Clear-cell renal-cell carcinoma explained

Clear-cell renal-cell carcinoma (CCRCC) is a type of renal-cell carcinoma.

Genetics

Cytogenetics

• Alterations of chromosome 3p segments occurs in 70–90% of CCRCCs
• Inactivation of von Hippel–Lindau disease (VHL) gene by gene mutation and promoter hypermethylation
• Gain of chromosome 5q
• Loss of chromosomes 8p, 9p, and 14q

Molecular genetics

Several frequently mutated genes were discovered in CCRCC: VHL, KDM6A/UTX, SETD2, KDM5C/JARID1C and MLL2. PBRM1 is also commonly mutated in CCRCC.

Histogenesis

CCRCC is derived from the proximal convoluted tubule.

Microscopy

Generally, the cells have a clear cytoplasm, are surrounded by a distinct cell membrane and contain round and uniform nuclei.

Microscopically, CCRCCs are graded by the ISUP/WHO as follows:^{[1] [2]}

• Grade 1: Inconspicuous and basophilic nucleoli at magnification of 400 times
• Grade 2: Clearly visible and eosinophilic nucleoli at magnification of 400 times
• Grade 3: Clearly visible nucleoli at magnification of 100 times
• Grade 4: Extreme pleomorphism or rhabdoid and/or sarcomatoid morphology

Epidemiology

• CCRCC most commonly affects male patients in their sixties and seventies.
• Majority of cases arise sporadically.
• Only 2–4% of the cases presenting as part of an inherited cancer syndrome, such as von Hippel–Lindau disease.

Notes and References

1. Web site: What is the ISUP/WHO grading system for renal cell carcinoma (RCC)?. Medscape. YiFen Zhang. Updated: Jul 02, 2019
2. Moch. H.. WHO-ISUP-Graduierungssystem für Nierenkarzinome. Der Pathologe. 37. 4. 2016. 355–360. 0172-8113. 10.1007/s00292-016-0171-y.