Amyloidoma Cyril Fisher, MD, DSc, FRCPath Key Facts Terminology Solitary localized tumor-like deposit of amyloid in absence of systemic amyloidosis Macroscopic Features Pale waxy cut surface Microscopic Pathology Amorphous acellular…

PEComa Elizabeth A. Montgomery, MD Key Facts Terminology PEComa is abbreviation for neoplasms with perivascular epithelioid cell differentiation Mesenchymal neoplasms composed of distinctive perivascular epithelioid cells Includes angiomyolipoma (AML), clear…

Clear Cell Sarcoma Elizabeth A. Montgomery, MD Key Facts Terminology Sarcoma showing melanocytic differentiation Malignant melanoma of soft parts Clinical Issues Young adults (3rd or 4th decade) Usually affects extremities…

Epithelioid Sarcoma Cyril Fisher, MD, DSc, FRCPath Key Facts Terminology Malignant mesenchymal tumor resembling carcinoma or granuloma Shows predominantly epithelial but also mesenchymal differentiation Occurs in classical and proximal aggressive…

Extrarenal Rhabdoid Tumor Cyril Fisher, MD, DSc, FRCPath Key Facts Terminology Malignant neoplasm of polygonal cells with characteristic large cytoplasmic inclusion and eccentric large nucleus Requires exclusion of specific tumor…

Alveolar Soft Part Sarcoma Julie C. Fanburg-Smith, MD Aaron Auerbach, MD Key Facts Terminology Alveolar soft part sarcoma (ASPS) Malignant soft tissue tumor of uncertain phenotype that mainly affects young…

Synovial Sarcoma Cyril Fisher, MD, DSc, FRCPath Key Facts Terminology Name is historical accident, as tumor does not arise from or differentiate toward synovium Mesenchymal spindle cell tumor with variable…

Phosphaturic Mesenchymal Tumor Elizabeth A. Montgomery, MD Key Facts Terminology Synonym: Osteomalacia-associated mesenchymal tumor Definition: Rare distinctive mesenchymal neoplasm associated with oncogenic osteomalacia Clinical Issues Complete excision cures intractable oncogenic…

Ossifying Fibromyxoid Tumor Cyril Fisher, MD, DSc, FRCPath Key Facts Terminology Encapsulated tumor of small polygonal cells in fibromyxoid stroma with metaplastic ossification Majority benign Occasional atypical or malignant variants…

Angiomatoid Fibrous Histiocytoma Khin Thway, BSc, MBBS, FRCPath Key Facts Terminology Rare neoplasm of intermediate biologic potential Most often arises in extremities of children and young adults Histologically often confused…