Mucin-poor mucinous tubular and spindle cell kidney cancer and clear cell renal cell carcinoma: a rare clinical case

Mucinous tubular and spindle cell carcinoma of the kidney is a rare low-grade malignant tumour and accounts for less than 1% of all renal neoplasms. The classic morphological structure of the tumor is represented by three elements: spindle cells, ducts and myxoid or mucinous stroma. This tumor is indolent with a low risk of metastasis and a favorable outcome. However, cases with relapses, metastases to regional lymph nodes, and distant metastases, which were mainly characterised by high nuclear atypia, sarcomatoid transformation and other atypical morphological features are described in the literature. Several cases of mucin-poor and mucin-free mucinous tubular and spindle cell renal cell carcinoma have also been presented, making it difficult to differentiate from other renal cell carcinomas. There are reports of cases of mucin poor mucinous tubular and spindle cell carcinoma, which were accompanied by relapses and metastases. Thus, although the tumour is indolent, careful follow-up is necessary even after radical excision. In this article, we report a rare clinical case of combination of mucin-poor mucinous tubular and spindle cell carcinoma and clear cell renal cell carcinoma of the kidney in a 50-year-old man. The results of clinical and instrumental studies, as well as the morphological features of both tumors are presented. Due to the atypical morphological structure of mucinous tubular and spindle cell carcinoma, the final diagnosis was possible using an immunohistochemical method, which demonstrated the immunohistochemical profile characteristic of this tumour