Actinomycosis. A cause of pulmonary and mediastinal mass lesions in children.

Two patients with intrathoracic actinomycosis were examined. One child was asymptomatic and had a slowly expanding lesion in the left upper lobe. The other child had a chronic illness with back pain, weight loss, amenorrhea, and a posterior mediastinal mass. Establishing the cause of these lesions and making the distinction between a neoplastic process and infection were particularly difficult in both cases. Intrathoracic actinomycosis should be considered in the differential diagnosis of pulmonary and mediastinal mass lesions.