Eosinophilic Solid and Cystic Renal Cell Carcinoma: An Emerging Renal Entity with Distinct Features - Beyond the Abstract

Eosinophilic solid and cystic renal cell carcinoma (ESC RCC) is a recently described, emerging renal entity, which demonstrates distinct clinical, pathological and molecular features.1-3 Our recent publication with the collaborators from Brazil highlights the imaging features of two previously undocumented ESC RCC.4  We found two distinct imaging patterns that varied depending on the histopathologic features (solid or cystic predominance). Recognition of the imaging characteristics and pathologic correlation of this novel neoplasm will contribute to its increasing recognition in practice. The true incidence is currently difficult to establish because many of these cases in the past have probably been either misdiagnosed or labeled as “unclassified renal cell carcinoma”. Owing to its very recent description, this entity is currently not included in the 2016 WHO Classification of the tumors of the genitourinary tract.   

What have we learned so far about ESC RCC? We are currently aware of approximately 60 sporadic ESC RCCs (including our personal files and published cases), collected through a broad international collaboration. About 10% of them occur in patients with documented Tuberous Sclerosis Complex (TSC), but the great majority are sporadic and not associated with TSC.1-3 The patients are typically females exhibiting broad age range; only rare cases have been documented in males. ESC RCC shows a characteristic morphology, with often tan, solid and cystic gross appearance, with cells exhibiting eosinophilic, voluminous cytoplasm demonstrating coarse granular stippling (Fig. 1A-C). These neoplasms are typically solitary, although occasional multifocality was observed. The tumors are frequently relatively small and low stage, although rare cases may show larger size. On Immunohistochemistry, there is frequent CK20 positivity, while CK7 is usually negative or only focally positive (Fig. 1D). ESC RCC demonstrates molecular karyotype profile of a recurring set of genomic alterations, which is different from the currently recognized renal neoplasms.2 Frequent copy number gains were found at 16p13-16q23, 7p21 -7q36, 13q14 and 19p12 and frequent copy number losses were documented at Xp11.21 and 22q11.2 Loss of heterozygosity alterations were identified at 16p11.2-11.1, Xq11-13, Xq13-21, 11p11, 9q21-22 and 9q33.2  

Although great majority of ESC RCC exhibit indolent behavior, two cases have been recently documented with metastatic disease (approximately 3%), which confirms the need for clinical surveillance on an RCC protocol in these patients.5,6 Additional studies are needed to fully characterize this entity, because up to date, there is a limited number of well-documented cases with sufficient follow up. With the growing recognition of this emerging renal entity, we expect that further evidence will be collected to fully validate and establish ESC RCC it as a novel renal neoplasm. 

Imaging Features of a Novel Neoplasm img1a
Figure 1: A) Eosinophilic solid and cystic renal cell carcinoma (ESC RCC) shows solid and cystic appearance at low power. B) The septae between the cysts vary in thickness and are composed of eosinophilic (pink) cells, with voluminous cytoplasm; the lining cells often show hobnail arrangement. C) The neoplastic cells typically show coarse cytoplasmic granularity (stippling), consisting of basophilic to purple cytoplasmic granules, which are readily recognizable at higher magnification in all cases. D) Typical immunophenotypic profile found in great majority of ESC RCC includes cytokeratin 20 positivity (shown) and cytokeratin 7 negativity (not shown).

Written by: Kiril Trpkov, MD, FRCPC Department of Pathology and Laboratory Medicine, University of Calgary, Calgary Laboratory Services, Calgary, Alberta, Canada

References:

1. Trpkov K, Hes O, Bonert M, et al. Eosinophilic Solid and Cystic Renal Cell Carcinoma: Clinicopathologic Study of 16 Unique, Sporadic Neoplasms Occurring in Women. Am J Surg Pathol 2016;40:60-71.

2. Trpkov K, Abou-Ouf H, Hes O, et al. Eosinophilic Solid and Cystic Renal Cell Carcinoma (ESC RCC): Further Morphologic and Molecular Characterization of ESC RCC as a Distinct Entity. Am J Surg Pathol 2017;41:1299-308.

3. Guo J, Tretiakova MS, Troxell ML, et al. Tuberous sclerosis-associated renal cell carcinoma: a clinicopathologic study of 57 separate carcinomas in 18 patients. Am J Surg Pathol 2014;38:1457-67.

4. Fenelon SS, Santos JMMM, Faraj SF et al. Eosinophilic Solid and Cystic Renal Cell Carcinoma: Imaging Features of a Novel Neoplasm. Urology 2018, Jan 29. pii: S0090-4295(18)30065-7. doi: 10.1016/j.urology. 2018.01.020. [Epub ahead of print]

5.  Li Y, Reuter VE, Matoso A, et al. Re-evaluation of 33 'Unclassified' Eosinophilic Renal Cell Carcinomas in Young patients. Histopathology  2017, Sep 12. doi: 10.1111/his.13395. [Epub ahead of print] 

6. McKenney JK, Przybycin C, Trpkov K, Magi-Galluzzi C. Eosinophilic Solid and Cystic (ESC) Renal Cell Carcinomas Have Metastatic Potential. Histopathology 2017 Dec 19. doi: 10.1111/his.13457. [Epub ahead of print]


Read the Abstract
E-Newsletters

Newsletter subscription

Free Daily and Weekly newsletters offered by content of interest

The fields of GU Oncology and Urology are rapidly advancing. Sign up today for articles, videos, conference highlights and abstracts from peer-review publications by disease and condition delivered to your inbox and read on the go.

Subscribe