[Pulmonary actinomycosis. Apropos of a case]

The authors report a case of pseudo-tumoral thoracic actinomycosis with lysis of a rib in a young man who was a heavy smoker and drinker. This observation is an opportunity to review the usual difficulties of diagnosis in patients with this rare disease occurring most often in a patient who is debilitated with important disease in the teeth and gingival margins. The standard treatment is penicillin G, which leads to a cure within one month.