Chronic graft-versus-host disease presenting as polymyositis after allogeneic hematopoietic cell transplantation for malignant lymphoma

A 56-year-old male patient, who was diagnosed with follicular lymphoma at a referral hospital, rapidly developed supraclavicular and abdominal tumors, and a biopsy at our institution revealed transformed follicular lymphoma. Cytogenetic studies revealed t(2;18)(p11.2;q21)/IGK::BCL2 with abnormalities of BCL6::non-IG and MYC::IGH translocations. Allogeneic reduced-intensity conditioning hematopoietic cell transplantation (HCT) during the non-remission phase was performed from his human leukocyte antigen (HLA)-identical sister, and their HLA expressed HLA-DRB1*15:02. However, the tumor remained present immediately after transplantation. Low-grade fever, myalgia primarily involving the trunk and proximal limbs, and generalized arthralgia developed one week after cyclosporine A (CyA) discontinuation, at 13 months post-transplantation. Laboratory tests indicated elevated creatine kinase, aldolase, C-reactive protein, and soluble interleukin-2 receptor levels. Moreover, antinuclear antibody, anti-rheumatoid factor, anti-Jo-1 antibody, and cytomegalovirus antigen were negative. Electromyographic examination and magnetic resonance imaging revealed myopathic abnormalities consistent with myositis diagnosis.18F-fluorodeoxyglucose-positron emission tomography combined with computed tomography revealed diffuse hypermetabolism in all major muscle groups without evidence of active lymphoma. In addition, muscle biopsy indicated features of myositis. Treatment for chronic graft-versus-host disease (cGVHD) presenting as polymyositis was initiated with prednisolone and CyA. This improved both clinical symptoms and laboratory findings. To date, there has been no recurrence of malignant lymphoma in the 10 years since the completion of allogeneic HCT. Polymyositis is a rare complication of cGVHD. The coexistence of female-to-male HCT and HLA-DRB1*15:02 expression may contribute to cGVHD development as well as a favorable graft-versus-lymphoma effect.