Mucinous tubular and spindle cell carcinoma of the kidney: Five case reports and review of the literature

Early recurrence and extensive retroperitoneal metastasis after surgery for high‑grade mucinous tubular and spindle cell carcinoma: A case report and literature review

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare subtype of renal cancer. The present report details the treatment experience of a case of MTSCC, where the patient underwent a right-side laparoscopic nephrectomy in October 2020 at Zhuji People's Hospital (Zhuji, China). A total of 3 months post-operation, multiple metastases were discovered in the right renal area and retroperitoneum, with rapid disease progression observed in the subsequent 2 months. Treatment with tislelizumab combined with pazopanib was ineffective, and the patient subsequently died. Although MTSCC is generally considered a low-grade 'indolent' tumor, with most patients achieving long-term survival post-surgery, a minority of cases, especially those of a higher grade, may experience postoperative recurrence and metastasis. Due to the rarity of metastatic MTSCC, most studies are based on small sample sizes or case reports, and there is a lack of standardized systemic treatment and follow-up strategies for metastatic MTSCC. The present paper summarizes and analyzes the clinical features, treatment methods and prognosis of metastatic MTSCC cases reported in the literature, aiming to provide assistance for the treatment and follow-up management of metastatic MTSCC. Even in cases of distant metastasis, aggressive surgical treatment, metastasectomy combined with molecular targeted or immunotherapy, may still be recommended.

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

OBJECTIVE

To further analyse the imaging features and tumour outcomes of mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney.

MATERIALS AND METHODS

The current study retrospectively reviewed the clinical information of seven patients diagnosed with MTSCC at our institution from January 2011 to March 2023.

RESULTS

The median age at diagnosis was 52 years (range, 32-66 years) and the majority of patients were female (71.4%). On conventional abdominal ultrasound, the majority of the tumours (5/7) were heterogeneous hypoechoic or slightly hypoechoic. Colour Doppler flow imaging showed blood flow within the tumour in 2 cases and peripheral blood flow signal in 1 case. On non-enhanced CT, all tumours had a spherical or ovoid shape, with an expansile growth mode, and had clear or unclear boundaries with the surrounding renal parenchyma. The tumours were either partially exophytic (n = 4) or parenchymal (n = 3), while no cases of completely exophytic tumour was observed (n = 0). On contrast-enhanced CT, the majority of tumours (5/7) showed a heterogenous pattern of enhancement and the mean tumour diameter was 6.7 ± 4.4 cm (range, 2.1-16.8 cm). All patients underwent partial or radical nephrectomy for pT1a (42.9%), pT1b (28.5%), pT2 (14.3%) or pT3b (14.3%) stage. Among these, 1 patient (14.3%) had a level I tumour thrombus at diagnosis and died of disease 24.5 months later. The remaining patients had no recurrence or metastasis.

CONCLUSION

MTSCC is not universally indolent, which tends to occur in female patients of a broad range of ages. MTSCC is a hypovascular renal tumour, which is different from clear cell renal cell carcinoma (RCC); however, it is difficult to distinguish MTSCC from other hypovascular RCC subtypes because of the overlap of their imaging characteristics.

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

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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 ADC_tumor-to-ADC_{renal 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.

CONCLUSION

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.

Mucinous tubular and spindle cell carcinoma with high-grade transformation: case report

Background

Mucinous tubular and spindle cell carcinoma (MTSCC) is a type of renal cell carcinoma (RCC) described as an entity with low-grade and low malignant potential. This report presents a high-grade transformation of MTSCC which is an uncommon finding in this subtype of RCC. Although most reported cases showed low malignant potential and good prognosis after surgical resection, a small subset of patients has been reported with aggressive phenotype and fatal outcome.

Case presentation

A case of a 23-year-old male is discussed with an incidental renal mass in the left kidney after a workup of bilateral flank pain. Morphologically, the tumor was composed of tubular structures lined by cuboidal cells mixed with spindle cells and sarcomatoid change was present in the tumor. Previously sarcomatoid change has been mostly reported along with conventional morphology in other common type of RCC with a worse prognosis.

Conclusions

The aim of this report is to draw the attention of pathologists and clinicians to the importance of high grade MTSCC owing to the unfavorable prognosis.