Cooccurrence of collagenous colitis with seronegative spondyloarthropathy: report of a case and literature review.

Collagenous colitis is an uncommon cause of chronic watery diarrhea, characterized by colonic deposition of collagen. Nonerosive, oligoarticular, peripheral arthritis has previously been noted in about 7% of patients with collagenous colitis. We describe a patient with collagenous colitis who concurrently developed erosive, seronegative spondyloarthropathy affecting peripheral and axial joints. Synovial histology was characterized by a conspicuous inflammatory infiltrate comprised of histiocytes, lymphocytes and plasma cells. Collagenous colitis is suggested to be a systemic autoimmune disorder, with extraintestinal features such as thyroiditis and arthritis.