[Pilomatricoma-a clinicopathological analysis of 22 cases, including 2 cases of bullous pilomatricoma].

Twenty-two patients with pilomatricoma seen from January 1986 to October 1990 were analyzed retrospectively. The incidence of pilomatricoma in our dermatopathologic material is 1 in every 50 cases of skin tumors. Male to female ratio is 1:2. Half of the tumors appeared before the age of 30. Most of the tumors develop in the head, neck and upper extremities. Two pilomatricomas appeared with overlying bullae. Pathologically, multiple dilated lymphatics in the dermis were found above the typical nests of shadow cells and basophilic cells. Clues to clinical diagnosis are summarized below. The stony hard, deep-seated tumor, covered by normal skin, is usually located in the upper extremity. Tumors with blue-red discoloration, firm or elastic, frequently found in eyelid and face, are located more superficially, clinically they should be differentiated from epidermal cysts. Erythematous protruding tumors occur in the scalp or face. Bullous pilomatricoma is characteristically manifested as a flaccid, thick-walled bulla with an underlying palpable hard nodule, usually seen in the shoulder, upper arm or the head.