This review discusses multiple cutaneous malignancies that can present on the perineum. Although all of these neoplasms are uncommon, a focus will be on the more common neoplasms including extramammary Paget disease, basal cell carcinoma, squamous cell carcinoma, and melanoma. Other more rare entities discussed are superficial leiomyosarcoma, giant solitary trichoepithelioma, and cutaneous endometriosis.

We present a 10-week-old girl with myositis ossificans circumscripta (MO) of the neck secondary to nonaccidental trauma. This condition is rarely seen in infants; furthermore, the majority of MO lesions develop in the extremities rather than the head and neck region. We will detail the US-guided biopsy technique used in our case, in addition to discussing the characteristic imaging and pathological findings of MO to assist in the diagnosis and successful treatment of this condition.