Focal Segmental Glomerulosclerosis in a Patient with Prefibrotic Primary Myelofibrosis

We report a case of 56-year-old man presented to us with chief complaints of frothy urine and leg swelling. A urinalysis revealed nephrotic-range proteinuria. Haematological investigations revealed thrombocytosis, leucocytosis and peripheral blood smear showed a leucoerythroblastic picture. JAK 2 mutation was positive. To confirm the diagnosis of myeloproliferative neoplasm, bone marrow biopsy was done, which was suggestive of primary myelofibrosis. The patient underwent kidney biopsy due to rapidly declining renal function and persistent proteinuria, which was suggestive of focal segmental glomerulosclerosis. Early glomerulopathy is rare in myeloproliferative neoplasm, and aggressive follow-up is required to prevent progression of kidney disease.