Anetodermic variant of a periorbital pilomatricoma

Pilomatricoma usually presents as a solitary hard nodule located deep in the dermis. However, a variant termed anetodermic is often seen in the elderly. Instead of a hard nodule, a rapidly growing bullous lesion is seen. The authors report a 60-year-old man who presented with an erythematous bullous lesion at the left medial canthus. The lesion started as a small 3-mm papule and grew significantly to a 12-mm lesion in 5 weeks. Histopathologically, the tumor was composed of basophilic and keratinized shadow cells typical of pilomatricoma. Anetodermic changes could also be seen, represented by intralesional hemorrhage, dilated blood and lymphatic vessels, and disruption of dermal collagen fibers. The anetodermic variant of pilomatricoma was described in 1943 and accounts for only 2% of cases. Compression of vessels by the neoplastic process and peritumoral inflammatory infiltration are the proposed pathogenic mechanisms underlying the atypical findings.