Acceptance of emerging renal oncocytic neoplasms: a survey of urologic pathologists

Abstract

Oncocytic renal neoplasms are a major source of diagnostic challenge in genitourinary pathology; however, they are typically nonaggressive in general, raising the question of whether distinguishing different subtypes, including emerging entities, is necessary. Emerging entities recently described include eosinophilic solid and cystic renal cell carcinoma (ESC RCC), low-grade oncocytic tumor (LOT), eosinophilic vacuolated tumor (EVT), and papillary renal neoplasm with reverse polarity (PRNRP). A survey was shared among 65 urologic pathologists using SurveyMonkey.com (Survey Monkey, Santa Clara, CA, USA). De-identified and anonymized respondent data were analyzed. Sixty-three participants completed the survey and contributed to the study. Participants were from Asia (n = 21; 35%), North America (n = 31; 52%), Europe (n = 6; 10%), and Australia (n = 2; 3%). Half encounter oncocytic renal neoplasms that are difficult to classify monthly or more frequently. Most (70%) indicated that there is enough evidence to consider ESC RCC as a distinct entity now, whereas there was less certainty for LOT (27%), EVT (29%), and PRNRP (37%). However, when combining the responses for sufficient evidence currently and likely in the future, LOT and EVT yielded > 70% and > 60% for PRNRP. Most (60%) would not render an outright diagnosis of oncocytoma on needle core biopsy. There was a dichotomy in the routine use of immunohistochemistry (IHC) in the evaluation of oncocytoma (yes = 52%; no = 48%). The most utilized IHC markers included keratin 7 and 20, KIT, AMACR, PAX8, CA9, melan A, succinate dehydrogenase (SDH)B, and fumarate hydratase (FH). Genetic techniques used included TSC1/TSC2/MTOR (67%) or TFE3 (74%) genes and pathways; however, the majority reported using these very rarely. Only 40% have encountered low-grade oncocytic renal neoplasms that are deficient for FH. Increasing experience with the spectrum of oncocytic renal neoplasms will likely yield further insights into the most appropriate work-up, classification, and clinical management for these entities.

Keywords: Emerging; Eosinophilic; Oncocytic; Renal neoplasms; Uropathologists.

Fig. 1

Bar graph depicting the immunohistochemical stains of choice used by the survey participants in the differential diagnosis of eosinophilic renal tumors

Fig. 2

An example of eosinophilic solid and cystic renal cell carcinoma: (A, B) this tumor is characterized by an admixture of solid and cystic architecture, eosinophilic cytoplasm, with coarsely granular, basophilic cytoplasmic stippling, and focal to diffuse immunoreactivity for keratin 20 (C)

Fig. 3

An example of low-grade oncocytic tumor: A loose cells interconnect with each other in an end-to-end distribution rather than round nests as seen in oncocytoma; B other areas show solid growth with round to oval nuclei, and a lack of “raisinoid” nuclei; C staining for keratin 7 is diffuse; D GATA3 is positive

Fig. 4

An example of papillary renal neoplasm with reverse polarity: A thin arborizing papillary architecture with hyalinized papillae. The lining cells are cuboidal with eosinophilic finely granular cytoplasm containing apically located low-grade nuclei opposite to the basement membrane; B the tumor exhibited strong and diffuse nuclear expression for GATA3

Fig. 5

A flowchart shows a potential algorithm for discriminating eosinophilic renal tumors, with emphasis on emerging subtypes. Abbreviations: RCC, renal cell carcinoma; EVT, eosinophilic vacuolated tumor; LOT, low-grade oncocytic tumor; ESC, eosinophilic solid and cystic; PRNRP, papillary renal neoplasm with reverse polarity; NOS, not otherwise specified. *Not all features are present in every tumor