Mucinous tubular and spindle cell carcinomas of the kidney (MTSCC-Ks): CT and MR imaging characteristics

To strengthen the recognition of mucinous tubular and spindle cell carcinomas of the kidney (MTSCC-Ks) by analyzing CT and MR imaging findings of MTSCC-Ks.This study retrospectively enrolled ten patients with pathologically confirmed MTSCC-Ks from 2007 to 2020. The main observed imaging characteristics included growth pattern, signal characteristics on T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), hemorrhage, necrosis, cystic degeneration, lipid component, pseudocapsule and the enhancement pattern. Apparent diffusion coefficient (ADC) value of MTSCC-Ks and normal renal cortex were measured, respectively. All imaging features were evaluated in consensus by two genitourinary radiologists.All patients (53.1 ± 6.5 years, male to female, 3:7) presented with a solitary renal tumor with the mean diameter of 3.5 ± 0.4 cm. All lesions showed iso- or slight hypoattenuation on non-contrast CT with no hemorrhage but cystic degeneration (10%) and necrosis (10%). On T2WI, all lesions showed predominantly slight hypointensity with focal hyperintensity. The ADC value of MTSCC-Ks was 0.845 ± 0.017 × 10-3 mm2/s, and ADCtumor-to-ADCrenal cortex value was 0.376 ± 0.084. Pseudocapsules existed in all MTSCC-Ks on MRI. There were seven lesions showed heterogeneous enhancement, while three lesions showed homogeneous enhancement. Among them, six MTSCC-Ks showed slight multiple patchy enhancement (60%) in the corticomedullary phase, while the remaining MTSCC-Ks showed homogeneously slight enhancement (30%) or slightly stratified enhancement (10%). All MTSCC-Ks exhibited slow and progressive enhancement in the late phases.Iso- or slight hypoattenuation on CT, slight hypointensity with focal hyperintensity on T2WI, marked diffusion restriction on DWI and ADC map, slight multiple patchy enhancement in the corticomedullary phase, and slow and progressive enhancement in the late phases are the imaging features of MTSCC-Ks, which may facilitate the diagnosis of MTSCC-Ks.