Pilomatrixoma in a Maltese Dog

A 12-year-old female Maltese dog brought to a local veterinary clinic with two nodules in the subcutis of left shoulder. The nodules were grown gradually from 2 years ago. The nodules were removed surgically under anesthesia and examined histopathologically. They were 15×26 mm in diameter (oval form) and 12×15 mm in diameter (round form), respectively. Histopathologically, the lesions consisted of multi-layered basaloid cells in the peripheral of the mass and ghost cells in the central region. Typical findings of these two nodules were gradually keratinized basaloid cell toward central area result in forming anuclear ghost cells. These microscopic features of cutaneous nodules were diagnosed as pilomatrixoma and the identified findings were similar to fully developed stage of human pilomatrixoma. This report may assist in the categorizing of canine pilomatrixoma using histopathological features.