Adenocarcinoma in situ arising in vulvar papillary hidradenoma: report of 2 cases.

Adenocarcinoma in situ rarely occurs in vulvar papillary hidradenoma. We encountered 2 cases of adenocarcinoma in situ arising in a papillary hidradenoma of the vulva. Both patients were asymptomatic women, aged 83 and 92 years, who presented with nodules (1.0 and 2.0 cm) on the vulva. Macroscopically, the lesions seemed tan-pink, fleshy, and well circumscribed. One tumor ulcerated the overlying epidermis. On microscopic examination, the tumors showed focal features of benign hidradenoma at the periphery with transitions into areas of increasing cytologic atypia that fulfilled criteria for adenocarcinoma in situ similar to that seen in the breast. One tumor showed a predominant cribriform pattern with moderate atypia and many mitoses; the other showed a mixture of cribriform and micropapillary patterns, mild atypia, and fewer mitotic figures. There was no evidence of destructive invasion or desmoplasia in either tumor. Both lesions show areas strongly immunoreactive for mammaglobin and gross cystic disease fluid protein 15 as well as estrogen and progesterone receptor protein in 1 case. There was no evidence of benign ectopic breast tissue within or adjacent to the neoplasms. Both patients underwent local excision with no evidence of tumor recurrence at 15 and 32 months of follow-up. The fact that these tumors displayed morphologic and immunohistochemical features that resembled ductal carcinoma in situ of the breast demonstrates the close homology between papillary hidradenoma and breast epithelium. In the absence of invasion, our experience suggests that these tumors can be cured by local excision.