[863] Molecular Assessment of Clonality in Mixed Epithelial and Stromal Tumors of the Kidney: Evidence for a Single Cell of Origin with Capacity for Epithelial and Stromal Differentiation.

Jennifer B Kum, Mingsheng Wang, David J Grignon, Ming Zhou, Rodolfo Montironi, Steven Shen, Antonio Lopez-Beltran, John N Eble, Liang Cheng. Indiana University, Indianapolis; Cleveland Clinic, OH; Polytechnic University of the Marche Region, Ancona, Italy; The Methodist Hospital, Houston, TX; Cordoba University, Spain

Background: Mixed epithelial and stromal tumors of the kidney (MESTK) are uncommon biphasic tumors of the kidney with cystic and solid areas composed of ovarian-like stroma and an epithelial component with variable morphology. Little is known about the pathobiology and molecular features of these tumors. There are two theories regarding the development of the tumor. One theory proposes that the stroma is neoplastic but the epithelium represents "trapped" structures and is not clonal. Another theory proposes that both the stroma and epithelium are neoplastic and arise from a common cell of origin.
Design: A total of 21 MESTK tumors from female patients who underwent radical or partial nephrectomies were examined. The epithelial and stromal components of MESTK, as well as adjacent non-neoplastic renal parenchymal tissues were separately laser microdissected from sections prepared from formalin-fixed and paraffin-embedded tissues. X-chromosome inactivation analysis was performed by examination for random or nonrandom inactivation methylation patterns of exon 1 of the human androgen receptor gene on chromosome Xq11-12.
Results: Nineteen of the 21 tumors were informative. Seven of these informative cases showed random X chromosome inactivation pattern in both epithelial and stromal component of MESTK. Nonrandom inactivation of the X-chromosome was found in 12 of 19 informative tumors. The same pattern of nonrandom inactivation of the X-chromosome was seen in both epithelial and stromal components in all 12 of the tumors with nonrandom X-chromosome inactivation.
Conclusions: MESTK are clonal tumors with the stroma and epithelium showing the same pattern of X-chromosome inactivation. Our data support the theory that the stroma and epithelium arise from a common cell of origin.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 110, Monday Morning


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