B-Cell Acute Lymphoblastic Leukaemia Presenting With Bilateral Renal Enlargement.

Acute lymphoblastic leukaemia (ALL) is the most common paediatric malignancy. While extramedullary manifestations can occur, renal infiltration is rare. We report the case of a previously healthy one-year-old girl who presented with a two-week history of intermittent fever, lethargy, and progressive abdominal distension. On examination, she was lethargic, with bilateral palpable abdominal masses. Laboratory investigations revealed leukocytosis, bicytopenia, and abnormal urinalysis. A peripheral blood film and flow cytometry confirmed B-cell ALL. Ultrasonography demonstrated bilateral renal enlargement, suggestive of leukemic infiltration. Despite massive nephromegaly, she maintained normal renal function, fluid balance, blood pressure, and urine output. Her nephromegaly resolved clinically within four weeks of initiation of multi-agent chemotherapy. Renal involvement in ALL is an uncommon extramedullary manifestation, often asymptomatic and incidentally discovered on imaging. The majority of reported cases show that leukemic infiltration of the kidneys typically does not impair renal function. Nephromegaly in ALL has no established prognostic significance, with most cases resolving following chemotherapy initiation. This case highlights the importance of considering ALL in the differential diagnosis of paediatric patients presenting with unexplained nephromegaly and/or abdominal masses. Although renal dysfunction in this context is rare, close monitoring and careful management to prevent tumor lysis syndrome are of paramount importance to optimise outcomes.