Multiple cystic lung lesions and autoimmune thrombocytopaenia developing after chemotherapy for pulmonary indolent B-cell lymphoma with plasmacytic differentiation.

Among lung malignancies, primary pulmonary lymphoma is rare and many of them are indolent B-cell lymphomas. We describe a case of primary pulmonary indolent B-cell lymphoma with plasmacytic differentiation, which exacerbated with the manifestation of macroglobulinaemia and was successfully treated using chemotherapy. The patient subsequently developed pulmonary cysts and thrombocytopaenia due to autoimmune pathology and was successfully treated using prednisolone. This case suggests that in indolent B-cell lymphoma with plasmacytic differentiation, immunoglobulin M level should be carefully followed even if it is within the normal range at lymphoma onset. Additionally, new cystic pulmonary infiltrates that develop during the post-treatment follow-up of an indolent pulmonary B-cell lymphoma may indicate pulmonary lymphoma recurrence, but there is also a possibility of an immunological complication. © BMJ Publishing Group Limited 2018. No commercial re-use. See rights and permissions. Published by BMJ.