Selected case from the arkadi M. Rywlin international pathology slide club: Aggressive angiomyxoma, left labial region in a postmenopausal woman.

Club members unanimously agreed with the diagnosis of an unencapsulated 8×2.5×3.6 cm aggressive angiomyxoma, which was invading the voluntary muscles of the pelvic floor beneath the left labium of a female aged 65. The tumor consisted of histologically bland, round, stellate to fusiform cells set in a myxocollagenous matrix with occasional mast cells, a few extravasated red cells, and prominent blood vessels varying from thin-walled capillaries 7 μm in diameter to larger thick-walled vessels >250 μm in diameter. The tumor cells stained positively for estrogen and progesterone receptors, vimentin, and desmin. A stain for the nuclear transcription factor HMGA2, which is emerging as a useful and relatively specific marker for aggressive angiomyxoma, was not performed. The tumor had not recurred 4 years after the surgical excision. One member commented that virtually all lesions diagnosed as aggressive angiomyxomas in superficial locations turn out to be either fibroepithelial stromal polyps or superficial angiomyxomas. None of the club had seen a metastasizing aggressive angiomyxoma nor had they any experience with gonadotropin hormone-releasing and luteinizing hormone-releasing agonists therapy, which have been reported to cause tumor regression.