Histiocytosis X Eosinophilic granuloma • Defined as clonal proliferation of Langerhans cells Clinical Issues • Newborns and infants usually present with limited skin or bone lesions • Erythematous, crusted, vesiculopustular rash • Common sites…
Often evident at birth Occasionally manifest later in life Different clinical course – Generally stable over time (nevus of Ota and Ito) – Resolution with time (Mongolian spot) Blue to gray macule/patch…
Lower > upper extremities • 2/3 of cases arise in dermal/subcutaneous tissues • Local, often repeated, recurrences in up to 50-60% of cases (unrelated to histologic grade) • Intermediate- and high-grade malignant neoplasms…
Small cells with scant cytoplasm and small hyperchromatic nuclei; typically at periphery of tumor lobules Larger cells with eosinophilic cytoplasm and oval, vesicular nuclei; typically in centers of tumor lobules…
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…
