Isolated Splenic Tuberculosis with Possible Concurrent Scrub Typhus in an Immunocompetent Host: An Uncommon Case Report.

BACKGROUND: Isolated splenic tuberculosis is an exceptionally unusual clinical condition, particularly in immunocompetent patients, and frequently manifests with nonspecific clinical features that resemble other tropical illnesses. Diagnostic difficulties are exacerbated when concomitant diseases, such as scrub typhus, are present, potentially delaying suitable treatment. CASE PRESENTATION: We report the case of a 21-year-old immunocompetent female with a body mass index (BMI) of 22.8 kg/m², presenting with a three-week history of intermittent fever and left upper-quadrant abdominal pain. Clinical evaluation revealed splenomegaly, elevated inflammatory markers (C-reactive protein (CRP) 24 mg/L and raised erythrocyte sedimentation rate (ESR) of 28 mm/hr), and a positive paired serum sample for scrub typhus IgM serology, while the Mantoux test and chest imaging were unremarkable. Notwithstanding empirical treatment for enteric fever and subsequent doxycycline administration for scrub typhus, the fever persisted. Imaging revealed several hypodense splenic lesions consistent with abscesses. Acid-fast bacilli were identified in the aspirated material on staining, and the cartridge-based nucleic acid amplification test (CBNAAT) confirmed Mycobacterium tuberculosis with rifampicin sensitivity, establishing isolated splenic tuberculosis. The patient responded well to standard antitubercular therapy, with marked radiological improvement on follow-up. CONCLUSION: This case highlights the importance of considering tuberculosis as a possible aetiology of splenic abscesses, even in apparently immunocompetent individuals and in the presence of another possible tropical infection (scrub typhus IgM seropositive). Persistent fever, atypical imaging findings, or inadequate response to first therapy should necessitate assessment for co-infections. Early microbiological confirmation and timely treatment are essential to achieving optimal outcomes.