Superficial angiomyxoma (cutaneous myxoma): a clinicopathologic study of 17 cases arising in the genital region.

Seventeen cases of superficial angiomyxoma (cutaneous myxoma) of the genital region are reported. Thirteen patients were female (age range: 15-33 years; mean: 21 years) and four were male (age range: 18-55 years; mean: 39 years). The sites of involvement in females were the labium majus or labium, not otherwise specified (n = 6), vulva (n = 4), groin (n = 2), and mons pubis (n = 1). All lesions in male patients involved the scrotum. The tumors were present from 2 months to 4 years before resection and ranged from 0.9 to 6 centimeters in maximal dimension; 10 tumors were 3 centimeters or less in size. The predominant reason for seeking medical attention was a slow growing painless mass. All lesions were locally excised. Follow-up was obtained for 9 patients with a mean and median follow-up interval of 135 and 95 months, respectively. A recurrence developed in three patients at 8 months, 7 years 11 months, and 20 years. No patient has been shown to have Carney's complex. The tumors were immunoreactive for vimentin (11/11), CD34 (11/11), muscle-specific actin (8/12), smooth muscle actin (9/11), S100 protein (5/13), and Factor XIIIa (5/9). No immunoreactivity was present for desmin (DE-R- 11), glial fibrillary acidic protein, estrogen receptor or progesterone receptor. Superficial angiomyxomas are probably derived from fibroblast-like cells capable of antigen modulation.