An unusual cause of thoracic mass.

A previously well 10 year old boy presented with scoliosis, a mass in the chest wall, and a pleural effusion. Chest radiography showed the triad of chronic consolidation, pleural effusion, and rib periostitis. Investigations confirmed thoracic actinomycosis. Tissue spread was evaluated by computed tomography. It was successfully treated with benzylpenicillin, which was later replaced by clindamycin.