Abstract: SA-PO375
Extramedullary Hematopoiesis Misdiagnosed as Interstitial Nephritis in a Patient with Renal Dysfunction: A Case Report
Session Information
- Genetic and Diagnostic Trainee Case Reports
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1602 Pathology and Lab Medicine: Clinical
Authors
- Asou, Mea, Suwa Central Hospital, Chino, Japan
- Araki, Makoto, Suwa Central Hospital, Chino, Japan
Group or Team Name
- Suwa Central Hospital
Introduction
Extramedullary hematopoiesis is widely known to occur in patients with primary myelofibrosis (PMF). Autopsy studies on individuals with PMF revealed that extramedullary hematopoiesis occurred in the kidneys in 35% of the cases. However, there is little awareness regarding such lesions.
Case Description
A 63-year-old man was diagnosed with PMF (Dynamic International Prognostic Scoring System: intermediate-1-risk group) with a JAK2 V617F gene mutation based on a detailed examination of persistent white blood cells (white blood cell count, >10,000 /μL). An examination of the patient's medical records revealed a correlation between leukocytosis and deterioration of renal function and urinary protein. Thus, a kidney biopsy was performed. Advanced lymphocyte invasion was recognized in the interstitial tissue, and the uriniferous tubule extensively disappeared. Glomerular lesions were investigated, and only some were determined to have resulted from mesangial proliferative glomerulonephritis. Based on these findings, the pathologist diagnosed the patient with interstitial nephritis. However, because of the large number of cells with nuclear atypia in the stroma, additional immunohistochemical staining was also performed, such as Glycophorin A, Napthol AS-D, Myeloperoxidase and CD42b. As a result, invasion of three lineages of immature cells, erythroblasts, megakaryocytes, and granulocytes, was identified. Renal dysfunction resulting from interstitial cellular infiltration due to extramedullary hematopoiesis was therefore diagnosed. Treatment with ruxolitinib was initiated after a renal biopsy. The patient’s decrease in estimated glomerular function rate stabilized, and urinary protein concentration decreased slowly.
Discussion
Although, in myeloproliferative disorders, proliferative glomerular lesions are widely considered to be renal disorders, there is little awareness regarding interstitial lesions. Extramedullary hematopoiesis of the kidney in PMF is not uncommon, but 40% of cases are reportedly misdiagnosed as interstitial nephritis. Because extramedullary hematopoiesis can be controlled by treatment with ruxolitinib, early detection is important.