Flucytosine-induced colitis mimicking a flare of ulcerative colitis: a diagnostic challenge in pulmonary cryptococcal infection.

Flucytosine-induced colitis is exceedingly rare with very few cases reported in the literature. We present a case of a 56-year-old male with history of ulcerative colitis and seronegative spondyloarthropathy who developed abdominal pain, diarrhoea and rectal bleeding following commencement of flucytosine and amphotericin B for cryptococcal empyema. The clinical features and biochemistry initially raised concern for an ulcerative colitis flare. Histopathology demonstrated features of an acute colitis. Subsequent cessation of flucytosine without alteration to management of his underlying ulcerative colitis led to a rapid and complete resolution of symptoms, supporting a diagnosis of flucytosine-induced colitis. This case highlights the importance of considering a drug-induced colitis in patients with inflammatory bowel disease presenting with new or worsening gastrointestinal symptoms. Accurate differentiation from disease flare is essential to avoid unnecessary changes or escalation in immunosuppressive therapy.