Pilomatricoma of the testicle. An ossifying testicular tumor with hair matrix differentiation.

Teratomas of the testis account for 4% of all testicular tumors. Monodermal variants (eg, epidermal inclusion cysts) account for less than 1% of all these tumors. To our knowledge, we are reporting the first case of pilomatricoma of the testis, a monodermal teratomatous tumor of follicular differentiation, with secondary heterotopic ossification. The differential diagnosis of the characteristic "shadow" cells is discussed, and the significant literature on both benign and malignant ossifying lesions of the testis is reviewed.