Unusual Presentation of Hidradenoma Papilliferum on Terminal Phalanx - A Rare Case Report

Hidradenoma papilliferum(HP) is a benign tumor of apocrine differentiation. It presents as dermal papulonodular lesion and usually occurs in women in the age range from 30-80 years. The common sites involved are on the labia majora or in the perineal or perianal region. The tumor is covered by normal skin and measures only a few millimeters in diameter. Malignant changes have also been reported in hidradenoma papilliferum in rare cases as aggressive adenosquamous or squamous cell carcinoma. Differential diagnosis may include tumors with same apocrine differentiation namely syringocystadenoma papilliferum and tubular apocrine adenoma. The diagnosis depends predominantly on the histomorphology of the lesion.