Solitary solid renal mass: can we predict malignancy?

Abstract

Study Type – Therapy (retrospective cohort) Level of Evidence 3a What's known on the subject? and What does the study add? It is known that the majority (80%) of solid renal masses are malignant. Most of the literature suggests that smaller tumour size is associated with a higher incidence of benign disease. We have confirmed that decreased tumour size is associated with benign disease, particularly for lesions <2 cm. Once radiologically apparent angiomyolipomas are excluded, the incidence of benign disease with small renal masses is lower than reported in the literature (11%). Furthermore, we have shown that small renal masses in females have a higher association with benign disease. Patient age and tumour location were not predictive of benign histology. We have also stratified our risks not only for benign disease but also for clinically indolent renal cancers to help physicians counsel patients with regard to managing these solid renal masses. OBJECTIVE To determine the clinical predictors of benign disease in patients with solitary solid renal masses. PATIENTS AND METHODS Pathology reports of patients who underwent radical or partial nephrectomy at two hospitals from 1998 to 2008 were reviewed. Only patients with solitary solid unilateral renal masses were included. Predictors of malignancy risk were assessed with univariate and multivariate logistic regression analysis. RESULTS A total of 592 patients with a mean (sd) age of 60 (13) years were included, 38% of whom were women. Radical and partial nephrectomy was performed in 66% and 34% of patients, respectively. Renal masses were equally distributed on the right and left sides (49% vs 51%, P= 0.84). Masses were more commonly located in the upper and lower poles than in the mid pole (40.8% vs 38.7% vs 20.5%, respectively). The mean tumour size was larger in patients who underwent radical compared with partial nephrectomy (6.8 cm vs 2.9 cm, P < 0.001). The rate of benign disease in our overall population was 9.5%. On univariate and multivariate analysis, only a renal mass size <2 cm and female gender were predictive of benign disease. On further analysis the magnitude of this effect was found to be additive. CONCLUSIONS Renal masses <2 cm and female gender were associated with a higher probability of benign disease. Patient age and tumour location were not predictive of benign disease.

Angiomyolipoma (AML) without visible fat: Ultrasound, CT and MR imaging features with pathological correlation

“…These AML are considered indistinguishable from other renal masses, requiring percutaneous biopsy or surgery for diagnosis. AML with no detectable fat represent the most commonly resected benign renal mass in surgical series [6,7].…”

Evaluation of T1-Weighted MRI to Detect Intratumoral Hemorrhage Within Papillary Renal Cell Carcinoma as a Feature Differentiating From Angiomyolipoma Without Visible Fat

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AMLs without visible fat are commonly resected benign renal neoplasms [7,8]; therefore, preoperative differentiation of AML without visible fat from renal cell carcinoma (RCC) is desirable.Numerous CT and MRI findings associated with AML without visible fat have been reported [4,6,[9][10][11][12][13][14][15][16][17][18][19]. Of these findings, low T2-weighted signal intensity (SI) is a characteristic finding because of the abundant smooth muscle content of AML without visible fat [5,6,17,20,21].

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“…AMLs without visible fat are commonly resected benign renal neoplasms [7,8]; therefore, preoperative differentiation of AML without visible fat from renal cell carcinoma (RCC) is desirable.…”

Defining the Added Value of 99mTc-MIBI SPECT/CT to Conventional Cross-Sectional Imaging in the Characterization of Enhancing Solid Renal Masses

“…5,11,12 A potentially aggressive histology, such as the clear cell subtype of RCC, is observed in about 50% of enhancing clinical stage T1 renal tumors. 4 Histologically, oncocytomas are composed of round cells with mitochondria-rich eosinophilic cytoplasm. 4 Histologically, oncocytomas are composed of round cells with mitochondria-rich eosinophilic cytoplasm.…”