Cases
Man in his late forties with left renal mass    

Discussion

Renal cell carcinoma with leiomyomatous stroma

Renal cell carcinoma accounts for approximately 3% of all cancer cases in adults, and 90% to 95% of kidney neoplasms. It is also more common in males than in females (2:1), and rare in children. Clear cell renal cell carcinomas accounts for 65% to 75% of all malignant renal tumors.

Renal cell carcinoma with leiomyomatous stroma is a rare entity that is thought to be distinct from clear cell renal carcinoma, although research is ongoing. So far, no gender predominance has been found; the right kidney is affected as commonly as left.

Renal cell carcinomas with leiomyomatous stroma are well-circumscribed tumors. The cut surface is typically gray-white fibrotic tissues composed of small nests and nodules of renal epithelial cells with clear cytoplasms. Carcinoma cells are embedded in a cellular stroma comprising intertwining bundles of smooth muscle. The leiomyomatous stromal component is proposed to be polyclonal and therefore reactive, rather than neoplastic. It is hypothesized to be derived from smooth muscle cells of large-caliber veins located at the peripheral capsular region or within the collagenous septae of the tumors. IHC is typically positive for CK7 and CD10, as well as CAIX, pankeratin, vimentin, and HIF1-alpha. The prognosis is generally good, with a low rate of tumor recurrence.

Differential diagnostic methods for renal clear cell carcinoma include FISH, gene sequencing, and methylation-specific multiplex ligation-dependent probe amplification analysis; renal clear cell carcinoma will show deletion of chromosome 3p, VHL mutation, and VHL methylation abnormalities. Additional differential diagnostic methods may include genetic testing, as renal cell carcinomas with leiomyomatous stroma show recurrent mutations of TSC1/TSC2, MTOR, and/or ELOC, consistent with hyperactive MTOR complex.

References

  1. Yeh YA, Constantinescu M, Chaudoir C, et al. Renal cell carcinoma with leiomyomatous stroma: A review of an emerging entity distinct from clear cell conventional renal cell carcinoma. Am J Clin Exp Urol. 2019 Oct 15;7(5):321-326. PMID: 31763363; PMCID: PMC6872474.
  2. Kiremit MC, Acar Ö, Sağlıcan Y, Esen T. Bilateral renal cell carcinoma with leiomyomatous stroma: A rare entity diagnosed synchronously and treated surgically in a staged fashion. Turk J Urol. 2017 Dec;43(4):566-570. doi: 10.5152/tud.2017.68639. Epub 2017 Dec 1. PMID: 29201528; PMCID: PMC5687228.
  3. Shah RB, Stohr BA, Tu ZJ, et al. "Renal cell carcinoma with leiomyomatous stroma" harbor somatic mutations of TSC1, TSC2, MTOR, and/or ELOC (TCEB1): Clinicopathologic and molecular characterization of 18 sporadic tumors supports a distinct entity. Am J Surg Pathol. 2020 May;44(5):571-581. doi: 10.1097/PAS.0000000000001422. PMID: 31850909.
  4. Petersson F, Branzovsky J, Martinek P, et al. The leiomyomatous stroma in renal cell carcinomas is polyclonal and not part of the neoplastic process. Virchows Arch. 2014 Jul;465(1):89-96. doi: 10.1007/s00428-014-1591-9. Epub 2014 May 18. PMID: 24838683.
  5. Martignoni G, Brunelli M, Segala D, et al. Renal cell carcinoma with smooth muscle stroma lacks chromosome 3p and VHL alterations. Mod Pathol. 2014 May;27(5):765-74. doi: 10.1038/modpathol.2013.180. Epub 2013 Nov 8. PMID: 24201123.
  6. Peckova K, Grossmann P, Bulimbasic S, et al. Renal cell carcinoma with leiomyomatous stroma--further immunohistochemical and molecular genetic characteristics of unusual entity. Ann Diagn Pathol. 2014 Oct;18(5):291-6. doi: 10.1016/j.anndiagpath.2014.08.004. Epub 2014 Aug 15. PMID: 25175809.