Osteoma Cutis of the Scalp in A Case of Multiple Basal Cell Carcinoma Induced By Radiotherapy

Introduction: multiple osteoma cutis is a rare skin disorder characterized by tiny bone fragments deposition in the skin. it is a benign disease, which occurs as primary or secondary forms. secondary osteoma cutis most commonly appears on the facial acne scars in middleaged women. the exact etiology of this phenomenon is unknown, but it may be induced by osteoblastic metaplasia of mesenchymal elements. case presentation: herein, we report a 70-year-old man with a history of multiple basal cell carcinoma (bcc) of the scalp caused by radiotherapy, who referred to our tumor clinic with multiple skin-colored subcutaneous papules and nodules on his scalp from 2 years ago along with cutaneous side effect changes of radiodermatitis. in the histological examination of lesions with differential diagnosis of bcc, cysts, and adnexal tumors, the diagnosis of osteoma cutis was established without any evidence of bcc. conclusion: osteoma cutis is a rare disorder most commonly affecting the face, but our patient had multiple lesions of the scalp. the inflammatory changes of radiodermatitis may be the principal cause of this change.