title: Polycythemia vera as a presentation of renal angiomyolipoma: a case report.
abstract: BACKGROUND
  Angiomyolipoma is a common benign renal tumor composed of thick-walled blood vessels, smooth muscle, and adipose tissue. It may be found incidentally during workup for suspected renal disease. Although angiomyolipoma may present as a palpable, tender renal mass with flank pain and gross or microscopic hematuria, many patients are asymptomatic. Erythrocytosis is an unusual presentation, and malignant transformation may be suspected. This report describes a rare case of a woman diagnosed with renal angiomyolipoma and polycythemia vera. The report discusses the differential diagnosis using erythropoietin, erythropoietin-receptor and Janus kinase 2.
  
  
  METHODS
  A 79-year-old Chinese woman was diagnosed with erythrocytosis according to World Health Organization criteria. An upper left renal pole angiomyolipoma was successfully ablated after multiple phlebotomy treatments. Red cell count immediately returned to normal, but gradually increased after 4 months. Polycythemia vera was finally diagnosed by positive mutation of Janus kinase 2 and negative erythropoietin protein expression. Her clinical symptoms improved with regular phlebotomy and hydroxyurea treatment.
  
  
  CONCLUSIONS
  Concurrent occurence of angiomyolipoma and polycythemia vera is rare. Polycythemia vera can be easily missed. Polycythemia vera can be confirmed with high specificity and sensitivity by the acquired somatic mutation. Surgical intervention for this renal tumor should be avoided unless malignancy or renal cell carcinoma is suspected or to prevent spontaneous rupture of larger tumors.
authors: Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan.
authors: Ming-Shyan
authors: MS
authors: Lin
authors: Yu-Shin
authors: YS
authors: Hung
authors: Hsueh-Hua
authors: HH
authors: Wu
authors: Ming-Chung
authors: MC
authors: Kuo
authors: Tzu-Fang
authors: TF
authors: Shiu
authors: Cheng-Keng
authors: CK
authors: Chuang
authors: Lee-Yung
authors: LY
authors: Shih
authors: Pao-Hsien
authors: PH
authors: Chu