A papillary hidradenoma, also hidradenoma papilliferum, is a sharply circumscribed nodule or benign tumor of the apocrine gland usually found on the labia majora or the interlabial folds. It is benign tissue (not cancerous) but is often confused clinically with carcinoma of the vulva because of its tendency to ulcerate.Intermed. mag.Very high mag. A papillary hidradenoma, also hidradenoma papilliferum, is a sharply circumscribed nodule or benign tumor of the apocrine gland usually found on the labia majora or the interlabial folds. It is benign tissue (not cancerous) but is often confused clinically with carcinoma of the vulva because of its tendency to ulcerate.