Hepatic portal venous gas due to polystyrene sulfonate-induced enteritis.

A 78-year-old man with acute right lower abdominal pain and nausea was referred to our hospital. Computed tomography (CT) demonstrated hepatic portal venous gas and a thickened wall of the terminal ileum, and colonoscopy demonstrated ulcers and erosions of the ileocecal region. Histological examination of biopsy samples revealed basophilic crystals consistent with the component of calcium polystyrene sulfonate (CPS). This patient started taking CPS 2 months prior for chronic hyperkalemia. The symptoms resolved soon after ceasing CPS, and subsequent imaging studies confirmed the disappearance of the portal venous gas and ileocolitis.