[Retroperitoneal lymphangiomyomatosis. Immunohistochemical and ultrastructural study of a case].

A case of retroperitoneal lymphangiomyomatosis occurring in a 34-year-old woman is reported. Alpha-smooth muscle actin and desmin were localized in the proliferating cells. Electron microscopy showed the presence of many thin perinuclear myofilaments with dense bodies. The differential diagnosis with leiomyosarcoma has been taken into consideration.