Purpose: It was previously thought that renal cell carcinoma with a diameter of 3 cm or less has low potential to cause distant metastasis. However, metastasis develops in a small number of cases, which cannot be ignored. We investigated the clinicopathological characters of small renal cell carcinoma with metastasis to further understand this condition.
Materials and methods: From January 1983 to February 2009, 165 cases of sporadic renal cell carcinoma 3 cm or less were treated at our department. Bilateral and von Hippel-Lindau disease were excluded from study. Clinicopathological parameters and outcome data were collected on each patient and analyzed.
Results: Histologically the 165 cases of primary renal cell carcinoma 3 cm or less included 151 of clear cell, 10 of papillary and 4 of chromophobe renal cell carcinoma, of which 4 had sarcomatoid differentiation, 6 had perinephric and/or sinus invasion and 20 had microvascular invasion. Overall we identified 10 metastatic cases (6.06%), of which 5 were synchronous. Univariate analysis revealed that age 60 years or greater (p = 0.0139), symptoms (p = 0.0054) and microvascular invasion (p <0.0001) were significant risk factors. Multivariate analysis showed that only microvascular invasion was a significant risk factor (p = 0.00062). Perinephric and/or sinus fat invasion was not a significant risk factor.
Conclusions: Metastasis also develops in small renal cell carcinoma cases. Results suggest that microvascular invasion is a significant risk factor and patients with microvascular invasion should be followed more carefully.
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