680 An Incidental Finding of Pneumatosis of the Colon in a Patient with Mesothelioma Being Treated with Nivolumab Free

A 75-year-old woman attended a large academic teaching hospital for a computed tomography (CT) of the chest for a T3 N0 M0 epithelioid mesothelioma of the right pleura (to assess treatment response). The malignancy was diagnosed one year previously, and the patient was being treated with second line immunotherapy, Nivolumab (a human immunoglobulin G4 monoclonal antibody) with palliative intent. To date, the patient was showing a partial response to this treatment.

The CT chest incidentally showed locules of gas under the right diaphragm and therefore an urgent CT of the abdomen and pelvis was performed. This scan re-demonstrated a small pneumoperitoneum, but also an incidental finding of pneumatosis involving the hepatic flexure. Prior to Nivolumab treatment, there were no abnormalities noted on the most recent abdominal CT scan.

The patient was admitted to hospital as an emergency under the care of oncology. The patient was entirely asymptomatic with a soft, non-tender abdomen, with both a normal diet and bowel function. Observations including heart rate, temperature, blood pressure and respiratory rate were within normal limits. Blood testing showed a C-reactive protein of 86 mg/L and white cell count of 4.8 10^9. Based on the radiological findings, intravenous fluids and antibiotics were commenced and the patient was restricted to nil intake orally. A surgical review was also requested. Based on surgical advice, the patient was treated conservatively, and was discharged home without complication and no surgical follow up.