Gastrointestinal: Cytomegalovirus enteritis with severe hypoalbuminemia in an immunocompetent patient

A 70-year-old man, previously treated for hypertension and diabetes mellitus, presented with a 3-month history of diarrhea and sought care at an outpatient clinic. Blood tests revealed severe hypoalbuminemia (albumin: 1.3 mg/dL). Although urinalysis and renal function test findings were normal, the C-reactive protein and white blood cell levels were mildly elevated (white blood cells: 10, 080 cells/μL; C-reactive protein: 0.8 mg/dL; estimated glomerular filtration rate: 75 mL/min). The diabetes was well controlled (glycated hemoglobin A1c: 5.7 mg/dL). Upon admission to our hospital for further investigation, contrast-enhanced computed tomography revealed wall thickening predominantly in the proximal jejunum (Fig. 1a,b). Subsequent capsule endoscopy and double-balloon enteroscopy showed multiple white moss and circular ulcers in the jejunum (Fig. 1c,d). Based on the disease progression and computed tomography and endoscopic findings, malignant lymphoma was considered the most likely cause. However, pathological findings of biopsy specimens revealed nuclear inclusion bodies and intracytoplasmic inclusion bodies (owl-eye-like) (Fig. 1e,f). No abnormal findings were observed in the colon. Blood cytomegalovirus (CMV) antigen and CMV-IgG (250 AU/mL) were positive, while CMV-IgM (0.53 S/CO) was negative. Therefore, the patient was diagnosed with CMV enteritis due to CMV reactivation. Symptoms, including severe diarrhea and hypoalbuminemia, significantly improved after ganciclovir administration for 3 weeks. Two weeks later, a follow-up double-balloon enteroscopy revealed improvement in edema and erythema, along with a reduction in white moss (Fig. 2). The incidence of small intestinal CMV infections is 4%, rendering them rarer compared with infections in other portions of the gastrointestinal tract.1 In recently reported cases, the major symptoms were abdominal pain and bleeding.2 An important risk factor for CMV infection is an immunocompromised status. However, in our case, diarrhea and hypoalbuminemia were the main symptoms, which are rare. This highlights the significance of considering CMV-induced small bowel inflammation as a possible cause of enteritis of unknown origin with severe hypoalbuminemia in an immunocompetent person.