Angioleiomyoma: a clinicopathologic and immunohistochemical reappraisal with special reference to the correlation with myopericytoma.

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.