Emerging and Recently Described Subtypes of Renal Carcinoma

Abstract

Several new subtypes of renal carcinoma have been described in recent years and represent a growing awareness of the subtleties of renal cancer morphology and their relationship to molecular alterations. One example of this encompasses Xp11 translocation carcinomas, described in Chap. 7, where distinct molecular changes impact both morphological variation and prognosis. Several other nonconventional subtypes of renal cell carcinoma have been incorporated into standard classification schema for renal neoplasia, although some entities still require further study and are considered “emerging entities” (Srigley et al., Am J Surg Pathol, 2013; 37(10):1469–89). Although our knowledge surrounding these neoplasms continues to expand, it appears that at least some of these lesions are associated with distinct molecular alterations and clinical behavior. Given that many of these entities have only been recently described, there is limited knowledge about therapies that may be uniquely applied to these entities.

The response of these new histologic subtypes to therapy has not been systematically studied. Treatment guidelines generally use the WHO histologic classification system, which includes clear cell, papillary, and chromophobe histology (Eble et al., Pathology and genetics of tumours of the urinary system and male genital organs. Lyon, IARC, 2004). The most widely used clinical guidelines, the NCCN guidelines, separate treatments by “predominantly clear cell histology” vs. “predominantly non-clear cell histology” (Motzer et al., J Natl Compr Canc Netw, 2015; 13(2):151–9) and then also categorize treatments by prognostic group using validated prognostication systems such as the Motzer criteria (Motzer et al., N Engl J Med, 2007; 356(2):115–24). The prognosis and response of these new histologic subtypes to systemic therapies awaits further study.