CASE PRESENTATION: A 68 year-old Caucasian gentleman presented to our clinic with a chronic cough associated with copious phlegm production. He denied fevers, weight loss, night sweats or shortness of breath. He had history of advanced metastatic prostate cancer, previously treated with multiple cycles of radiation and chemotherapy. He was maintained on antiandrogen therapy and recently started on steroids. He had normal vital signs with an oxygen saturation of 94% on room air. His physical exam revealed coarse breath sounds bilaterally. A chest x-ray showed no active pneumonia. A review of his past chest CTs’ showed interval development of a ground-glass infiltrate in the right upper lung lobe with progression to a more confluent scarring and nodular pattern over the last 6 months (Figure 1, 2). A CT-guided biopsy showed numerous histiocytes with central necrosis, consistent with a caseating granuloma. A serum quantiferon was negative. Serology for blastomycosis, coccidiodomycosis, cocryptococcus and histoplasmosis were also negative. His sputum was positive for acid fast bacillus (AFB). Subsequent cultures were reported positive for M. asiaticum, but negative for M. tuberculosis and M. avium intercellulare. The isolated bacterium was resistant to ethambutol, rifampicin and ciprofloxacin, but sensitive to linezolid, rifabutin, streptomycin, moxifloxacin, and clarithromycin. In light of his comorbidities and in the absence of systemic symptoms, our infectious disease colleagues decided not to pursue treatment.