Differences in clinical and computed tomography imaging features between two types of mixed epithelial and stromal tumor of the kidney: Suggestions for patient management

Background: To analyze the differences in clinical features and computed tomography characteristics in the two types of mixed epithelial and stromal tumor of the kidney (MESTK) and to establish a treatment plan for the MESTK types. Methods: 17 patients underwent multidetector computed tomography (MDCT) before surgery and had a pathological diagnosis of MESTK were enrolled. Their clinical information (R.E.N.A.L.Nephrometry Score (R.E.N.A.L.－NS), radical nephrectomy (RN), partial nephrectomy (PN), etc.) were collected. The radiological features included renal sinus fat invagination (SFI), maximal diameter (MD), capsule and septa of the tumor, etc. were also analyzed. They were divided into two types according to the MD solid /MD tumor ratio (type A with > 63%; type B with ≤ 63%). An independent-sample t-test and Fisher exact test were used to assess the differences between the two groups. Results: MESTKs demonstrated a variable multi-septate cystic and solid components with a delayed enhancement. There were 9 patients for type A and 8 subjects for type B. Compared with type A, the lesions in type B have larger MD (79.13±39.06 vs. 41.22±24.19, p = 0.028), higher R.E.N.A.L.－NS (10.03±0.50 vs. 8.95±1.26, P＜0.001), higher RN (75.00% vs.22.22%, p =0.015), larger SFI (87.5% vs.33.3%, p=0.05), more septa (100% vs. 0%, p <0.001) and more capsule (100% vs. 11.1%, p < 0.001). Conclusion: Type B MESTK has more hazardous features compared with type A, suggesting that RN is more suitable for type B and PN for type A.