GENITAL ANGIOMYOFIBROBLASTOMA - COMPARISON WITH AGGRESSIVE ANGIOMYXOMA AND OTHER MYXOID NEOPLASMS OF SKIN AND SOFT-TISSUE

Angiomyofibroblastoma (AMFB) of the genital region is a relatively rec ently described tumor of the superficial soft tissues with a marked pr eference for female patients. Three cases of AMFB were reviewed, two o f which involved adult men. To further elucidate the pathologic featur es of AMFB, these three cases were compared with 10 cases of aggressiv e angiomyxoma (AA), a salient diagnostic alternative, and 28 cases of other myxoid tumors that may show morphologic similarities to these ne oplasms. Conventional histologic and immunohistochemical features of A MFBs were compared with those of AA, myxoid leiomyoma, myxoid leiomyos arcoma, myxoid liposarcoma, myxoid malignant fibrous histiocytoma, myx oid neurofibroma, and myxoid malignant peripheral nerve sheath tumor. The ultrastructure of two of the three AMFBs also was analyzed. Genita l AMFBs were circumscribed, partially myxoid proliferations that demon strated considerable variation in cellular density. Neoplastic element s were bland cytologically and showed both fusiform and epithelioid pr ofiles, with a tendency to concentrate around intralesional blood vess els. Mitotic activity and necrosis were absent, and the vessels assume d an arborizing configuration and were venule or capillary sized. In c ontrast, all other tumor types evaluated were infiltrative, cytologica lly atypical, or both. All AMFBs showed immunoreactivity for vimentin, desmin, actin, and estrogen receptor protein. These results were shar ed by most examples of AA and smooth muscle tumors as well, but were n ot seen in any other neoplasms in this study. Electron microscopic fin dings in cases of AMFB supported the presence of myofibroblastic diffe rentiation in the tumor cells. These results indicate that conventiona l morphologic analysis is paramount in the recognition of genital AMFB but that immunohistology may be helpful in a limited context in exclu ding other differential diagnoses. They also support the conclusion th at AMFB, AA, and superficial smooth muscle tumors have similar morphot ypes and immunohistologic attributes regardless of their origin in men or women.