Cryptic clues from an acute abdomen: a case report of peritonitis turning into disseminated cryptococcosis

Abstract Background Cryptococcosis is a life-threatening opportunistic fungal infection that primarily affects immunocompromised individuals, most commonly presenting as meningitis. Peritoneal involvement is exceedingly rare and can closely mimic common acute surgical conditions, often resulting in delayed diagnosis and treatment. This case describes an unusual presentation of disseminated cryptococcosis as acute peritonitis with subsequent progression to cryptococcal meningitis; underscoring the diagnostic challenges posed by atypical intra-abdominal infection. Case presentation A previously healthy female homemaker in her late 20s presented with a 20-day history of intermittent low-grade fever, followed by 7 days of right lower abdominal pain and multiple episodes of non-projectile vomiting. Clinical examination revealed right iliac fossa tenderness with guarding and rebound tenderness, suggestive of acute appendicitis with perforation. Her pre-operative laboratory work-up revealed HIV positivity and emergency laparotomy with open appendicectomy and drainage of pelvic abscess was performed. Histopathological examination demonstrated granulomatous inflammation with encapsulated yeast forms consistent with Cryptococcus neoformans , later confirmed by special fungal stains. On postoperative day 3, the patient developed headache and neck stiffness. Subsequent evaluation identified disseminated cryptococcosis with cryptococcal meningitis, mesenteric lymphadenitis, and urinary tract involvement, alongside newly diagnosed advanced HIV infection with CD4 cell count of 98 cells/mm³. The patient received amphotericin B-based induction antifungal therapy followed by prolonged fluconazole consolidation and maintenance therapy. Antiretroviral treatment was initiated in a deferred manner after stabilisation to avoid IRIS related complications. Clinical improvement was observed with resolution of symptoms and significant immunological recovery during follow-up with no residual complications. Conclusions This case illustrates an exceptionally rare presentation of disseminated cryptococcosis manifesting initially as acute peritonitis and later progressing to central nervous system involvement. To our knowledge, this is the first reported case where peritonitis precedes systemic involvement and meningitis in cryptococcosis clinically in HIV positive patients. It emphasizes the importance of maintaining a high index of clinical suspicion for opportunistic fungal infections in atypical or non-resolving intra-abdominal infections, particularly in patients with undiagnosed immunosuppression. Early histopathological recognition, timely antifungal therapy, and coordinated management of underlying HIV infection are critical for improving outcomes.