Multiple superficial basal cell carcinomas (basalomatosis) following cobalt irradiation

Basalomatosis is an uncommon skin condition characterized by the occurrence of multiple basal cell carcinomas. Many cases reported in the literature have been attributed to arsenic treatment in psoriasis patients. We report a patient with basalomatosis caused by cobalt-60 (60Co) irradiation. A 55-year-old farmer developed 43 basal cell carcinomas 20 years after treatment of an immunoblastoma with 60Co irradiation. All the tumours were located within the radiation fields. Other possible causes of basalomatosis, such as arsenic intoxication and basal cell naevus syndrome, were excluded. The patient's multiple superficial basal cell carcinomas probably represent a late adverse effect of the 60Co irradiation.