Evaluation of Bosniak category IIF complex renal cysts

Abstract

PurposeTo evaluate moderately complex renal cysts of Bosniak category IIF.Materials and methodsThe regional ethics committee approved the study. In the period 2003–2009, radiological CT reports of 8,402 CT examinations of the kidneys were analysed retrospectively by one radiologist. All complex cystic lesions in the kidney (n = 550 in the same number of patients) were reclassified according to the Bosniak classification by two radiologists in consensus. If a patient had more than one lesion, only the highest Bosniak category was recorded. All Bosniak IIF lesions with ≥2-year follow-up were included in the study.ResultsThirty-two Bosniak IIF lesions were found. Five lesions (16 %) were upgraded during follow-up and the patients were offered surgery. Pathology of three lesions showed papillary carcinoma, clear cell renal carcinoma and chronic inflammation, respectively. Due to comorbidity the remaining two patients were followed with CT without intervention. Ten lesions (31 %) with follow-up periods >5 years had no further radiological changes and clinical follow-up was stopped.ConclusionThe use of Bosniak category IIF is clinically applicable, resulting in an overall surgical nephron-sparing approach to complex renal cysts.Teaching Points• The Bosniak classification is used to categorise complex renal cystic masses• BIIF cysts behave mostly as benign lesions• Radiological progression in complexity occurs in only 16 % of cases• BIIF category seems promising for clinical application, potentially avoiding unnecessary surgery

CUA guideline on the management of cystic renal lesions

“…Large hyperdense cysts (≥3 cm and >20 HU) also belong to this group. [20][21][22] Any lesions not fulfilling the criteria for category II, but not as complex as category III should be classified in this category.…”

“…(Level of evidence: 3; Recommendation: B) Approximately 15% of these category IIF cysts will progress in complexity (to Bosniak category III or IV) over time. 7,13,20,21,36 Progression is more likely to occur within the first two years and rarely occurs after five years. 36 Unfortunately, a clear progression pattern is yet to be identified and as a result, there is no evidence-based time limit for followup imaging.…”

Surveillance and clinical outcome of bosniak IIF renal cysts: a mini review

“…Surprisingly, the malignancy risk in the BII classification remains unsatisfactorily elevated (12%), even in the procedure reported after BIIF was incorporated. 29 The malignancy rate of 54% differs from the malignancy rate of 82% in 33 Bosniak III resections recorded by O'Malley et al 7 The high incidence of malignancy was because of the adoption of more established examinations.…”

Bilaterally enlarged adrenal glands without obvious cause: need for a multidisciplinary diagnostic work‐up

“…CT scan of patient 3 showing metastatic disease with multiple hepatic lesions, enlargement of both adrenal glands (left 15.3 × 10.0 × 15.6 cm (arrow), right approximately 5 cm; a), and a Bosniak 2F lesion in the right kidney (arrow b). Bosniak 2F lesions are generally benign, with a malignancy rate of 3–12% .…”