Abstract

In spite of the histologic overlap, the relationship between angioleiomyoma and myopericytoma has not yet been fully evaluated. One hundred thirty lesions originally diagnosed as angioleiomyoma and 4 tumors identified as myopericytoma were reassessed both histologically and immunohistochemically. One hundred twenty-two tumors were thus reclassified as angioleiomyoma (74 solid, 37 venous, and 11 cavernous types) and 12 as myopericytoma based on the predominant histologic pattern. In 1 patient, 1 myopericytoma and 1 venous-type angioleiomyoma were synchronously present. The perivascular concentric arrangement of cells, which is a salient feature of myopericytoma, was also focally recognized in 19 angioleiomyomas (12 venous, 4 solid, and 3 cavernous types). An angioleiomyoma-like fascicular pattern of elongated myoid cells was partially present in 7 myopericytomas, 4 of which resembled the feature of the cavernous subtype and 3 the venous one. Immunohistochemically, most tumor cells of all cases of both angioleiomyomas and myopericytomas were diffusely positive for actins (alpha-smooth muscle actin and HHF35) and calponin, and all cases, except for 1 myopericytoma, were also diffusely or focally positive for h-caldesmon. Desmin was diffusely positive in 75.7% of solid-type angioleiomyomas, 51.4% of venous type, and 18% of cavernous type, whereas most of the myopericytomas were negative for desmin, even though desmin-positive cells were only partially seen in 3 myopericytomas. The concentric structures of myoid cells in angioleiomyomas were, however, consistently negative for desmin. Our data further support the close kinship between angioleiomyoma and myopericytoma that has been recently suggested.