Chronic graft-versus-host disease presenting as acute polymyositis: A case series and systematic review.

Chronic graft-versus-host disease (cGvHD) remains a significant complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Commonly targeted organs are skin, eyes, mouth, gastrointestinal tract, and liver. Muscular involvement and presentation as acute polymyositis (APM) remain a rare manifestation of cGvHD. We present a case series of three patients who presented with APM as a sole presentation of cGvHD and were treated successfully with corticosteroids and ruxolitinib. We also conducted a systematic review including 72 patients to summarize current literature regarding APM associated with cGvHD after allo-HSCT. The estimated incidence of cGvHD-associated APM is up to 3.4%, with a median time to onset of 1.6 years post-allo-HSCT. Most cases (85%) presented with myalgia and progressive bilateral proximal muscle weakness with elevated creatine kinase and/or aldolase. Over half of the patients had a prior history of acute GvHD. Isolated APM presenting without other clinical manifestations of cGvHD was rare. Biopsy of affected muscles usually shows characteristic myonecrosis, which remains the gold standard for diagnosis. Most cases respond to systemic steroids and immunosuppressive therapy. However, refractory cases remain challenging to treat and can cause significant morbidity and mortality. Ruxolitinib appears to be an effective therapy in this setting.