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.