Sarcomatoid change associated with epithelial-mesenchymal transition in mucinous tubular and spindle cell carcinoma of the kidney: a case report.

We report an unusual case of mucinous tubular and spindle cell carcinoma (MTSCC) with sarcomatoid change in an 80-year-old Japanese male. In a resected specimen, a grayish-white tumor was found in the left kidney, and several metastases were observed in the right cervical bone and liver. Histologically, most of the main tumor examined showed MTSCC with sarcomatoid change. The transitions between the MTSCC and sarcomatoid components suggested that sarcomatoid transformation had occurred in the MTSCC. Immunohistochemically, the epithelial-mesenchymal transition (EMT)-associated marker ZEB1 was expressed in the sarcomatoid and transitional components. In contrast, ZEB1 expression was negative in the MTSCC component. The present findings support the view that MTSCC with sarcomatoid change represents MTSCC that develops a sarcomatoid component via EMT of the MTSCC component. EMT plays an important role in sarcomatoid change; thus, we conclude that MTSCC with sarcomatoid change is an 'EMT associated tumor'. IJCEP