Alloimmune Myositis as Paraneoplastic Complication of an Oral Squamous Cell Carcinoma After Severe Chronic Graft vs Host Disease or a Manifestation of Chronic Graft vs Host Disease? A Case Report and Literature Discussion.

A 53-year-old female patient with acute myeloid leukemia developed severe chronic graft vs host disease (cGVHD) of the oral mucosa after allogeneic hematopoietic stem cell transplantation with leukoplakia and relapsing oral squamous cell carcinoma (SCC) of the tongue. cGVHD needed long-lasting immunosuppressive therapy; SCC was treated with radiation and surgery. Acute myeloid leukemia remained in complete remission. The patient developed a myositis with pain of all muscles as well as paraparesis with elevated creatine kinase and C-reactive protein and detection of antiskeletal muscle autoantibodies 3500 days after hematopoietic stem cell transplantation. No other clinical features of chronic GVHD were apparent at this time. Symptoms disappeared after treatment with corticosteroids but relapsed while tapering. Weekly therapy with the B-cell-depleting antibody rituximab was started and administered for 6 weeks. Symptoms disappeared again but partly returned after some weeks, so therapy with azathioprine was started. During therapy with azathioprine slow tapering of corticosteroids was possible and clinical symptoms remained absent. Here we present a case report and review of the literature on alloimmune myositis as paraneoplastic complication of an oral SCC of the tongue after severe chronic GVHD or as late manifestation of chronic GVHD itself.