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Kidney Week

Abstract: TH-PO547

Mastocytosis of the Kidney: A Rare Manifestation of Systemic Mastocytosis

Session Information

  • Trainee Case Reports - I
    October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Seipp, Regan M., Mayo Clinic , Phoenix, Arizona, United States
  • Keddis, Mira T., Mayo Clinic , Phoenix, Arizona, United States
  • Ryan, Margaret, Mayo Clinic , Phoenix, Arizona, United States
Introduction

Systemic mastocytosis (SM), a rare, progressive myeloproliferative neoplasm, is characterized by clonal mast cell infiltration into tissues. Renal involvement of SM is unusual, with only three case reports currently described in the literature, and carries a grim prognosis.

Case Description

A 71 year old male with a history of hypertension, presented with a one year history of fatigue, 60 lb. weight loss, and increasing abdominal distention. Physical exam was notable for a frail, cachectic male with hepatosplenomegaly and peripheral edema. Laboratory analysis revealed acute kidney injury, decreased hepatic synthetic function, and pancytopenia. Urinalysis displayed grade 1 proteinuria and granular casts. Abdominal ultrasound showed increased echogenicity of the kidneys, ascites, and hepatic cirrhosis. The patient had no known risk factors for liver disease and underwent liver biopsy demonstrating diffuse mast cell infiltration with pericentral hepatocyte necrosis. Serum tryptase levels were elevated: 203 ng/ml (normal <11.5). Ensuing bone marrow biopsy showed 100% cellularity with 30-40% mast cells, confirming the diagnosis of SM. The kidney injury, initially managed as hepatorenal syndrome with albumin, midodrine, and octreotide, rapidly progressed requiring hemodialysis. Kidney biopsy revealed tubular injury and mast cell interstitial nephritis (Image 1). Midostaurin, a multikinase inhibitor, was initiated as disease directed therapy. The patient was eventually discharged but remained dialysis dependent.

Discussion

SM is associated with mutations in the receptor tyrosine kinase KIT (CD117). SM subtypes and median survival range from indolent (16 years) to mastocytoma (2 months). Renal involvement may occur even with indolent SM and has been reported as MPGN, interstitial nephritis, and light chain deposition disease. In each case, the kidney injury was progressive, requiring hemodialysis, and survival was worse than expected despite KIT directed therapy.

Image 2: Kidney biopsy CD117 stain highlighting increased interstitial mast cells