Early Stage of Pilomatricoma with an Empty Cyst Cavity and Unusual Clinical Appearance.

We present an unusual case of cystic pilomatricoma. A 13-year-old Japanese boy was referred to our department for evaluation of a 10-day history of a small reddish nodule on his right cheek. Histopathological examination showed a well-circumscribed cystic structure showing a central empty cavity in the dermis. The wall of the cyst was composed of basophilic cells. Inner layers of the wall were covered with flattened epithelial cells having trichohyalin granules. Based on these findings, a diagnosis of cystic pilomatricoma was made. To our knowledge, there has been no report of cystic pilomatricoma with an empty cavity. Dermatologists should be aware of pilomatricoma in the early stage showing a central empty cavity.