Login to Access Video or Poster Abstract: MP55-08
Sources of Funding: Funded in part by the Sidney Kimmel Center for Prostate and Urologic Cancers and the National Cancer Institute Training Grant T32 CA082088 (BM, GM)

Introduction

Complex cystic masses pose a clinical challenge given lack of certainty for malignant potential. Cystic changes are common in renal cell carcinoma (RCC); however, there is limited data on cystic RCC (cRCC) specifically. The Bosniak classification system is used to categorize these lesions and help predict risk of malignancy. Current literature suggests that cRCC has a more favorable and benign course, but with no consensus on proper diagnosis and intervention. We aim to better categorize cRCC and the natural history of this disease.

Methods

We identified all patients with pathologically confirmed cRCC, multilocular cRCC, or RCC with cystic features between Jan 2000 - Dec 2015 from our institutional database. Patients with follow-up of <1 year, previous history of RCC, familial syndromes, multifocal tumors, and lesions with >50% solid component on imaging were excluded from our analysis. Available imaging was re-reviewed by a single expert radiologist (AH). Radiological, clinical, and pathological characteristics were recorded.

Results

Of 128 patients identified for analysis, 76 (59.4%) were male and 52 (40.6%) were female. Median age at surgery was 54.4 years (17.3-78.4). Twenty (15.6%) patients had a family history of RCC. The majority of lesions were found incidentally on imaging (89.1%). Fourteen (10.9%) patients had local symptoms, with flank pain (8.6%) being the most common. Partial nephrectomy was performed on 116 (90.6%) patients and radical nephrectomy on 12 (9.4%); open technique was used in >80% of cases. Pathologic and imaging characteristics are shown in Table 1. On median follow-up of 66.1 months, there were no tumor recurrences or metastatic disease. A total of 5 (3.9%) patients died from other conditions.

Conclusions

Diagnosis of cRCC should include cystic lesions with <50% solid component on imaging. Our data shows that cRCC includes a wide variety of tumors, most commonly with clear cell features. Most of these lesions are discovered incidentally on imaging as Bosniak grades 3 or 4 and are surgically resected. These patients uniformly do well with minimal risk of recurrence or metastasis on follow-up, thus, nephron sparing surgery is recommended. Given the indolent nature cRCC, enrollment of these patients into active surveillance protocols should be considered.

Funding

Funded in part by the Sidney Kimmel Center for Prostate and Urologic Cancers and the National Cancer Institute Training Grant T32 CA082088 (BM, GM)