Isolated tuberculosis of the spleen presenting with fever of unknown origin in a vaccinated child

Tuberculosis (TB) is one of the top 10 causes of death worldwide and is more common in developing countries. Isolated splenic TB is typically found in trauma, miliary TB and immunocompromised status. We present a very rare case of an immunocompetent child with an isolated primary TB in the spleen. The child only had fever of unknown origin (FUO), and mild anaemia. The diagnosis was not made until splenectomy was performed. The patient took the quadruple therapy for TB, and follow-ups showed no recurrence. This case is unique because this child was immunocompetent with no history of trauma or active TB. TB diagnosis should never be ignored in FUO as this might prevent unnecessary procedures to the patient. Although the child was vaccinated with Bacillus Calmette–Guérin that usually protects against severe TB in first 5 years of life, it did not prevent from affecting the spleen.