Suspected Seronegative Spondyloarthropathy in a Young Woman With Ulcerative Colitis and Concurrent Bleeding Symptoms.

Extraintestinal musculoskeletal manifestations, including peripheral and axial spondyloarthritis, are well recognized in ulcerative colitis (UC) and are frequently associated with human leukocyte antigen B27 (HLA-B27) positivity. We present a 20-year-old woman with UC who developed inflammatory-pattern polyarthralgia involving the knees, ankles, wrists, shoulders, and lower back, with morning stiffness improving with movement, alongside bruising, menorrhagia, and mild leukopenia. Examination showed bilateral lower extremity ecchymoses and mild joint tenderness without swelling or synovitis. Laboratory evaluation showed positive HLA-B27, mildly elevated CRP, normal coagulation studies, and iron deficiency without anemia. Sacroiliac and knee radiographs were unremarkable; MRI was not obtained. von Willebrand disease, immune thrombocytopenia, and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis were considered less likely but not definitively excluded. Rheumatology evaluation supported a working diagnosis of inflammatory bowel disease (IBD)-associated seronegative spondyloarthropathy, with biologic therapy under consideration. This case illustrates the diagnostic complexity that arises when inflammatory musculoskeletal symptoms of IBD coexist with unexplained hematologic findings, and underscores the need for broad differential diagnosis and complete multidisciplinary evaluation before diagnostic closure.