High risk of renal cell carcinoma Also, pulmonary cysts and pneumothoraces Clinical Issues • Typically present as multiple small papule(s) on face Microscopic • FF shows proliferation of thin, anastomosing epithelial cords…
Histologically and genetically identical to conventional deep LGFMS Clinical Issues • Appear to represent 10-20% of reported cases of LGFMS • Often adults (typically 3rd-4th decade), but wide range Up to 1/3…
Solitary, dome-shaped, flesh-colored papules on nose or central face • Adenoma sebaceum: Angiofibromas associated with tuberous sclerosis Grouped papules or nodules with butterfly distribution on central face • May clinically mimic basal…
Sometimes with true glandular formation • Round vesicular nuclei with prominent nucleoli • Abundant clear cytoplasm May contain intracytoplasmic melanin • Absence of intercellular bridges • Paget cells often extend to adnexal structures • Flattened…
Haphazard arrangement Thin fascicles rather than solid growth pattern No atypia No mitoses No necrosis Immunohistochemistry (+) for muscle markers Top Differential Diagnoses • Cutaneous leiomyoma (pilar leiomyoma) Occurs in adults…
Also associated with organ transplantation, systemic steroids, and leukemia Clinical Issues • Occurs in both adults and children • Can involve any cutaneous site; uncommonly involves mucosal sites, deep soft tissues • Typically…
Located centrally within lobules • Basaloid/germinative cells at periphery of lobules • Cytologic atypia not prominent • Presence of mitotic figure in germinative layer does not indicate malignant potential Ancillary Tests • Sebocytes express…
Apocrine differentiation is usually seen Often with decapitation secretion • Outer layer of cuboidal myoepithelial cells • Variable degree of mitotic index Top Differential Diagnoses • Syringocystadenoma papilliferum (SCP) Similar histologic features, indicating…
Deep subcutaneous/fascial/muscular extension, necrosis, &/or lymphovascular invasion Shows no identifiable line of differentiation (i.e., diagnosis of exclusion) • Synonyms: Superficial malignant fibrous histiocytoma, undifferentiated pleomorphic sarcoma of skin Clinical Issues • Older…
Presence of keratocysts allows for distinction (absent in eccrine carcinoma) • Adenoid cystic carcinoma Cribriform architecture allows distinction (generally absent in eccrine carcinoma) • Infiltrative basal cell carcinoma Lacks true lumen formation…
