Malignant lymphoma and malignant angioendotheliomatosis: one disease.

A patient was diagnosed as having angioendotheliomatosis proliferans systemisata (APS) based on characteristic clinical and histologic features. A few days later, malignant lymphoma involving the gut was discovered. Immunohistochemical and electronmicroscopic studies confirmed the nonendothelial and lymphoid nature of intravascular tumor cells. This is the sixth case in which malignant lymphoma has been shown to involve the vessels of the skin (and probably of other organs) in a pattern identical to that seen in APS.