C68-24 Nontuberculous Mycobacterial Infection in a Patient With Metastatic Prostate Cancer

Introduction Nontuberculous mycobacterial (NTM) infection is uncommon and has a prevalence between 1.4 and 13.9 per 100,000 people, though case rates are often higher in patients with compromised immune systems and structural lung disease. Prostate cancer is the most common cancer diagnosis in men in the United States and second most common worldwide, with US men having a 1 in 8 likelihood of receiving a diagnosis in their lifetime. The most common sites of metastasis for prostate cancer are bone and distant lymph nodes, with only 9-16% of metastatic disease presenting as lung metastasis. Most commonly, these are found as solid nodules or lymphangitic spread, with cavitary pulmonary metastases being extremely rare. To our knowledge, there is only one case report of NTM infection involving the same site as metastatic carcinoma in the brain of a patient following renal transplantation. We present here a case of a patient with evidence of prostate cancer at sites of cavitary disease with bronchoalveolar lavage cultures growing NTM. Case Presentation This is an 87-year-old male with a history of metastatic prostate cancer who initially presented with failure to thrive. He underwent CT imaging of his chest which revealed multiple cavitary lung lesions as well as nodules concerning for possible pulmonary metastases vs. infection. Given that he was born in India, he was placed on airborne isolation precautions pending sputum testing for tuberculosis. He subsequently underwent bronchoalveolar lavage for acid-fast stain and culture. These were 2+ smear positive for acid-fast bacilli, and tuberculosis nucleic acid amplification testing was negative for Mycobacterium tuberculosis (NTM speciation pending at time of writing). We were able to acquire prior imaging from other hospital systems, which showed waxing and waning cavitary lesions that pre-dated his prostate cancer diagnosis. The result of a recent prostate-specific membrane antigen positron emission tomography (PSMA PET) CT scan was also found, which showed uptake in the regions of his cavitary lesions. Discussion With cavitary lung disease being a rare presentation of prostate cancer, we hypothesize that the patient had NTM infection for years preceding metastasis of his cancer to the lungs, and this could represent a case of geographic co-involvement of prostate cancer and NTM. Although active infection can sometimes affect its accuracy, PSMA PET remains a highly specific test for prostate cancer metastases. This case expands our current knowledge of the clinical phenotypes of metastatic prostate cancer and NTM infection.