title: Coexisting hybrid malignancy in a solitary sporadic solid benign renal mass: implications for treating patients following renal biopsy.
abstract: OBJECTIVE
  Concern regarding coexisting malignant pathology in benign renal tumors deters renal biopsy and questions its validity. We examined the rates of coexisting malignant and high grade pathology in resected benign solid solitary renal tumors.
  
  
  METHODS
  Using our prospectively maintained database we identified 1,829 patients with a solitary solid renal tumor who underwent surgical resection between 1994 and 2012. Lesions containing elements of renal oncocytoma, angiomyolipoma or another benign pathology formed the basis for this analysis. Patients with an oncocytic malignancy without classic oncocytoma and those with known hereditary syndromes were excluded from study.
  
  
  RESULTS
  We identified 147 patients with pathologically proven elements of renal oncocytoma (96), angiomyolipoma (44) or another solid benign pathology (7). Median tumor size was 3.0 cm (IQR 2.2-4.5). As quantified by the R.E.N.A.L. (radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior and location relative to polar lines) nephrometry score, tumor anatomical complexity was low in 28% of cases, moderate in 56% and high in 16%. Only 4 patients (2.7%) were documented as having hybrid malignant pathology, all involving chromophobe renal cell carcinoma in the setting of renal oncocytoma. At a median followup of 44 months (IQR 33-55) no patient with a hybrid tumor experienced regional or metastatic progression.
  
  
  CONCLUSIONS
  In our cohort of patients with a solitary, sporadic, solid benign renal mass fewer than 3% of tumors showed coexisting hybrid malignancy. Importantly, no patient harbored coexisting high grade pathology. These data suggest that uncertainty regarding hybrid malignant pathology coexisting with benign pathological components should not deter renal biopsy, especially in the elderly and comorbid populations.
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Serge
authors.initials: S
authors.lastname: Ginzburg
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Robert
authors.initials: R
authors.lastname: Uzzo
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Tahseen
authors.initials: T
authors.lastname: Al-Saleem
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Essel
authors.initials: E
authors.lastname: Dulaimi
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: John
authors.initials: J
authors.lastname: Walton
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Anthony
authors.initials: A
authors.lastname: Corcoran
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Plimack
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Reza
authors.initials: R
authors.lastname: Mehrazin
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Tomaszewski
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Viterbo
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: David Y T
authors.initials: DY
authors.lastname: Chen
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Richard
authors.initials: R
authors.lastname: Greenberg
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania.
authors.forename: Marc
authors.initials: M
authors.lastname: Smaldone
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center, Temple University, Philadelphia, Pennsylvania. Electronic address: Alexander.Kutikov@fccc.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kutikov
mesh_terms: D018249:Adenoma, Oxyphilic / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000368:Aged; D018207:Angiomyolipoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
keywords: AML; CK-7; PRB; RCC; RO; adenoma; angiomyolipoma; carcinoma; chRCC; chromophobe RCC; cytokeratin 7; kidney; oncocytoma; oxyphilic; pathology; percutaneous renal biopsy; renal cell; renal cell carcinoma; renal oncocytoma
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