Se presenta un caso de actinomicosis de partes blandas, en muslo izquierdo, con lesión pulmonar asociada, que sólo se llegó a diagnóstico tras biopsia muscular, sin haber conseguido diagnosticar al paciente tras la realización de broncoscopia pulmonar y haber realizado cepillado bronquial para citologia y cultivo. El tratamiento con penicilina hizo regresar las lesiones pulmonares y musculares, por lo que se llegó al diagnóstico de actinomicosis de partes blandas asociadas a lesión pulmonar.
A case of actinomycosis of the soft tissues of the left thigh with an associated pulmonary lesion is presented. A diagnosis could not be made after a pulmonary bronchoscopy with bronchial brushing and cytological examination and culture were done and was only established after a muscle biopsy was obtained. The pulmonary and muscle lesions disappeared after penicillin treatment and a diagnosis of actinomycosis of soft tissues associated with a pulmonary lesion was made.