Abstract
An 82-year-old man presented with high-grade fever, left flank pain with dysuria. Urine culture revealed the growth of Escherichia coli. Contrast-enhanced computed tomography features were suggestive of xanthogranulomatous pyelonephritis (XPN) of the left kidney. Serial hemogram studies revealed markedly raised white cell count with the presence of blast cells. On further evaluation by peripheral blood smears and bone marrow biopsy studies, a background disease setting of acute prolymphocytic leukemia was diagnosed. This is a very rare case report of acute leukemia masquerading as a case of XPN, and the optimum treatment protocol is yet to be established in such a scenario.