Case Presentation: 61-year-old male with a known history of alcohol and tobacco abuse was admitted with 3 months history of headache, confusion, unsteady balance and unintentional weight loss. Laboratory tests included normal chemistry panel, complete blood count and negative hepatitis and HIV serology. Brain imaging showed 3 lesions in the right cerebral convexity with surrounding edema and mass effect. Thoracic imaging was notable for a spiculated, centrally necrotic mass in the right infrahilar region and an irregular nodule. A positron emission tomography (PET) scan confirmed increased fluorine-18-deoxyglucose (FDG) activity in the lung nodule and sub-carinal lymph nodes. There was concern for primary lung malignancy with metastasis to lymph nodes and brain and a bronchoscopy with broncho-alveolar lavage (BAL) was performed. The cultures grew respiratory flora. The pathology revealed no evidence of malignancy or atypia. Concerned about inadequate biopsy samples, bronchoscopy was repeated. While awaiting the results of the second biopsy, the original biopsy was re-examined and found to have branching, partially acid-fast bacilli on the modified acid fast, Fite and Giemsa stains. Matrix-Assisted Laser Desorption Ionization mass spectrometry confirmed the organism as Nocardia wallacei. A sample of the brain lesions and pathology on the second bronchoscopy also revealed Nocardia wallacei. Empirically, intravenous Trimethoprim-Sulfamethoxazole with Imipenem was initiated before switching to Ceftriaxone once organism sensitivities were available. Patient was re-admitted for cerebral salt wasting and increased brain abscess size necessitating drainage. He has since been lost to follow up.
Discussion: The incidence of Nocardia is under-reported since nocardiosis is not a reportable disease and it is difficult to diagnose. Individuals at risk are typically immonucompromised; most commonly from HIV, transplant or malignancy.This case is unique in that, aside from heavy alcohol abuse, the patient was not immunocompromised. In a study of patients with pulmonary Nocardia, alcoholism was found to be a risk factor in only 6.5% of patients; however, it was associated with dissemination to the central nervous system.
This case also highlights the importance of avoiding anchoring biases. Malignancy was originally thought to be the cause due to radiological readings. In a study about nocardiosis in Switzerland, pulmonary tuberculosis was the most common unconfirmed initial diagnosis. Others were malignancy and chronic fungal infections.
Conclusions: Disseminated Nocardia is most commonly seen in immunocompromised patients, but should also be considered in patients with chronic medical illnesses. Anchoring to other unconfirmed diagnoses often delays time of diagnosis and may lead to adverse outcomes.