Although there have been several pathological studies of CCPRCT, few studies have focused on the patient's clinical and surgical outcomes. In this study, most patients were discovered incidentally, but about 10% complained of nonspecific flank pain and abdominal pain. Similar results have been found in other studies [8]. However, the diameter of the largest mass is 4.1 cm, and the median diameter of mass is 1.2 cm. It is difficult to prove a clear causal relationship between pain and masses. Although it is known that there is no difference according to gender, the proportion of men in this study was about 70% [11].
Initially, CCPRCT was thought to occur only in ESRD. However, several studies have reported that CCPRCT also occurs in patients without ESRD [12, 13]. Only about 20% of the patients in this study had ESRD as a comorbidity. CCPRCT may present as multiple bilateral disease, and VHL syndrome may require differential diagnosis. CCPRCT has been described in a patient with VHL syndrome [14]. In this study, one patient had VHL syndrome and had a history of contralateral metachronous ccRCC.
Among cases of nephrectomy, CCPRCT accounted for 1.8%. The prevalence of CCPRCT is known to be about 1–4% [8], and it is judged that similar results could be obtained in this cohort even if patients who only undergo actual biopsy and have not undergone surgery are included. CCPRCT has rarely been reported as a metastatic or advanced disease to date [8, 15–17]. There were no advanced stages in this study, too. Therefore, if CCPRCT can be predicted in advance, not only partial nephrectomy but also minimally invasive treatment such as ablation or active surveillance can be considered as treatment options. However, it is not easy to clearly distinguish between CCPRCT and small renal mass with the other histologic subtype on CT or magnetic resonance imaging [18]. If there is no significant change in the image during the follow-up period, it would be a good strategy to establish a treatment plan after confirming the pathology through a biopsy [19].
CCPRCT is mostly small, with an average size reported of about 2 cm. It is usually surrounded by a well-defined, thin fibrocystic mass, and most cases are solitary tumors. However, sometimes multiple or bilateral tumors have been reported [20, 21]. Multiple and bilateral masses were also reported in this study. In histopathology, CCPRCT consists of variable architectures of solid, cystic and papillary patterns. In immunohistochemistry, it is positive for carbonic anhydrase IX, CK7, and high molecular weight cytokertin, and negative for AMACR, CD10, and TFE3 [7]. Based on these characteristics, ccRCC, papillary RCC, Xp11 translocation RCC, MiT family translocation-associated RCC, and RCC with smooth muscle stroma should be considered as differential diagnoses [22, 23].
This study is significant in that it summarized and described the clinical and preoperative data of CCPRCT patients from the clinician's point of view. Being able to have an understanding of and impression of pathological features or clinical outcomes of CCPRCT will help develop beneficial treatment plans for patients. In particular, the strength of this study is that it provided surgical information on these pathological results by describing the results of partial nephrectomy at CCPRCT.
This study has some limitations. First, it is retrospective, single-center data, and it did not include a large number of patients. Therefore, the results of our study must be confirmed and validated with a prospective large-scale multi-center study. However, the cohort used in this study is prospectively collected data and it is judged to have less bias than the original retrospective study. Furthermore, although it was meaningful in characterizing and describing CCPRCT, it could not predict preoperative CCPRCT. There was no significant difference on imaging, and the symptoms complained of by the patient were not clear. It was thought that further study was needed to predict CCPRCT using magnetic resonance imaging or contrast enhanced ultrasonography.