Cytomegalovirus gastritis as a rare adverse event during combined ipilimumab and nivolumab in a patient with melanoma

Immunotherapy has improved survival outcomes of patients with advanced melanoma. Lower gastrointestinal tract immune-related adverse events (irAEs) are common during treatment; however, gastritis is not frequently observed. Herein, we report a case of severe cytomegalovirus (CMV)-related gastritis in a patient treated with ipilimumab and nivolumab for metastatic melanoma. This report presents a 60-year-old woman with stage IV BRAF wild-type melanoma. After the second course of ipilimumab-nivolumab, the patient reported epigastric discomfort after meals, anorexia, and subsequent nausea, vomiting, epigastric pain, and weight loss. Disease staging with PET/CT scan showed very good partial response and diffuse gastroduodenitis. The patient underwent esophagogastroduodenoscopy, showing severe esophageal candidiasis and diffuse hemorrhagic, edematous, and ulcerative mucosa in the whole gastric wall. Biopsies of the gastric wall were obtained. Before receipt of the final pathology report, the patient was empirically started on corticosteroids based on the clinical suspicion of immune-related gastritis, without improvement of symptoms. The hematoxylin-eosin staining demonstrated active gastritis with diffuse nuclear cytopathic viral inclusions in epithelial and interstitial cells; CMV infection was confirmed with immunohistochemical staining. The patient started ganciclovir and fluconazole, with rapid improvement of symptoms. This case presents a rare instance of CMV gastritis in a patient receiving combined anti-PD1 and anti-CTLA4 , in the absence of immune-suppression to manage an irAE. In the case of suggestive symptoms of irAEs, a high index of clinical suspicion is required to rule out concomitant or isolated infective disease. Guidelines for prophylaxis and treatment of these patients are needed, to optimize treatment results.