What happened, in summary

A 53-year-old man with Stage IV lung adenocarcinoma had already completed 4 cycles of cisplatin and pemetrexed and was receiving maintenance pemetrexed when he developed fever, fatigue and prolonged pancytopenia. Testing showed that the blood-count problem was not simply chemotherapy toxicity: bone-marrow examination identified visceral leishmaniasis. His lung cancer testing was negative for EGFR mutation, ALK, ROS and PD-L1. Maintenance pemetrexed was paused while he received treatment for the infection. Blood testing for Leishmania became negative after about 4 weeks. Two months into the interruption, chest imaging showed progression of the lung cancer, so pemetrexed was restarted even while anti-infective treatment continued. The restart was tolerated. The cancer therefore remained active and had progressed during the temporary break in systemic treatment, while the infection was managed separately.