Malignant rhabdoid tumour in an adult kidney: A case report.

Malignant rhabdoid tumours (MRTs) in the kidney are rare paediatric tumours that are extremely rare in adults. We herein report the case of an adult patient with a renal MRT. A 79-year-old Japanese woman was found to have a tumour sized 63×48 mm in the left kidney, in addition to multiple metastatic bone and lymph node lesions. The needle biopsy specimen obtained from the patient's kidney revealed tumour cells with rhabdoid characteristics: The cells appeared large, round or polygonal, with eccentrically located nuclei and prominent nucleoli. Immunohistochemically, the tumour cells were positive for vimentin, epithelial membrane antigen, CAM 5.2, and p53, and negative for INI1, cytokeratin (CK)7, CK20, α-methylacyl-CoA racemase, S100, CD45, renal cell carcinoma marker, anaplastic lymphoma kinase, α-smooth muscle actin, desmin, MyoD, myogenin, human melanoma black 45 and melan A. Therefore, the tumour was diagnosed as an MRT located in the kidney. Although the patient was treated with axitinib, a tyrosine kinase inhibitor, the renal tumour and its metastatic lesions continued to progress, and the number of metastatic lesions increased. The patient succumbed to the disease 5 months after the first hospital visit. The disease progression was rapid, with a poor prognosis, consistently with previous reports that of MRTs in the adult kidney.