Nocardia masquerading as pulmonary malignancy in a patient with adult-onset immunodeficiency on ¹⁸F-FDG PET/CT

A 77-year-old man with a history of left nephrectomy for renal cell carcinoma and partial hepatectomy for cholangiocarcinoma underwent ¹⁸F-FDG PET/CT for assessment of an irregular lung lesion. FDG-PET demonstrated development of an intensely avid spiculated left lower lobe pulmonary lesion and intensely avid left pulmonary hilar nodes, raising suspicion for a malignancy. Eleven days following the PET study, the patient was admitted to hospital with an altered mental state. CT brain revealed diffuse round hyperdensities within the brain parenchyma. Microbiology of the lung lesion was positive for Nocardia Beijingensis and he was subsequently diagnosed with disseminated nocardiosis.