Microscopic description:

The cells are arranged in solid sheets and nests with cysts in between. These cysts are lined by single layer of cells with voluminous eosinophilic granular cytoplasm.

The solid areas shows variably-sized cells with eccentrically placed nuclei and eosinophilic voluminous at places flocculent and granular cytoplasm.

IHC was positive for CK20, PAX8, CD10, FH, SDHB and negative for CK7 and Melan A.

Discussion:

ESC-RCC was recently listed as a new and rare RCC type by the 2022 WHO kidney tumor classification.

Incidence rate is approximately 0.2%.

Age onset range from 14 to 79, with an average of 79 years, usually female patients.

At first it was suggested that ESC-RCC was associated Tuberous Sclerosis (TSC), but then it was found out that they do not commonly co-occur together and that around only 10% of patients with ESC-RCC have TSC.

ESC-RCC is an indolent neoplasm with good prognosis and low metastatic potential.

It is most commonly asymptomatic and found incidentally, and if symptomatic, the symptoms are non-specific.

Treatment is surgical with partial or total nephrectomy depending on the staging.

Grossly, these tumors appear as solid and cystic, yellow-gray mass with variable sizes.

Microscopically, it appears solid with multiple variably-sized cysts. The cells have eosinophilic cytoplasm with basophilic granular cytoplasmic stippling and round-to-oval nuclei.

Table of IHC stains used
References:

He, X., Chen, Y., Tang, H. et al. Eosinophilic solid and cystic renal cell carcinoma with TSC2 mutation: a case report and literature review. Diagn Pathol 18, 53 (2023). https://doi.org/10.1186/s13000-023-01341-9

Trpkov K, Abou-Ouf H, Hes O, Lopez JI, Nesi G, Comperat E, Sibony M, Osunkoya AO, Zhou M, Gokden N, Leroy X, Berney DM, Werneck Cunha I, Musto ML, Athanazio DA, Yilmaz A, Donnelly B, Hyndman E, Gill AJ, McKenney JK, Bismar TA. 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 Oct;41(10):1299-1308. doi: 10.1097/PAS.0000000000000838. PMID: 28786877.

Palsgrove D, Argani P. Eosinophilic, solid and cystic. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneytumorescrcc.html. Accessed July 31st, 2023.

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