Acquired benign and "borderline" vascular lesions.

In recent years, the classification of vascular lesions has been expanded and modified with the addition of several newly described entities, the redefinition of others, the recognition of lesions of borderline biologic behavior, and the need to avoid misdiagnosis with early Kaposi's sarcoma. This review clarifies the nomenclature, updates information on previously known lesions, and summarizes data on several recently discovered, lesser-known entities such as glomeruloid hemangioma, microvenular hemangioma, and multinucleate cell angiohistiocytoma. Clinicopathologic features and differential diagnosis are emphasized.