The collective term histiocytoid hemangioma encompasses a spectrum of diseases that share a histologic features characterized by distinctive histiocytoid endothelial cells. Several incompletely defined cutaneous and extracutaneous vascular tumors, including atypical pyogenic granuloma, pseudopyogenic granuloma, papular angioplasia, angiolymphoid hyperplasia with eosinophilia, Kimura's disease, and inflammatory arteriovenous hemangioma, have been included in this group. We describe a 31-year-old Mexican-American man with multiple histiocytoid hemangiomas involving skin, subcutaneous tissue, and bone limited to the left arm and hand. Examination of skin and bone lesion biopsy specimens showed a proliferation of histiocytoid endothelial cells with intracytoplasmic vacuoles and associated vascular lumen formation. Ultrastructural and immunoperoxidase studies supported endothelial cell differentiation. Radiation therapy resulted in significant clinical improvement. Current concepts regarding the clinical and pathologic features of this disease spectrum also are discussed.