A Case of Disseminated Nocardiosis due to Nocardia otitidiscaviarum With Pulmonary Infection and a Thyroid Abscess.

A 64-year-old man without relevant medical history was admitted with appetite loss and dyspnea. Chest CT showed a 5 cm right upper lobe mass and diffuse granular shadows throughout the lungs. Initial treatment targeted suspected pneumonia with lung cancer, but cultures from admission blood and sputum samples revealed Nocardia on day three, leading to oral trimethoprim-sulfamethoxazole. Despite therapy, his respiratory condition worsened, and he died on the 10th day of hospitalization. Autopsy demonstrated squamous cell carcinoma in the right upper lobe. The diffuse pulmonary nodules showed neutrophil infiltration and focal necrosis, consistent with necrotizing pneumonia, and similar lesions were found in the thyroid. The cultured organism was later identified as Nocardia otitidiscaviarum, and the cause of death was determined to be disseminated nocardiosis. Nocardia infection is an infrequent disease that can have a fatal course; therefore, clinicians must consider the diagnosis early, perform rapid bacteriological testing and initiate timely and appropriate treatment.