目的:分析肿瘤最大径≤4 cm的小肾细胞癌患者的临床与病理特征,进一步了解其发生特点及影响术后复发、进展的因素。方法:采用分层抽样法选择肾细胞癌患者200例进行回顾性分析,收集患者的一般状况、肿瘤特征、肾细胞癌病灶的病理特征(含镜下特征)。按肾肿瘤病灶最大径将患者分组,使用单因素分析比较各组间患者肿瘤分期、分级与镜下病理特征间的差异,采用二元多因素Logistic回归方法分析小肾细胞癌患者肿瘤进展及与预后相关的因素。结果:200例肾细胞癌患者中127例患者的肿瘤最大径≤4 cm,病理亚型以肾透明细胞癌为主。随着肿瘤最大径增加,患者出现更高的T分期(P<0.01)、更高的WHO/国际泌尿病理学会(International Society of Urological Pathology,ISUP)分级(P<0.05), 淋巴结转移概率显著升高(P<0.01)。肿瘤最大径≤4 cm时,患者也可出现肿瘤侵犯肾周脂肪、肾窦,肿瘤分级升高(≥3级)及同时性肺转移。肿瘤最大径>4 cm且≤7 cm的肾细胞癌患者出现脉管内癌栓(9.3% vs. 0)、肿瘤坏死(27.8% vs. 5.5%)的比例显著高于肿瘤最大径≤4 cm的患者(P<0.01)。以肿瘤最大径2 cm作为分界点对小肾细胞癌患者行亚组分析,最大径>2 cm且≤4 cm的肿瘤与最大径≤2 cm的肿瘤相比,出现肿瘤内出血(44.7% vs. 23%,P<0.05)、坏死(8.2% vs. 0,P=0.095)的患者更多。Logistic回归分析提示,透明细胞癌出现肿瘤侵犯肾被膜的概率高于其他亚型小肾细胞癌(OR=5.15,95%CI:1.36~19.52), 肿瘤内部坏死的小肾细胞癌周围更有可能出现假包膜(OR=14.90,95%CI:1.41~157.50),肿瘤最大径增加会使出现高级别(≥3级)肾细胞癌的概率增加(OR=3.49,95%CI:1.11~10.93)。结论:小肾细胞癌(≤4 cm)整体病理分期、分级较低,但可能出现肾外侵犯及同时性远处转移(synchronous metastasis)现象。肿瘤内部出血、坏死,组织学亚型为透明细胞癌的肿瘤可能影响肿瘤侵犯肾被膜、肿瘤周围出现假包膜等病理特征的发生概率,可以作为进一步区分小肾细胞癌肿瘤学行为、评估预后的因素。

Objective: To analyze the clinical and pathological features of small renal cell carcinoma (RCC), especially of those with diameter less than 4 cm and to understand the characteristics and factors related to recurrence and progression.Methods: A total of 200 patients with RCC were stratifiedly selected for retrospective analysis. Their baseline demographic features, tumor-specific clinical features, pathological features of renal lesions, especially microscopic features were collected. The patients were divided according to the largest diameter of renal tumor lesions. Univariate analysis was used to compare the differences between tumor staging and microscopic pathological features between the groups. Binary multivariate Logistic regression was used to investigate factors related to tumor progression and prognosis in the patients with small RCC.Results: The tumor diameters of 127 RCC patients were less than 4 cm and most of them had clear cell renal cell carcinoma (ccRCC). The increase in tumor diameter resulted in significantly higher T stage (P<0.01), higher WHO/International Society of Urological Pathology (ISUP) grade (P<0.05) and increasing chance of lymph node metastasis (P<0.01). Even when the tumor diameter was less than 4 cm, the patients might still have perirenal fat invasion, renal sinus invasion and greater elevated tumor grade (greater than grade 3) and synchronous lung metastasis. The incidences of intravascular thrombus (9.3% vs. 0) and tumor necrosis (27.8% vs. 5.5%) in the patients with RCC between 4-7 cm were significantly higher than those with RCC less than 4 cm (P<0.01). Sub-group analysis of small RCC (less than 4 cm) indicated that the patients with RCC between 2-4 cm were more likely to have intratumoral hemorrhage (44.7% vs. 23%, P<0.05) and necrosis than those with RCC less than 2 cm (8.2% vs. 0, P=0.095). Logistic regression analysis of small RCC showed that the incidence of tumor invasion to renal capsule was higher in ccRCC (OR=5.15, 95%CI: 1.36-19.52). Necrosis was closely related to the formation of peritumor pseudocapsule in small RCC (OR=14.90, 95%CI: 1.41-157.50). Increase in the tumor diameter was related to higher tumor grade (greater than grade 3) (OR=3.49, 95%CI: 1.11-10.93).Conclusion: The tumor stage and grade of small RCC (less than 4 cm) are low, but extra-renal invasion and synchronous distant metastasis may occur. Internal hemorrhage and necrosis in tumor, ccRCC subtype, along with microscopic features, such as the renal capsule invasion and perirenal pseudocapsule formation are relevant factors of malignant behavior of small RCC and could be considered in prognosis evaluation.