Mai infection simulating metastatic breast cancer

We represent a case of an asymptomatic female who was found to have a mass in the right breast which confirmed an invasive ductal carcinoma by core biopsy. After 3 months of completion of chemo-radiotherapy, the patient remained totally asymptomatic. However, positron emission tomography scan showed four hypermetabolic lesions in the left lung thought to be consistent with metastatic disease. Standard uptake value ranged between 3.86 and 6; the results were consistent with metastatic breast cancer, so wedge resection was performed. Caseating granulomatous inflammation with necrosis was reported. Ultimately culture revealed Mycobacterium avium intracellulare infection. The lesions resolved completely after a course of antibiotics.