Pilomatrixoma is a rare and benign hair cell-derived tumor occurring mostly in young adults (usually under the age of 20) and characterized as a 3-30 mm solitary, painless, firm, mobile, deep dermal or subcutaneous tumor, most commonly found in the head, neck or upper extremities. When superficial, the tumors tint the skin blue-red. Multiple pilomatrixomas are seen in myotonic dystrophy, Gardner syndrome, Rubinstein-Taybi syndrome, and Turner syndrome. The disease is pilomatrixoma (MONDO_0007564). Also known as: calcifying Epitherlioma of Malherbe, epithelioma calcificans of Malherbe, pilomatricoma, pilomatricoma, somatic, pilomatrixoma, benign.