2020-46 / November 16
Contributors: Bryan Morales-Vargas and Lara Harik

A woman in her early 50s presented with abdominal pain and was found to have an 8 cm left retroperitoneal mass on imaging. A resection including the mass and adjacent left kidney was performed.


1. What is the correct diagnosis?

a. Chromophobe renal cell carcinoma

b. Clear Cell Renal Cell Carcinoma

c. Epithelioid angiosarcoma

d. Epithelioid Angiomyolipoma

e. Extra Renal TFE3 Translocation-associated Renal Cell Carcinoma

1. Extra Renal TFE3 Translocation-associated Renal Cell Carcinoma

We present a rare case of extra-renal TFE3 translocation associated renal cell carcinoma. The specimen showed a multinodular dark red/black mass with intersecting fibrous bands, located outside the kidney, within the renal hilum adipose tissue. The mass measured 6.2 x 5.5 x 4.4 cm, involved the renal hilar fat, but did not involve the kidney, pelvicalyceal system, or ureter. The mass invaded into the renal vein to form a tumor thrombus. No gross or microscopic lesions were seen in the well sampled kidney. No renal masses were seen on imaging either. The interface of the mass and the kidney, was extensively sampled ruling out microscopic involvement of the kidney (image shows closest microscopic contact of mass and renal parenchyma).

Microscopically the tumor was well defined and composed of clear cells arranged in nests and microcysts,separated by delicate vasculature, in a hemorrhagic background. Neoplastic cells had well-defined borders, with abundant clear to pink cytoplasm, vesicular chromatin, and prominent nucleoli.

The carcinoma showed PAX-8 nuclear positivity, in keeping with renal origin, and diffuse nuclear positivity for TFE3, which triggered further studies.

The Archer Fusion Panel 26, which assesses the fusion status of multiple genes involved in various tumors, detected a TFE3-ASPSCR1 fusion, confirming the diagnosis of Xp11 translocation-associated renal cell carcinomas.

Extra-renal renal cell carcinomas are very rare, with few reported cases in the literature. They can be seen in both the pediatric and adult patient population. A variety of renal cell carcinoma subtypes are described including Clear Cell Renal Cell Carcinoma, Papillary Renal Cell Carcinoma and TFE3 Translocation-Associated Renal Cell Carcinoma. The origin of these extra-renal renal neoplasms is not clear with speculations on remnant renal tissue left behind during embryologic formation of the kidneys.

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Bryan Morales-Vargas, M.D. (
Lara R. Harik, M.D. ( , @LaraHarikMD)
Emory University School of Medicine, Atlanta, GA
Department of Pathology and Laboratory Medicine


Extra-renal cell carcinoma, Translocation-associated renal cell carcinoma, TFE3