Primary vascular tumors of lymph nodes other than Kaposi's sarcoma. Analysis of 39 cases and delineation of two new entities.

Primary vascular tumors of lymph nodes other than Kaposi's sarcoma are very rare, as attested to by only a handful of case reports in the literature. Based on an analysis of 39 such cases, we could distinguish five major groups. Hemangiomas of capillary/cavernous, lobular capillary, and cellular types were composed of compact aggregates of blood-filled vessels, variable in size, that replaced the nodal architecture partly or almost completely; some appeared to have originated in the hilum or medulla. These hemangiomas either represented incidental findings in lymph nodes or were seen with solitary lymph node enlargement; the evolution was benign with no recurrence. A distinctive benign lesion occurring exclusively in inguinal lymph nodes, which we propose designating "angiomyomatous hamartoma," showed replacement of the nodal parenchyma by smooth muscle cells and fibrous tissue, in continuity with exuberant proliferation of muscular vessels in the hilum. Epithelioid vascular tumors, characterized by plump endothelial cells with dense eosinophilic cytoplasm and numerous vacuoles, exhibited a range of differentiation, from hemangioma with well-formed vascular channels (with or without tissue eosinophilia) to hemangioendotheliomas composed predominantly of cords and sheets of tumor cells lying in a hyaline-myxoid matrix. Epithelioid hemangioendothelioma was particularly likely to be mistaken for metastatic carcinoma, and local recurrence could occur. A variant, the spindle and epithelioid hemangioendothelioma, was characterized by the presence of an additional component of spindle cells. Another tumor we found, polymorphous hemangioendothelioma, is a previously uncharacterized borderline malignant vascular tumor exhibiting solid, primitive vascular and angiomatous patterns and relatively bland cytologic features. Lymphangiomas of lymph nodes usually showed simultaneous multifocal and extra-nodal involvement and were characterized by cystic endothelium-lined spaces filled predominantly with lymph fluid. It is important to recognize these primary vascular tumors of lymph nodes to avoid mistaking them for a variety of benign vasoproliferative lesions, Kaposi's sarcoma, angiosarcoma, and metastatic cancer.