Dr. Jared Gardner collaborates with Stony Brook Dermatology residents to review eight unknown dermatopathology cases. The session explores a wide spectrum of cutaneous findings, emphasizing classic histological features and clinical correlation required for definitive diagnosis. Cases range from common mucosal lesions (labial melanotic macule) and robust inflammatory processes (pseudo-lymphoma-like tattoo reaction) to rare benign tumors (perineuroma, including discussion of its sclerosing variant) and reactions to systemic conditions. Notable highlights include a textbook example of zinc deficiency (acrodermatitis enteropathica), the subtle signs of acute pressure-induced ischemia (coma blister) identified by eccrine coil necrosis, and complex drug effects involving chemotherapy-induced epidermal dysmaturation and syringometaplasia. The session concludes with a review of the varied, non-specific pathology of hidradenitis suppurativa.
Dermatopathology Unknown Cases Review with Dr. Jared Gardner
Details: Pigmented macule on the lip of a 40-year-old woman. Histology shows prominent basal layer hyperpigmentation, pale glycogenation of keratinocytes (indicative of mucosa), and pigment drop-out into the submucosa. Melanocytes are scattered, not nested.
Takeaway: A benign finding, analogous to lentigo simplex. The presence of skeletal muscle bundles confirms the location is the oral lip (rather than genital labia, which would contain smooth muscle).
4:27 Case 2: Tattoo Reaction (Pseudo-lymphoma Pattern)
Details: Excision specimen from a 35-year-old man. Features a dense inflammatory infiltrate of lymphocytes and histiocytes in the dermis, mimicking a pseudo-lymphoma. Key finding is the presence of red (cinnabar) and black tattoo pigment granules. The reaction exhibits dramatic epidermotropism (lymphocytes in the epidermis) and pseudoepitheliomatous hyperplasia (PEH).
Takeaway: A brisk tattoo reaction, often caused by mercuric red pigment. The histology can strongly mimic mycosis fungoides (due to epidermotropism) or squamous cell carcinoma (due to PEH), necessitating careful clinical correlation.
Details: Firm papule on the finger, initially queried as a cyst. Histologically, it is a dermal nodule of thin, spindle-shaped cells arranged in characteristic whirling and swirling patterns.
Stains & Differential (15:44): The tumor is strongly positive for CD34 and Epithelial Membrane Antigen (EMA), but negative for neural markers (Sox10, S100). The morphology and CD34 positivity put it in the differential for Dermatofibrosarcoma Protuberans (DFSP).
Takeaway: This is a benign peripheral nerve sheath tumor of perineurial cells. The swirling morphology and CD34/EMA positivity are diagnostic. Simple excision is curative.
Details: Erythematous plaque on sun-damaged skin (dorsal forearm) of a 60-year-old woman. Pathology shows numerous ectatic, thin-walled vascular channels embedded within abundant solar elastosis. The growth is plaque-like ("east to west") and non-infiltrative.
Takeaway: A benign vascular lesion associated with sun damage. The non-atypical endothelial lining and non-infiltrative pattern are essential for distinguishing it from early angiosarcoma.
28:00 Case 5: Acrodermatitis Enteropathica (Zinc Deficiency)
Details: Erythematous plaques on the face and groin. Histology presents the classic triad of psoriasiform epidermal hyperplasia, along with pallor and ballooning of keratinocytes in the superficial spinous layer. Confirmed zinc deficiency.
Takeaway: This histology is characteristic of nutritional deficiency (zinc or other minerals). The differential includes Necrolytic Migratory Erythema (associated with glucagonoma syndrome).
31:36 Case 6: Coma Blister (Pressure-Induced Ischemia)
Details: Sub-epidermal blister/cleft due to pressure-induced acute ischemia (patient incapacitated for a long period). The epidermis is ghosted (necrotic with dissolving nuclei but intact cytoplasm) and lifts away from the dermis.
Key Clue (37:06): Necrosis of the eccrine coils (secretory part) while the eccrine ducts remain intact, a highly sensitive marker for acute ischemia/hypoxia.
Takeaway: The finding of acute epidermal and eccrine coil necrosis requires investigating the underlying cause of ischemia (e.g., pressure, coagulopathy, infectious angio-invasion).
39:03 Case 7: Chemotherapy Effects (Thrombocytopenia/Drug Excretion)
Details: Petechial eruption in a chemotherapy patient. Hemorrhage in the superficial dermis is attributed to chemotherapy-induced thrombocytopenia. The epidermis shows atypia/dysmaturation.
Syringometaplasia (43:40): The eccrine ducts exhibit squamous syringometaplasia (enlargement and transformation into squamoid keratinocytes) due to chemical irritation from chemotherapy drugs being excreted in the sweat.
Details: Excision specimens from the groin demonstrating the variable pathology of HS: ruptured follicular cysts, abscess formation, inflammation, and extensive granulation tissue. One variant shows neutrophils filling the apocrine glands (apocrinitis).
Takeaway: HS pathology is often non-specific, resembling ruptured cysts or abscesses. The diagnosis is primarily clinical, based on chronic, bilateral involvement in intertriginous areas (axilla, groin).