CT abdomen right anterior cystic renal mass
Figure 1. CT abdomen revealing a large complex 16 x 11 x 12cm right anterior cystic renal mass with a calcified rim abutting the right colon.
A 64-year-old woman underwent a screening colonoscopy at the direction of her primary care physician. The colonoscopy revealed an infiltrative, polypoid, and ulcerated large non-obstructing mass in the mid ascending colon that was biopsy-proven to be a well to moderately differentiated invasive adenocarcinoma.
She underwent staging cross sectional imaging that revealed an incidentally diagnosed 16 cm calcified cystic mass (Bosniak IV) arising from the anterior aspect of an atrophic right kidney abutting the right colon and no evidence of metastatic disease.
On physical examination, she had a palpable mobile right upper quadrant. She elected to proceed with concurrent right open radical nephrectomy and a right hemicolectomy for definitive management. Pathologic evaluation revealed Stage III, pT3N1bMx, G2 colonic adenocarcinoma. Examination of the excised renal mass revealed a cystic hypernephroma of low malignant potential.
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This clinical quiz was prepared by Marc C. Smaldone, MD, MSHP, FACS, of Fox Chase Cancer Center, Philadelphia.
3. Schoots IG, Zaccai K, Hunink MG, et al. Bosniak classification for complex renal cysts reevaluated: A systematic review. J Urol. 2017;198:12-21.
4. Ward RD, Tanaka H, Campbell SC, Remer EM. 2017 AUA renal mass and localized renal cancer guidelines: imaging implications. Radiographics. 2018;38:2021-2033.
Since the introduction of the Bosniak classification system, renal cystic masses are characterized as Bosiak I to IV based on radiographic features of possible malignancy (septa presence and thickness, calcifications, enhancement, solid components, and size) identified on cross sectional imaging (CT, MRI).1 In 1993, the IIF category was introduced to identify lesions with features that warranted short term (3-6 month) imaging surveillance.2 Recent meta-analyses have described a renal cell carcinoma (RCC) incidence of 6%-18%, 51%-55%, and 89%-91% for Bosniak IIF, III, and IV cysts, respectively.3 Based on this correlation, guidelines for managing cystic renal masses have typically recommended surgical excision for Bosniak III and IV lesions (partial nephrectomy preferred when feasible) while close surveillance is recommended for Bosniak IIF lesions.4 However, recent population-based studies have demonstrated that cystic RCC has better cancer-specific survival than solid clear-cell RCC of the same clinical stage, specifically clinical T1b and T2 lesions.5 As a result, experts now suggest active surveillance as an acceptable alternative or even a preferred approach in frail or elderly patients at risk from general anesthesia.6