A man in his fifties with lymphoma, vomiting and diarrhoea.

BACKGROUND

Diagnosing immunosuppressed patients who present with fever and gastrointestinal symptoms can be particularly challenging for clinicians.

CASE PRESENTATION: We report the case of a man in his fifties who developed severe enterocolitis, immunosuppression and protein loss following treatment with rituximab and bendamustine. His medical history included recurrent iridocyclitis and small lymphocytic lymphoma, with subsequent identification of necrobiotic xanthogranuloma, prompting the initiation of chemoimmunotherapy. The patient initially presented with fever, vomiting and diarrhoea. Despite receiving appropriate medical care, he experienced recurrent infections and significant gastrointestinal distress, necessitating an extended hospital stay that involved interdisciplinary collaboration. Initial investigations indicated cytomegalovirus (CMV) reactivation, which was initially misinterpreted as CMV colitis. However, further biopsies revealed no classic CMV lesions, and comprehensive gastroenterological and microbiological evaluations ruled out infectious causes. This led to a diagnosis of rituximab-induced enterocolitis, a rare adverse effect of the treatment, confirmed by re-examination of the biopsies. Despite attempts to manage the condition with corticosteroids and TNF inhibitors, the patient ultimately succumbed to complications, including severe infections and renal failure.

INTERPRETATION: This case underscores the critical need to recognise rituximab-induced enterocolitis, especially in patients presenting with unexplained gastrointestinal symptoms during therapy. Timely diagnosis and intervention may improve patient outcomes, highlighting the necessity for vigilant monitoring of such patients.