Spindle cell hemangioendothelioma is a rare vascular tumor which is presented with subcutaneous nodules and follows a benign indolent course but has a recurrent tendency, and is histologically resembling a cavernous hemangioma and Kaposi's sarcoma. We present a case of spindle cell hemangioendothelioma possessing clinical aggressiveness with painful bony erosion, histologic pleomorphism and mitoses. A 20-year-old man presented with a recurrent painful mass on the left ankle. The mass was dark brown and firm with irregular margins and measured 1.5 cm in diameter, which affected and eroded the underlying medial malleolus of the left tibia. Microscopically, the tumor was composed of cavernous endothelial-lined blood spaces and spindle cellular areas mimicking Kaposi's sarcoma. The spindle cells intermingled with plump epithelioid cells and showed a moderate degree of pleomorphism with occasional mitoses. Immunohistochemically, the spindle cells were focally positive for factor VIII-associated antigen and vimentin, and negative for S-100 protein, desmin, and epithelial membrane antigen.
Adult ; Bone and Bones/pathology ; Case Report ; Hemangioendothelioma/*diagnosis/pathology/ultrastructure ; Human ; Male ; Microscopy, Electron ; Soft Tissue Neoplasms/*diagnosis/pathology/ultrastructure

OBJECTIVETo study the clinicopathologic features, differential diagnosis and pathogenesis of sclerosing angiomatoid nodular transformation of spleen.

METHODSTen cases of sclerosing angiomatoid nodular transformation of spleen were retrieved from the archival file. Histochemical and immunohistochemical (EnVision method) studies were performed. Ultrastructural findings were also available in one of them.

RESULTSSclerosing angiomatoid nodular transformation was characterized by micronodular appearance of vascular spaces lined by plump endothelial cells with interspersed ovoid spindle cells. Immunohistochemical study showed that the endothelial cells of vessels in the angiomatoid nodules had various expressions of immunologic phenotypes and could be mainly classified into 3 types: CD34(+)/CD31(+)/CD8⁻ endothelial cells of the capillaries, CD8(+)/CD31(+)/CD34⁻ lining cells of the sinusoids and CD31(+)/CD8⁻/CD34⁻ endothelial cells of the small veins. Collagen network and dilated lymphatic sinuses were evident under transmission electron microscope.

CONCLUSIONSSclerosing angiomatoid nodular transformation of spleen is a rare benign entity. It may represent a reactive condition and bears some relationship with splenic angioma. It needs to be distinguished from borderline or malignant vascular tumors of spleen.

Adult ; Antigens, CD34 ; metabolism ; CD8 Antigens ; metabolism ; Diagnosis, Differential ; Female ; Hemangioendothelioma ; metabolism ; pathology ; Hemangiosarcoma ; metabolism ; pathology ; Histiocytoma, Benign Fibrous ; metabolism ; pathology ; surgery ; ultrastructure ; Humans ; Male ; Microscopy, Electron ; Middle Aged ; Platelet Endothelial Cell Adhesion Molecule-1 ; metabolism ; Splenic Neoplasms ; metabolism ; pathology ; surgery ; ultrastructure