Successful treatment of lung cancer coexisting with B‑cell lymphoma with pembrolizumab following rituximab‑included chemotherapy: A case report.

The combined occurrence of lung cancer and B-cell lymphoma, such as mucosa-associated lymphoid tissue (MALT) lymphoma, is rare. The efficacy and safety of immune checkpoint inhibitors (ICIs) remain unknown in this population of patients, and the occurrence of ICI-induced exacerbation of lymphoma is concerning. The present study describes a case of successful treatment with pembrolizumab following rituximab-containing chemotherapy for lung cancer complicated by MALT lymphoma. The patient was a 69-year-old woman diagnosed with MALT lymphoma based on a biopsy of stomach ulcerative lesions, and advanced lung cancer based on a biopsy of a lymph node in the left pulmonary hilum. Complete remission was achieved after one cycle of rituximab and bendamustine therapy for MALT lymphoma. Pembrolizumab monotherapy was subsequently initiated, resulting in a good response for lung cancer without recurrence or exacerbation of the lymphoma. In conclusion, the present study suggested that pembrolizumab, following rituximab-containing therapy, could be a treatment option for patients with lung cancer coexisting with MALT lymphoma.