Clear Cell Papillary Renal Cell Carcinoma: New Clinical and Imaging Characteristics

Abstract

To investigate clear cell papillary (CCP) renal cell carcinoma (RCC), an uncommon tumor of low malignant potential characterized by low-grade, clear cells, showing papillary and tubular architecture. This relatively newly described entity is still being characterized. We present our series of CCP RCC with new clinical and imaging findings. We reviewed the clinical, pathologic, and imaging findings of 28 CCP RCCs in 21 patients identified from our institution between 2010 and 2016. Sixteen of 21 (76%) patients were African American with an equal male-to-female ratio. Mean follow-up was 26.1 ± 16.9 months. Mean age at diagnosis was 58.3 ± 10.7 years, and mean preoperative creatinine was 2.7 ± 2.9 mg/dL. End-stage renal disease or chronic kidney disease was present in 10 of 21 (47.6%) patients. Mean tumor size was 2.2 ± 1.5 cm. All cases were stage pT1, and 25 of 28 (89%) tumors were grade 2. No necrosis or sarcomatoid features were identified. Two patients had synchronous clear cell RCC and 1 patient had synchronous papillary RCC. No recurrence or metastases were identified. On imaging, the majority of the lesions were solid, with relatively low-level enhancement, similar to papillary RCC, with regions of heterogeneous hyper-enhancement, similar to clear cell RCC. The rate of growth on serial imaging was comparable with that observed for other low-staged RCCs. In our series, CCP RCC was seen more commonly in African American patients and associated with end-stage renal disease or chronic kidney disease. Imaging characteristics are similar in both clear cell RCC and papillary RCC. A nephron-sparing approach is recommended when surgically feasible.