S5147 Concurrent Herpes Simplex Virus Esophagitis and Cytomegalovirus Gastritis in an Immunocompromised Patient with Metastatic Endometrial Carcinoma and Immune Checkpoint Inhibitor Hepatitis

Introduction: Herpes simplex virus (HSV) and Cytomegalovirus (CMV) are common causes of gastrointestinal opportunistic infections in immunocompromised hosts. However, regardless of the degree or type of immunosuppression, coexisting opportunistic viral infections in the gastrointestinal tract remain rare. We present a case of concurrent HSV esophagitis and CMV gastritis in an immunocompromised patient. Case Description/Methods: A 67-year-old woman with metastatic endometrial carcinoma status post-surgical resection on adjuvant chemotherapy and immunotherapy complicated by immune checkpoint inhibitor (ICI) hepatitis treated with high-dose prednisone presented with recurrent abdominal pain worse in the right upper quadrant (RUQ) and exacerbated by eating. She denied fever, melena, dysphagia, or odynophagia. The physical examination was remarkable for RUQ and epigastric tenderness with a negative Murphy sign. Labs showed elevated white blood cell 14.4 and ANC 13,200, low absolute lymphocyte count 270 and an increase in her liver enzymes, reflecting her ICI-hepatitis. An abdominal ultrasound showed cholelithiasis, no portal vein thrombosis, and was otherwise normal. Intravenous pantoprazole was started. Endoscopic ultrasound was negative for obstructing stones or pancreaticobiliary dilatation, but it revealed pan-esophageal white nummular lesions and 3 non-bleeding gastric ulcers without stigmata of bleeding. Histopathology revealed esophageal squamous cells with HSV inclusions and ulcerated gastric antral mucosa with CMV inclusions, consistent with herpetic esophagitis and CMV gastritis. Additional fungal stains were negative. Valganciclovir was initiated for 21 days, leading to the resolution of abdominal pain. However, the patient continued to experience worsening liver enzyme elevations and was started on ursodiol, fenofibrate, and mycophenolate mofetil alongside a tapering steroid course with a favorable response. Discussion: The morbidity of HSV and CMV gastrointestinal infections is determined by the host immune response. The increasing utilization of ICI immunotherapy in cancer treatment has been associated with a parallel increase in immune-related adverse events (irAEs). Corticosteroid therapy for irAEs in cancer patients risks further worsening the severity of immunosuppression and predisposes patients to opportunistic infections. A high index of suspicion for concurrent gastrointestinal opportunistic infections is required in immunocompromised patients to reduce morbidity.