Androgen deprivation therapy caused a drastic proliferation of B-cell lymphoma with IgG4-related disease in patients with prostate cancer: a case report.

Background: We report a case of diffuse large B-cell lymphoma that progressed rapidly after androgen deprivation therapy for prostate cancer in a patient with a history of IgG4-related disease. Estrogen has been reported to be a possible cause of acute exacerbations of malignant lymphoma only in mouse models. Therefore, its clinical significance has not been clarified.

Case Presentation: This case report describes a 75-year-old man with prostate cancer who had IgG4-related disease. Hormone therapy was initiated to treat prostate cancer, but he developed dyspnea and back pain. A diagnosis was made of diffuse large B-cell lymphoma. Immunohistochemistry was positive for estrogen receptor β, which led us to suspect rapid progression of diffuse large B-cell lymphoma due to estrogen suppression by gonadotropin-releasing hormone antagonists. Hormone therapy was discontinued, and the patient received R-CHOP therapy. Subsequently, the lymphoma masses shrunk, and the patient obtained remission.

Conclusion: This case is the first report of clinical significance regarding the crucial role of estrogen and estrogen receptor β in malignant lymphoma in a patient with IgG4-related disease. Our report aims to raise awareness of the need to carefully select treatment options for prostate cancer patients with IgG4-related disease or lymphoma.