Mycobacterium kansasii in cancer patients: a 13-case series

Mycobacterium kansasii comprises one of the most common and most pathogenic nontuberculous mycobacteria, particularly in immunocompromised individuals. This retrospective observational study aimed to describe the epidemiology, clinical characteristics, and outcomes of M. kansasii infections in 13 cancer patients from Instituto do Cancer do Estado de Sao Paulo, Brazil, from January 2011 to September 2023. Of the 19 initial positive cultures, 13 fully met diagnostic criteria for M. kansasii infections. Solid tumors occurred the most (69.2%), and only 38.4% of patients were undergoing chemotherapy at diagnosis. Smoking was the most frequent previous characteristic in these cases (76.9%). Fever (53.4%), cough (46.1%) and dyspnea (30.7%) were the most common symptoms. Multiple nodules (46.1%) and cavities (46.1%) were the most common radiological findings. Overall, seven patients (53.8%) received at least 12 months of therapy. One-year overall mortality totaled 38.4-22.2% in patients with solid tumors and 75% in patients with hematologic malignancies. In conclusion, M. kansasii infections were predominantly pulmonary in this series of cancer patients, which showed a high frequency of other respiratory comorbidities, especially smoking. Mortality occurred in several patients, particularly among those with hematological malignancies.