S3789 Cytomegalovirus Masquerading as Malignancy in a Patient With Systemic Lupus Erythematosus

Introduction: Cytomegalovirus (CMV) infection is an opportunistic infection in both immunocompromised and immunocompetent patients, associated with significant morbidity and mortality. CMV can cause gastrointestinal lesions, particularly in immunosuppressed patients, which typically present as ulcerations or erosions. Rarely, CMV proctitis may present as a discrete mass mimicking adenocarcinoma. We describe a patient with systemic lupus erythematosus (SLE) who presented with hematochezia and was found to have a rectal mass highly suspicious for malignancy. However, further evaluation ultimately revealed a diagnosis of CMV proctitis. Case Description/Methods: Our patient is a 57-year-old woman with history of SLE on chronic steroids who initially presented with concern for bloody stools and pre-syncopal symptoms. Throughout the hospitalization, she had several episodes of maroon stool and hematochezia, with continued hemodynamic stability. Further evaluation included both upper endoscopy and colonoscopy. Upper endoscopy demonstrated antral gastritis and colonoscopy revealed an oozing, fungating, and ulcerated non-obstructive 1 cm rectal mass, concerning for malignancy. Pathology revealed CMV colitis. She started on intravenous ganciclovir and transitioned to oral valganciclovir at discharge for a total of 21 days. Discussion: CMV infection is an important opportunistic pathogen, particularly in immunocompromised individuals, including those on chronic steroids. While CMV commonly causes gastrointestinal ulcerations and erosions, the presentation of CMV proctitis as a discrete mass is rare and can lead to diagnostic uncertainty. Similar cases have been reported, where CMV-induced inflammatory changes and ulcerated lesions form mass-like structures, often leading to unnecessary surgical interventions or delays in treatment. Given that CMV can mimic malignancy both endoscopically and radiographically, histopathological confirmation with staining for CMV inclusion bodies is crucial for diagnosis. Gastrointestinal CMV infections in immunosuppressed patients can result in severe morbidity, including hemorrhage and perforation, if left untreated. In our case, prompt identification of CMV proctitis allowed for targeted antiviral therapy with ganciclovir. This case underscores the importance of considering CMV infection in the differential diagnosis of rectal masses. Early recognition and appropriate treatment can prevent unnecessary surgical interventions and improve outcomes.