Proliferating Pilar (Tricholemmal) Cyst/Tumor
Multicystic squamous neoplasm composed of mature keratinocytes lining keratin-filled spaces Etiology/Pathogenesis • Postulated that most cases arise in preexisting pilar (tricholemmal) cyst; may be related to chronic inflammation or trauma Clinical…
Papillary Endothelial Hyperplasia (Masson Tumor)
PEH lacks nuclear atypia, tumor cell necrosis, and mitotic activity present in angiosarcoma • Hemangioma • PEH-like changes may occur in hemangiomas complicated by thrombosis • Arteriovenous malformation (AVM) PEH-like changes may occur…
Lymphangioma and Superficial Lymphangioma
Large, Deep LymphangiomaClinical photograph shows a large, deep lymphangioma (cystic hygroma) on the lateral neck of a child. Superficial LymphangiomaThis example of a superficial lymphangioma shows widely dilated spaces in…
Cutaneous Mixed Tumor (Chondroid Syringoma)
Chondroid Syringoma/Cutaneous Mixed Tumor Low MagnificationLow magnification shows a well-circumscribed tumor composed of epithelial islands with easily identifiable glandular/ductal structures embedded in a myxoid and hyaline stroma. Cutaneous Mixed Tumor…
Apocrine Tubular Adenoma
Tumors in anogenital area may truly represent adenoma of anogenital mammary-like glands Tumors in eyelid should be distinguished from endocrine mucin-producing sweat gland carcinoma • F > M (2:1) • Adult patients…
Microcystic Adnexal Carcinoma
MAC on CheekClinical photograph of microcystic adnexal carcinoma (MAC) on the cheek of a middle-aged woman shows a flesh-colored papular to plaque-like lesion. MAC at Low MagnificationScanning magnification of a…
Papillary Intralymphatic Angioendothelioma (Dabska Tumor)
Most cases occur in adults but some occur in children May show significant overlap with Dabska tumor, with prominent papillary structures • Composite hemangioendothelioma Composed of at least 2 distinct HE…
Fibrofolliculoma and Trichodiscoma
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…
Superficial Low-Grade Fibromyxoid Sarcoma
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…
