Acute polymyositis presenting as chronic graft-versus-host disease: A systemic review.

e19025 Background: Chronic graft-versus-host disease (cGvHD) remains a significant complication of allogenic hematopoietic stem cell transplantation (allo-HSCT), with an estimated incidence of over 50%. Commonly targeted organs are skin, eyes, mouth, gastrointestinal tract, and liver. Muscular involvement and presentation as acute polymyositis (APM) remains a rare manifestation of cGvHD. We present a systemic review of APM associated with cGvHD to summarize current evidence regarding epidemiology, clinical presentation, diagnosis, treatment, and prognosis. Methods: A systemic review was conducting following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We screened 97 articles from 3 databases (PubMed, Embase, and Cochrane) using the MeSH terms and keywords for “Allogenic stem cell transplantation,” “Chronic graft-versus-host disease,” “Polymyositis” and “Myositis” from the date of inception to Jan 2021. After excluding duplicate, review and non-relevant articles, we included 36 studies (3 retrospective, others case series/reports) reporting APM associated with cGvHD after allo-HSCT. Results: We identified 72 patients, presented with APM associated with cGvHD after allo-HSCT. It involves cases of all ages, with male predominance. The onset of APM ranges as early as 100 days to 5 years, with a median range of 1.6 years post-allo-HSCT. Over half (59%) of patients had prior acute GvHD. Majority (85%) of cases presented with myalgia and progressive bilateral proximal muscle weakness with elevated Creatine phosphokinase (CPK) and/or Aldolase. Isolated presentation of APM without other manifestations of GvHD was rare, and concurrent skin involvement was present in 42% cases. Steroids remain the mainstay of treatment, achieving complete treatment response in up to 78% of cases. In some refractory cases, Rituximab has also been effective. Conclusions: APM can present as a sole manifestation of cGvHD with an estimated incidence of up to 3.4%. Diagnosis can be challenging as it can mimic idiopathic polymyositis. Radiologically targeted muscle biopsy showing characteristic myonecrosis remains the gold standard for diagnosis. Most (90%) cases respond to steroids and immunosuppression agents. Nevertheless, refractory cases remain challenging to treat and can cause significant morbidity and mortality. Characteristics of APM in 3 cohorts of allo-HSCT patients.[Table: see text]