Anetodermic pilomatricoma: clinical, histopathologic, and sonographic findings.

Pilomatricoma is a benign cutaneous tumor originatingfrom hair matrix cells. Anetodermic changes inthe skin overlying pilomatricomas are sometimesreported, although their precise mechanisms remainunknown. We present an unusual case of anetodermicpilomatricoma on the upper extremity of a 17-yearoldboy and report its clinical, histopathologic, andsonographic findings.

[Anetodermic pilomatricoma. Uncommon variant of a common childhood adnexal tumor]. / Anetodermisches Pilomatrikom. Seltene Variante eines häufigen Adnextumors im Kindesalter.

The anetodermic ("bullous") subtype is a rare variant of pilomatricoma which we diagnosed in 2 girls who were 9 and 10 years old. The tumors presented as 3 × 2 and 1.5 × 1.5 cm red dome-shaped nodules with a slightly wrinkled surface on the upper back and on the pretibial region, respectively. Both were superficially soft, but then firm as one palpated deeper. Histology showed an edematous, well-vascularized dermis resembling granulation tissue overlying a deep otherwise typical pilomatricoma. Clinical and histological characteristics of the anetodermic subtype are discussed on the basis of previously published cases.