Difference between revisions of "Dermatopathology"
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Revision as of 18:41, 9 September 2011
Dermatopathology is the pathology of skin.
Pathology is a significant part of dermatology and dermatologists spend five years in residency. So, it is a huge area.
Layers of the skin
- Epidermis - outer most layer, avascular, separated from dermis by a basement membrane, epithelial tissue.
- Dermis - below the epidermis, vascular, separated from the epidermis by a basement membrane, connective tissue.
- Subdermis - below the dermis, connective tissue.
Layers of epidermis
Epidermis layers - from the surface to epidermal-dermal junction:
- Stratum corneum.
- Stratum lucidum.
- Present only in "thick" skin.[1]
- Stratum granulosum.
- Stratum spinosum (aka prickle layer).
- Stratum basale (germinativum).
Mnemonic: Corn Lovers Grow Several Bales.
Adnexal structures
The top five structures of the skin:[2]
| Structure / Attribute | Histomorphology | Function | IHC | Other | Image |
| Eccrine gland | clusters of tubular structures, pale cytoplasm | thermoregulation (cooling) | CK7+, CEA+, CAM5.2+, EMA+ | ? | ? |
| Apocrine gland | apical snouts, tubular structures | ear wax, body odor | ? | ? | ? |
| Sebaceous gland | clusters of cells side-by-side, pale fluffy cytoplasm | grease hair, sexual lubrication | ? | assoc. with hair follicle | ? |
| Hair follicle | linear structure | keep individual warm | ? | assoc. with sebaceous glands | ? |
| Nail | epidermal structure | ? look pretty | ? | ? | ? |
Ducts vs. glands:[3]
- Eccrine glands - spindle-shaped myoepithelial cells surround luminal cells.
- Eccrine ducts - cuboidal type subepithelial cells.
Common terms
- Acanthosis = thickening of the prickle layer (stratum spinosum) of epidermis.[4]
- Parakeratosis = retention of nuclei in the stratum corneum, normal in mucous membranes
- Dyskeratosis = abnormal keratinization, often refers to keratinization below the stratum granulosum; keratinization above may be abnormal (dependent on body site).
- Spongiosis = epidermal intercellular edema;[5] cells appear to have a clear halo around 'em.
Images:
Skin diseases
Cancer
Main article: Dermatologic cancer
Skin cancer is very common. The basic DDx of a malignant skin lesion is:
- Squamous cell carcinoma (SCC).
- Basal cell carcinoma (BCC).
- Malignant melanoma.
- Metstases.
Non-malignant disease
Main article: Non-malignant skin disease
Non-malignant skin disease is common. It is the domain of dermatologists. It can be scary for general anatomical pathologist because the differential diagnosis is often broad, and, it's generally not something the general anatomical pathologist sees a lot of.
Bullous diseases, e.g. pemphigus vulgaris, is dealt with in the bullous disease article.
Common entities in tables
Non-malignant non-cystic
| Entity | Key histologic feature | Other features | Clinical | Stains/IHC | DDx | Other | Image |
|---|---|---|---|---|---|---|---|
| Seborrheic keratosis (SK) | horn cysts (intraepidermal collections of keratin) | hyperkeratosis, brown granular material at the DE junction, sharply demarcated | stuck on appearance | none | Fibroepithelial polyp | Leser–Trélat sign = many SKs in malignancy | (WC) |
| Dermatofibroma | fibrous bundles esp. at edge of lesion | "dirty fingers" = acanthosis + basal keratinocyte hyperpigmentation | +/-trauma Hx | CD34-, Factor XIIIa+ | DFSP | very common | (pacificderm.org) |
| Fibroepithelial polyp (skin tag) | on a stalk (epithelium on 3+ sides) | no horn nests, no hyperkeratosis | raised lesion | none | seborrheic keratosis | very common | (dermatlas.med.jhmi.edu) |
| Lipoma | mature adipocytes - uniform size | var. of size may be seen, should prompt search for lipoblasts | mobile subcutaneous mass | S100 (???) | liposarcoma | variants: angiolipoma (blood vessels), myolipoma (muscle) | (ahajournals.org) |
| Angiofibroma | fibrotic dermis, dilated capillaries | enlarged (stellate fibroblasts) | dome-shaped - face, boys & nosebleeds (nasopharyngeal angiofibroma) | Stains/IHC | DDx | may be associated with tuberous sclerosis | Angiofibroma (drdittmar.lu) |
| Keloid | thick collagen bundles - surrounded by paler staining fibroblasts | replaces adnexal structures | site of previous trauma, esp. in blacks | none | dermatofibroma (???) | Other ? | (ucsf.edu). |
| Neurofibroma | bland spindle cells | mixed with collagen (???) | may be associated with neurofibromatosis | S100+ (???) | dermal nevus (???) | Other ? | (WC) |
| Keratoacanthoma | keratin plug, glassy pink cytoplasm, pushing downward growth | minimal/no nuclear atypia | grow rapidly then involute | none | squamous cell carcinoma | some don't believe in the entity | (WC) |
| Molluscum contagiosum | suprabasilar cells with abundant granular eosinophilic cytoplasm | small peripheral nucleus | polypoid lesion (?) | none (?) | DDx (?) | favourite exam case | (WC) |
| Granuloma annulare | dermal palisading granuloma around necrotic collagen | mucin in centre of lesion, (peripheral) chronic inflammatory cells | benign, self-limited | none (CD68?) | necrobiosis lipoidica, rheumatoid nodule | Other ? | (dermaamin.com) |
| Juvenile xanthogranuloma (JXG) | Touton giant cells - multi-nucleated cells where nuclei are distributed around the cell periphery forming a ring | abundant cytoplasm | children | CD68+, CD1a-, CD207- | Langerhans cell histiocytosis | Other ? | (WC) |
| Verruca vulgaris | hypergranulosis (thick granular layer) + keratohyaline granules | hyperkeratosis (thick s. corneum), acanthosis (thick s. spinosum), rete ridges lengthened (~7-10x normal), large vessels at DE junction, koilocytic change (???) | raised lesions, classically on hand | none (p16+?) | DDx ? | caused by HPV | (WC) |
| Condyloma acuminatum | koilocytes | parakeratosis, long folded rete ridges (papillomatosis) - pseudopapillary look | genital lesion | none (p16+) | DDx | Other | (WC) |
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Non-malignant cystic
| Entity | Key histologic feature | Other features | Clinical | Stains/IHC | DDx | Other | Image |
|---|---|---|---|---|---|---|---|
| Epidermal cyst | keratin surrounded by epidermis, epidermis has granular layer | cyst | none | pilar cyst | Other? | (ucsf.edu) | |
| Pilar cyst | keratin surrounded by epidermis, epidermis has no granular layer | cyst | none | epidermal cyst | Other? | Image? |
Pre-malignant
| Entity | Key histologic feature | Other features | Clinical | Stains/IHC | DDx | Other | Image |
|---|---|---|---|---|---|---|---|
| Actinic keratosis | epidermal atypia, esp. (basal) nuclear enlargement | var. of size, shape and staining | yellow-brown scaly | none | squamous carcinoma | squamous carcinoma | (WC) |
Common malignant
| Entity | Key histologic feature | Other features | Clinical | Stains/IHC | DDx | Other | Image |
|---|---|---|---|---|---|---|---|
| Basal cell carcinoma (BCC) | basaloid cells with peripheral palisading, artificial cleft | myxoid stroma | raised, pearly, telangiectasia | none (???) | trichoepithelioma | assoc. nevoid basal cell carcinoma syndrome, Bazex syndrome | (ucsf.edu) |
| Squamous cell carcinoma (SCC) | nuclear enlargement, eosinophilic cytoplasm, central nucleus | small nucleolus, intercellular bridges | flaky appearance | p63+, HMWK+ (???) | keratoacanthoma, Paget disease - EMPD & PDB, Melanoma, Toker cell hyperplasia | Other | (WC) |
| Malignant melanoma | nuclear atypia (nucleoli), spindle and/or epithelioid morphology | mitoses (esp. deep), +/-pigment, +/-nested arch., asymmetry, upward spread (into epidermis), epithelioid m. deep | ABCD = Asymmetry, Borders poor demarc., Colour dark, Diameter large | S100+, Melan A+, HMB-45+, microphthalmia+, tyrosinase+ | melanocytic lesions | may be familial, dysplastic nevus | (WC) |
Less common malignant
| Entity | Key histologic feature | Other features | Clinical | Stains/IHC | DDx | Other | Image |
|---|---|---|---|---|---|---|---|
| Kaposi sarcoma | vascular spindle cell lesion | hyaline globules (intracytoplasmic) | often HIV/AIDS | HHV-8 | Masson's hemangioma, angiosarcoma | Other | (WC) |
| Cutaneous T-cell lymphoma (mycosis fungoides) | single lymphocytes in epidermis ("lymphocyte exocytosis") | lymphocyte nests in the epidermis ("Pautrier microabscesses"), short arrays of lymphocytes along the basal layer of the epidermis ("epidermotropism") | Clinical | CD45, CD4 | B cell lymphoma (?) | Other | (WC) |
| Atypical fibroxanthoma | dermal lesion with marked nuclear atypia | multinucleated cells, mitoses, vacuolated cytoplasm | old men, head and neck | p63-, 34betaE12-, S100-, desmin- | sarcomatoid squamous carcinoma, melanoma, leiomyosarcoma | some classify this as benign; thought to be related to undifferentiated pleomorphic sarcoma | (cdlib.org)[6] |
| Merkel cell carcinoma | neuroendocrine nuclear features (stippled chromatin, no nucleolus), scant cytoplasm | +/-nuclear moulding, usu. intermediate cell size | Merkel cell polyomavirus associated, usu. head & neck or extremities | CK20+, EMA+ | cutaneous Ewing sarcoma, basal cell carcinoma, (dermal) lymphoma | rare, aggressive | (bccancer.bc.ca) |
| Dermatofibrosarcoma protuberans (DFSP) | spindle cell tumour with storiform pattern, tumour often contains adipocytes | dermal tumour with preserved adnexal structures | locally aggressive | CD34+, factor XIIIa- | dermatofibroma, solitary fibrous tumour (usu. deeper) | rarely metastases, characteristic translocation: t(17;22)(q22;q15) COLA1/PDGFB; may transform to fibrosarcoma | (WC) |
Presentations
Leukoplakia
DDx:[7]
- Vitiligo (loss of pigment).
- Inflammation.
- Chronic dermatitis.
- Psoriasis.
- Neoplasia.
- Vulvar intraepithelial neoplasia.
- Paget disease.
- Invasive carcinoma.
- Other.
Skin disease and systemic conditions
Tabular list
| Entity | Disease/syndrome | Key histologic feature | Image |
|---|---|---|---|
| Acanthosis nigricans | diabetes mellitus, malignancy | basal cell hyperpigmentation, hyperkeratosis, prominent rete ridges | (cdlib.org) |
| Trichilemmoma | Cowden disease | ||
| Angiokeratoma | Fabry disease | ||
| Dermatitis herpetiformis | Celiac disease | subepidermal bullous disease | |
| Angiofibroma | tuberous sclerosis |
Acanthosis nigricans
Associated with: diabetes mellitus,[8] malignancy.[9]
Microscopic
Features BPH:[9]
- Basal cell hyperpigmentation.
- Prominent rete ridges.
- Hyperkeratosis.
Images:
Others
- Dermatitis herpetiformis: gluten enteropathy (celiac disease), thyroid disease, intestinal lymphoma.[10]
- Pemphigus vulgaris: thymoma, myasthenia gravis, malignancy.[11]
References
- ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 1. ISBN 978-0443066542.
- ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 4-8. ISBN 978-0443066542.
- ↑ HJ. 27 Feb 2009.
- ↑ http://dictionary.reference.com/browse/acanthosis
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 1230. ISBN 0-7216-0187-1.
- ↑ Vandergriff, TW.; Reed, JA.; Orengo, IF. (2008). "An unusual presentation of atypical fibroxanthoma.". Dermatol Online J 14 (1): 6. PMID 18319023.
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 1065. ISBN 0-7216-0187-1.
- ↑ URL: http://www.emedicine.com/derm/topic1.htm, URL: [1].
- ↑ 9.0 9.1 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 596. ISBN 978-1416054542.
- ↑ TN07 D23.
- ↑ TN07 D23.