[1031] Impact of Histologic Cystic Features in Clear Cell RCC (CCRCC) and Multilocular Cystic RCC (MCRCC) or Shall We Say – Neoplasm of Low Malignant Potential?

Maria Tretiakova, Vikas Mehta, Steven S Shen, Sahussapont Joseph Sirintrapun, Jorge L Yao, Isabel Alvarado-Cabrero, Scott E Eggener, Arieh L Shalhav, Tatjana Antic, Maria M Picken, Gladell P Paner. University of Chicago, Chicago; Loyola University Medical Center, Maywood; Methodist Hospital, Houston; Wake Forest University, Winston Salem; University of Rochester, Rochester; National Medical Center, Mexico City, Mexico

Background: MCRCC as defined in the 2004 WHO classification is recognized as a tumor with excellent prognosis. However, the clinicopathological data for MCRCC remains limited. In addition, pathologic studies that specifically assesses the influence of histologic cystic change when partly present in CCRCC is also limited.
Design: The clinicopathological features of 46 MCRCC (from 6 institutions), 85 partially cystic CCRCC (from 2 institutions) and 47 solid CCRCC (as control) are herein presented. CCRCC with cystic change due to necrosis were not included.
Results: Patient mean ages were as follows: MCRCC (59.7 yrs.), partially cystic CCRCC, (60.9 yrs.) and solid CCRCC (58.6 yrs.). Cystic change in partially cystic CCRCC was ≥ 25% of the tumor. The cysts were predominantly septated, multilocular, and contained variable amount of fluid. Fuhrman nuclear grades were 1 (82%) or 2 (18%) for all MCRCC; for partially cystic CCRCC were 1 (22%), 2 (69%), 3 (9%) and 4 (0%); and for solid CCRCC were 1 (9%), 2 (53%), 3 (25%) and 4 (13%). All MCRCC were either AJCC pT stage 1 (96%) or 2 (4%). pT stage for partially cystic CCRCC were 1 (91%), 2 (2%), 3 (7%) and 4 (0%) and for solid CCRCC were 1 (60%), 2 (6%), 3 (34%) and 4 (0%). Sarcomatoid change was present only in solid CCRCC (4%). Follow up for MCRCC (excluding those with synchronous RCC) (available in 40/46 cases; mean 49.6 mos) showed no recurrence or metastasis. Follow up for partially cystic CCRCC (available in 75/85 cases; mean 55.5 mos) showed 4% recurrence and 1% metastasis. None of the patients with MCRCC or partially cystic CCRCC died of disease during the follow-up. In contrast, patients with solid CCRCC (available in 35/47 cases; mean 48.4 mos) showed 37% recurrence, 51% metastasis and 6% death rate.
Conclusions: This large series of MCRCC shows lower stage and grade and reaffirms its indolent behavior, and thus, supports a prior proposal of renaming this tumor in its pure form as multilocular cystic renal cell neoplasm of low malignant potential. Our results also showed that CCRCC with cystic change is associated with lower grade, lower pathologic stage, and confers better prognosis than solid CCRCC. We recommend that presence and extent of cystic changes be documented as a separate variable in the surgical pathology reporting of CCRCC.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 135, Monday Morning

 

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