[A CASE OF RAPIDLY ADVANCING RENAL MUCINOUS TUBULAR AND SPINDLE CELL CARCINOMA]

Renal mucinous tubular and spindle cell carcinoma (MTSCC) is a rare, renal epithelial neoplasm that is an established subtype in the World Health Organization 2004 classification. A 75-year-old-woman was diagnosed as having atypical mycobacterial infection and hepatitis C. Computed tomography showed a hypovascular mass 35 mm in diameter in the left kidney. The renal tumor was diagnosed as MTSCC by pathological examination of the renal biopsy specimen. The patient underwent laparoscopic left radical nephrectomy via a retroperitoneal approach. Pathological findings showed left renal carcinoma (MTSCC, pT3aN0M0), and we did not perform adjuvant therapy. The patient developed lung nodules one month after the operation that were diagnosed as lung metastasis by pathological examination of a bronchoscopic biopsy specimen. She then developed progression of lung metastasis, mediastinal lymph node metastasis and bone metastasis. We explained the necessity of therapy, but she refused therapy and died of disease progression four months after the operation. MTSCC is thought to have a relatively good prognosis, but care must be taken because, as in our case, tumor progression can occur rapidly.