title: Correcting the Shrinkage Effects of Formalin Fixation and Tissue Processing for Renal Tumors: toward Standardization of Pathological Reporting of Tumor Size.
abstract: Given the importance of correctly staging renal cell carcinomas, specific guidelines should be in place for tumor size measurement. While a standard means of renal tumor measurement has not been established, intuitively, tumor size should be based on fresh measurements. We sought to assess the accuracy of postfixation and microscopic measurements of renal tumor size, as compared to fresh measurements and radiographic size. Thirty-four nephrectomy cases performed by a single surgeon were prospectively measured at different time points. The study cases included 23 clear cell renal cell carcinomas, 6 papillary renal cell carcinomas, and 5 other renal tumors. Radiologic tumors were 12.1% larger in diameter than fresh tumors (P<0.01). Furthermore, fresh specimens were 4.6% larger than formalin-fixed specimens (P<0.01), and postfixation measurements were 7.1% greater than microscopic measurements (P<0.01). The overall mean percentage of shrinkage between fresh and histological specimens was 11.4% (P<0.01). Histological processing would cause a tumor stage shift from pT1b to pT1a for two tumors in this study. The shrinkage effects of formalin fixation and histological processing may result in understaging of renal cell carcinomas. The shrinkage factor should be considered when reporting tumor size.
authors.affiliation: 1. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Thu
authors.initials: T
authors.lastname: Tran
authors.affiliation: 2. Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Chandru P
authors.initials: CP
authors.lastname: Sundaram
authors.affiliation: 2. Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Clinton D
authors.initials: CD
authors.lastname: Bahler
authors.affiliation: 1. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: John N
authors.initials: JN
authors.lastname: Eble
authors.affiliation: 1. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Grignon
authors.affiliation: 2. Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: M Francesca
authors.initials: MF
authors.lastname: Monn
authors.affiliation: 1. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Novae B
authors.initials: NB
authors.lastname: Simper
authors.affiliation: 1. Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA ; 2. Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
keywords: Kidney; pathologic staging; radiographic size; renal cell carcinoma; tissue processing shrinkage; tumor size measurement