroma / acrospiroma / hidradenoma?
Tumors of sweat ducts composed of keratinocyte-like cells tha tform ducts. Streamy, pale, and disorganized. Like usual ductal hyperplasia in breast.
What are eccrine spiradenomas?
“Blue cannonballs in the dermis”, consisting of two basaloid cell lineages with noticeable cords and droplets of hyaline basement membrane substance
What is a cylindroma?
What is a syringoma?
An adnexal tumor with basaloid nests in the dermis but a mosaic shape to the nests.
A collection of round, dilated tubules with tadpole-like appearance
What is a trichoepithelioma?
What is microcystic adnexal carcinoma?
A benign tumor of hair follicle that resembles BCC but with horn cysts, hair formation, fibrotic stroma and lack of clefting.
A cancer of sweat gland that resembles syringoma but with deep infiltration into the dermis.
What is an epidermoid cyst?
What is a pilar cyst?
Epidermoid: Lined by mature squamous epithelium with a granular layer and filled with flaky keratin.
Pilar: Lined by plump keratinocytes with no granular layer filled with compact dense keratin.
Describe the normal morphology of dermatofibroma.
What is its malignant counterpart?
Ill-defined blue haze in the dermis made of tiny swarming nondescript cells with overlying hyperpigmentation/hypertrophy.
Dermatofibrosarcoma protuberans
Describe the normal morphology of neurofibromas.
Pale/grey nodules in the dermis composed of cells with wavy nuclei and wavy collagen.
Describe the normal morphology of hemangiomas.
What is its malignant counterpart?
Proliferation of well-formed, dilated capillaries in teh dermis.
Angiosarcoma, which is more cellular and has anastomosing channels lined with plump cells.
Describe the morphology of Kaposi’s sarcoma.
Of pyogenic granuloma?
Simulates hemangioma, very hard to spot in early stages.
Lobular, circumscribed lesion that is very cellular and inflamed.
How does the epidermis appear folowing acute damage or inflammation?
Edema (spongiosis), which can be severe enough for form intradermal vesicles. Followed by hyperplasia (acanthosis) and possibly hyperkeratosis.
What is interface dermatitis, and what are its two patterns?
Inflammation of the basal keratinocyte layer.
Lichenoid: Intense lymphocytic infiltrate at the DEJ.
Vacuolar: Vacuolar degeneration of the basal cells
What is acantholysis?
Usually antibody-mediate destruction of the intercellular junctions. Results in coalescence of bullae.
What is the most simple pattern of dermal inflammation?
What if it progresses and features neutrophils?
Perivascular lymphocytic inflammation
Vasculitis
What is leukocytoclastic vasculitis?
Vessels show fibrinoid necrosis and nuclear debris
What do neutrophilic infiltrates, granulomas, or dense lymphocytic infiltrates in the dermis suggest?
Neutrophilic: eg Sweet’s syndrome
Granulomatous: Infection, foreign body response, sarcoidosis, granuloma annulare
Lymphocytes: Consider cutaneous T-cell lymphoma
What are the two forms of panniculitis? Give examples.
Septal: Inflammation is mostly in the fibrous septae between fat. eg Erythema nodosum.
Lobular: Fat itself is inflamed. eg Lupus profundus.
Normal skin
- Normal melanocyte with clear halo of cytoplasm
- Pigmented basal keratinocyte
- Typical orthokeratin
Melanophages in an intradermal nevus
Arrowhead: Nevus cells
Arrow: Melanophages
Lentigo simplex in acral skin
Arrows: Linear proliferation of melanocytes along DEJ.
Compound nevus
Arrow: Nest of nevocellular cells at the DEJ
Arrowhead: Maturing nevus cells in the dermis
Intradermal nevus
More mature cells at base (arrowhead) than at surface (arrow).
Blue nevus
Arrow: Elongated, fusiform cells scattered in dermal collagen
Spitz nevus
Arrow: Large, spindled melanocytes at the DEJ
Arrowhead: Pagetoid spread of melanocytes in the epidermis
Dysplastic nevus
Arrow: Spindled melanocytes bridging the rete
Arrowhead: Trailing of single melanocytes at the edges
Inset: Cytologicallya typical melanocytes
Melanoma
Top: Pagetoid spread of melanocytes (arrowheads)
Bottom: Deep dermal melanocytes with cytologic atypia (arrowhead) and mitoses (arrow).
Desmoplastic melanoma
Arrow: Appearance of hypocellular scar in dermis
Arrowhead: Collection of lymphocytes
Inset: Enlarged and hyperchromatic melanocytes within the “scar”
Solar elastosis
Arrow: Collagen replaced by gray-blue strands of elastin
Solar lentigo
Arrow: Prominent rete with increased basal pigmentation and underlying solar elastosis
Actinic keratosis
- Disorganized and enlarged nuclei
- Atypical mitoses
- Overlying hyperkeratosis/parakeratosis
- Underlying solar elastosis
Squamous cell carcinoma
Left: Superficially invasive SqCC
Arrow: Deep keratinization (invasive nest)
Arrowhead: AK-like changes in the overlying epidermis
Right: Same, high-power
Asterisk: Keratin pearl
Arrow: Infiltrating single cell
Basal cell carcinoma
Arrow: Clefting of tumor cells from the stroma
Arrowhead: Prominent palisading at periphery of nests
Seborrheic keratosis
Arrow: Horn cysts (entrapped keratin)
Arrowhead: Hyperkeratosis (but no parakeratosis!)
Verruca vulgaris
Arrow: Epidermis heaped into tall spires, topped with hyperkeratosis and parakeratosis.
Poroma
Arrow: Epidermis, continuous with lesion
Arrowhead: Tumor cells that are uniform, small and round, sometimes with rudimentary duct spaces
Eccrine spiroadenoma
“Cannonballs in the dermis” composed of small round bland cells. Cords of hyaline pink basement membrane material (arrow).
Syringoma
Arrow: Small tubules with comma-like tails in the dermis
Microcystic adnexal carcinoma
Arrow: Horn cysts
Arrowheads: Small pale nests deeply infiltrating the dermis
Left: Trichilemmal cyst (no granular cell layer, dense “wet” keratin)
Right: Epidermoid cyst (granular cell layer, flaky “dry” keratin)
Dermatofibroma
Arrowheads: Poorly circumscribed blue haze of fibroblasts
Arrow: Overlying prominent and hyperpigmented rete
Inset: Infiltrating cells with small round-to-oval nuclei.
Dermatofibrosarcoma protuberans
Note increased cellularity and prominent storiform architecture
Neurofibroma
Arrowhead: Poorly defined dermal tumor that is paler than surroundings
Inset: Tapering, undulating nuclei (arrow) and wavy collagen fibers (arrowhead)
Capillary hemangioma
Note collection of discrete, well-formed and dilated capillaries
Kaposi’s sarcoma
Arrowheads: Slit-like vascular spaces with bland endothelium
Arrow: Accentuation of spaces around existing vasculature (“promontory sign”)
