Clinical Photograph of SCCis on ForearmThis is an example of squamous cell carcinoma in situ (SCCis)/Bowen disease presenting as an erythematous plaque on the forearm of an elderly male patient…

 Sebocytes in lobules, rimmed by more than 1 layer of basaloid cells  Often connecting directly to epidermal surface • Ectopic sebaceous glands in other sites (e.g., nipple)  Often connect directly to…

 Must exclude cutaneous involvement in multiple myeloma and plasmacytoid B-cell lymphomas, such as primary cutaneous extranodal marginal zone lymphoma Etiology/Pathogenesis • Cell of origin is immunoglobulin-secreting, heavy-chain class-switched, terminally differentiated B…

 Different clinical features: Multiple cutaneous lesions, may have joint &/or internal organ involvement in multicentric cutaneous reticulohistiocytosis • Juvenile xanthogranuloma • Langerhans cell histiocytosis • Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) Solitary…

 Diffuse growth pattern, not scattered cells of lymphomatoid granulomatosis (LYG)  Not angiocentric, usually no necrosis, and no mixed background infiltrate • Vasculitis  Can show similar histologic features to LYG with inflammation…

 Xanthelasma, eruptive, tuberous, tendinous, planar, plexiform Etiology/Pathogenesis • Associated with hereditary lipoproteinemias and occasionally secondary lipoproteinemias • May also occur in normolipemic patients  Particularly plexiform xanthoma Clinical Issues • Wide age range (children…

 May be difficult to identify, especially if desmoplastic type or heavily inflamed Papular Growth in Pigmented PatchThe marked area , prior to biopsy, shows a papular growth in an ill-defined…

 Usually on extremities • Angiokeratoma of Fordyce  Elderly men  Multiple lesions, often on scrotum • Angiokeratoma of Mibelli  Childhood  Warty lesions over bony prominences of acral locations • Angiokeratoma corporis diffusum  Associated with…

 Pretibial skin also common  Uncommon on face • Benign but up to 50% recur • Rare intraoral, orbital, intradural, and paraspinal cases Microscopic • Multiple lobules with abundant myxoid matrix • Well-defined lobular architecture…

 Associated with low recurrence and metastatic rates Microscopic • Multinodular solid or cystic tumor based in dermis • Solid areas composed of dense collections of cells with focal ductal lumina • Cystic/glandular areas…