Histologic Heterogeneity of Extirpated Renal Cell Carcinoma Specimens: Implications for Renal Mass Biopsy

Pathologic characteristics of extirpated renal cell carcinoma (RCC) specimens <7 cm were reviewed to get better information on technical nuances of renal mass biopsy (RMB). Specimens were stratified according to tumor stage, nuclear grade, size, histology, presence of lymphovascular invasion (LVI), necrosis, and sarcomatoid features. When considering pT1 (0–7 cm) tumors, pT1b (4–7 cm) RCC masses were more likely to have necrosis (43% vs 16%, P < 0.001), LVI (6% vs 2%, P = 0.024), high-grade nuclear elements (29% vs 17%, P < 0.001), and sarcomatoid features (2% vs 0%, P = 0.006) compared with pT1a (0–4 cm) tumors. Additionally, pT3a tumors were more highly associated with necrosis (P = 0.005), LVI, sarcomatoid features, and high-grade disease (P for all < 0.001) when compared to pT1 masses. For masses <4 cm, pT3a cancers were more likely to demonstrate necrosis (38% vs 16%, P < 0.001), LVI (22% vs 2%, P < 0.001), high-grade nuclear elements (45% vs 17%, P < 0.001), and sarcomatoid features (12% vs 0%, P < 0.001) compared to pT1a tumors. Similarly, for masses 4–7 cm, pathologic T3a tumors were significantly more likely to have sarcomatoid features (12% vs 2%, P = 0.006) and LVI (22% vs 6%, P = 0.003) compared to pT1b tumors. In summary, pT3a tumors and those RCC masses >4 cm exhibit considerable histologic heterogeneity and may harbor elements that are not easily appreciated with limited renal sampling. Therefore, if RMB is considered for renal masses greater than 4 cm or those that abut sinus fat, a multi-quadrant biopsy approach is necessary to ensure adequate sampling and characterization of the mass.

The role of renal biopsy to improve small renal mass diagnosis and management: are there predictive factors for a higher detection rate? The first Italian study of 100 cases

BACKGROUND

Incidence of small renal masses (SRMs) has increased over the last decade: in order to reduce overtreatment of benign lesions, renal tumor biopsy (RTB) has been advocated. The primary aim of this study were to establish the rate of diagnostic biopsies and the concordance rate between RTB and surgical pathology with regard to tumor histology. The secondary aim was to identify what predictive factors are associated with an initial diagnostic biopsy.

METHODS

We retrospectively analyzed RTB performed in our center in patients with SRMs between 2015 and 2017. We assessed patient demographics and clinical status, lesion characteristics and procedural factors. The categorical variables were tested with the chi-square test. We used univariate and multivariate analysis to identify what factors are indicative of non-diagnostic biopsies. We used the SPSS statistics v. 23.

RESULTS

We performed a total of 100 RTBs to management 94 patients. The initial biopsy was diagnostic in 88 patients (67 malignant and 21 benign lesion). The six remaining patients had repeat biopsies, of which four were diagnostic. Complications rate was 5% prevalently local hematoma treated with surveillance. Agreement between biopsy and surgical histology was found in 94% of cases. On contingency analysis and on univariate and multivariate analysis, these factors (age, tumor size, exophytic location, and type of imaging used) were not predictive with diagnostic biopsy.

CONCLUSIONS

RTB for SRMs helps establish pre-treatment diagnosis, reduce overtreatment, with a low risk of complications and high diagnostic rate. In our experience, we did not find predictive factors more likely associated with a diagnostic biopsy.

Categorizing renal oncocytic neoplasms on core needle biopsy: a morphologic and immunophenotypic study of 144 cases with clinical follow-up. Alderman MA, Daignault S, Wolf JS Jr, Palapattu GS, Weizer AZ, Hafez KS, Kunju LP, Wu AJ. Hum Pathol.September 2016;55:1-10

There is limited literature on renal oncocytic neoplasms diagnosed on core biopsy. All renal oncocytic neoplasm core biopsies from 2006 to 2013 were, retrospectively, reviewed. Morphologic features and an immunohistochemical panel of CK7, c-KIT, and S100A1 were assessed. Concordance with resection diagnosis, statistical analysis including a random forest classification, and follow-up were recorded. The postimmunohistochemical diagnoses of 144 renal oncocytic core biopsies were favor oncocytoma (67%), favor renal cell carcinoma (RCC) (12%), and cannot exclude RCC (21%). Diagnosis was revised following immunohistochemistry in 7% of cases. The most common features for oncocytoma (excluding dense granular cytoplasm) were nested architecture, edematous stroma, binucleation and tubular architecture; the most common features for favor RCC were sheet-like architecture, nuclear pleomorphism, papillary architecture, and prominent cell borders. High nuclear grade, necrosis, extensive papillary architecture, raisinoid nuclei, and frequent mitoses were not seen in oncocytomas. Comparing the pathologist and random forest classification, the overall out-of-bag estimate of classification error dropped from 23% to 13% when favor RCC and cannot exclude RCC was combined into 1 category. Resection was performed in 19% (28 cases) with a 94% concordance (100% of favor RCC biopsies and 90% of cannot exclude RCC biopsies confirmed as RCC; 83% of favor oncocytomas confirmed); ablation in 23%; and surveillance in 46%. Follow-up was available in 92% (median follow-up, 33 months) with no adverse outcomes. Renal oncocytic neoplasms comprise a significant subset (16%) of all core biopsies, and the majority (78%) can be classified as favor oncocytoma or favor RCC.

Current Role of Renal Biopsy in Urologic Practice

Most small renal masses (SRMs) are indolent. In fact, only approximately 80% of SRMs are malignant. Furthermore, SRMs are commonly detected in elderly and comorbid patients. Therefore, opportunities for better care intensity calibration exist. Renal mass biopsy (RMB), when appropriately used, is a valuable clinical tool to help with critical clinical decision-making in patients with SRM. This article summarizes the role of modern RMB in helping gauge care for patients with SRM.