A case report of mucinous tubular and spindle cell carcinoma of the kidney.

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare type of kidney tumor that has only recently been described, with less than eighty cases in the literature. This was only recognized as a specific entity in the World Health Organization 2004 classification of Renal Cell Carcinoma (RCC). MTSCCs are polymorphic renal neoplasms characterized by small, elongated tubules lined by cuboidal cells with cords of spindled cells separated by pale mucinous stroma. We report the case of a 57 year old lady who had an incidental finding of a mass in her right kidney. The radiological features were consistent with a RCC and following a multidisciplinary team discussion she underwent a laparoscopic radical nephrectomy. Macroscopic examination revealed a well circumscribed 6.5 × 6 × 6.5 cm right lower pole mass. Histologically it was composed of elongated tubules, small tubules and papillary structures with a necrotic centre. The cells demonstrated cuboidal and spindle cell morphology. Histological grade was Fuhrman grade 2. The majority of MTSCCs are indolent, and there are only two reports of distant metastases which responded favorably to adjuvant sunitinib. To date there is no international consensus on long term surveillance of these patients. Due of the favorable prognosis with this type of tumor, MTSCC must be differentiated from papillary renal cell carcinoma to avoid administration of excessive adjuvant treatment to patients.