Mucinous Tubular and Spindle Cell Carcinoma of the Kidney: A Study of Clinical, Imaging Features and Treatment Outcomes

Abstract

PurposeTo describe the clinical, imaging, pathological features and oncologic outcomes of mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney.Patients and MethodsTwenty-two cases of MTSCC were pathologically identified between January 2004 and April 2021 at our institution. The clinical and imaging findings, pathological features, treatment methods and outcomes of the patients were reviewed.ResultsThese cases included 17 women and 5 men, with a median age at diagnosis of 52.5 years. On contrast-enhanced CT, MTSCC was less enhanced than the adjacent renal parenchyma. Tumor attenuation values were 33.3 ± 6.8HU, 44.0 ± 9.1HU, 54.4 ± 13.9HU and 67.1 ± 11.8HU in the non-contrast, corticomedullary, nephrographic and excretory phases of CT, respectively. Contrast-enhanced ultrasonography and MRI also showed hypovascular features of the masses. On MRI, the tumors were isointense on T1-weighted images and slightly hypo- or hyperintense on T2-weighted images. Diffusion-weighted imaging revealed a low apparent diffusion coefficient of the tumor. The patients were managed with laparoscopic partial nephrectomy (n=5), radical nephrectomy (n=16), or robotic-assisted laparoscopic partial nephrectomy (n=1). The median follow-up time was 59.5 months. All the patients were free of local recurrence or distant metastasis.ConclusionsMTSCC is generally indolent and has favorable outcomes. The imaging features of MTSCC are generally hypovascular, which is significantly different from clear cell renal cell carcinoma. However, it is still difficult to distinguish MTSCC from other hypovascular renal tumors preoperatively because their imaging features overlap. Further studies are essential to fully characterize the features of this rare RCC variant.

Mucinous tubular and spindle cell carcinoma of the kidney: a report of seven cases

“…In the present case series, none of the seven patients with MTSCC had metastases. Details are as follows: three patients were diagnosed with pT1aN0M0 (42.9%), two with pT1bN0M0 (28.5%), one with pT2bN0M0 (14.3%) and one with pT3bN0M0 stage with tumour thrombus in the inferior vena cava and left renal vein (14.3%), which is similar to the result of previous study [ 6 ]. However, presentation with locally advanced disease could be seen in a subset of the current patients.…”

“…The majority of patients reported in the previous studies [ 6 , 16 , 25 , 29 ] were metastasis-free, with only a few patients [ 7 , 15 , 29 ] presenting with pulmonary metastases, bone metastases and lymph node metastases, which indicates that MTSCC is an indolent renal cancer with a low mortality rate. In the present case series, none of the seven patients with MTSCC had metastases.…”

“…According to the WHO [ 1 ], MTSCC accounts for less than 1% of all RCC. However, the exact incidence rate of MTSCC has rarely been described in previous reports, which was only explicitly presented in Xu et al as approximately 0.52% of all RCC (22/4197) [ 6 ]. In the present study, a total of 7 cases of MTSCC accounted for 0.24% (7/2938) of all diagnosed primary RCC cases at our institution.…”

“…In a single-centre study, the majority of tumours were well-demarcated, homogenously hypoechoic and heterogeneous, while hyperechoic tumours were found in a few cases. Moreover, CDFI showed peripheral blood flow signals and no apparent blood flow into the tumours [ 6 ]. Different from previous reports, except for 3 cases, the majority of the tumours in the present study had well-defined margins and heterogeneous echo.…”

“…The exact postoperative recurrence rate of MTSCC remains unclear. Based on a literature review, most cases had no recurrence after surgery [ 6 – 8 , 20 ], only a few cases mentioned postoperative recurrence [ 30 – 33 ], and some cases were not available, died of MTSCC or other diseases during the follow-up [ 6 , 7 , 9 , 29 ]. Therefore, the surgical recurrence rate cannot be accurately predicted due to the lack of accurate data in previous reports.…”