Co-occurrence of psoriatic arthritis with collagenous colitis: Clinicopathologic findings of a case

A 58-year-old man developed psoriatic arthritis and, after 6 months, persistent watery diarrhoea. Biopsies from the colorectal mucosa showed thickened subepithelial collagen consistent with collagenous colitis. There also was an inflammatory cell infiltration (mainly lymphocytes and monocytes) in the chorion. These findings and the parallel course of articular and bowel complaints suggest a clinicopathologic correlation between arthritis and colic involvement