罕見腎臟腫瘤: MiT 家族易位性腎細胞癌

謝育哲、劉建良、黃冠華

奇美醫學中心 外科部 泌尿科

Rare renal tumor: MiT family translocation renal cell carcinoma

Yu-Che Hsieh, Chien-Liang Liu, Steven K. Huang

Department of Surgery, Division of Urology, Chi Mei Medical Center, Tainan, Taiwan

Case report:

A 30 years old male patient denied any systemic disease or family history. This time, he suffered from incidental finding left renal tumor by health exam. Initially, he visited the Nephrology OPD, abdomen computed tomography(CT) revealed that an exophytic nodule in middle pole of left kidney with hypervascular enhancement and hypodensity on delay phase, about 2.0cm, suspicious of renal cell carcinoma. Thus, he was referred to our GU OPD. He denied fever/chills, upper respiratory tract infection, abdomen pain, nor dysuria. The RENAL score of the tumor was 7p. Robot assisted retroperitoneal laparoscopic partial nephrectomy was done smoothly. The whole operative time was about one hour. Pathology showed left kidney MiT family translocation associated renal cell carcinoma (pT1a), with surgical margin free. No post- operative complication was noted. During follow-up after six months at our OPD, CT showed no CT evidence of recurrence.

Discussion:

Renal cell carcinomas (RCCs) are a heterogeneous group of cancers. The major histological subtype of RCCs is the clear cell carcinoma, followed by papillary and chromophobe. MiT family translocation RCCs are among these rare cancer subtypes, comprising 1–4% of adult renal cell carcinomas, and were first included as a separate classification of neoplasia by the WHO in 2004, regarded as “Xp11.2 translocation carcinomas”. These cancers are originated from the translocation of the genes of the transcription factors TFE3 and TFEB, both members of MiT family.

On imaging, Xp11.2 translocation RCCs figure as heterogeneous formations arising from the renal medulla often confined to the kidney, despite few descriptions of exophytic growth and involvement of the renal sinus. Its presence of nodal spreading is around 47% of the patients by the time of the diagnosis.

Macroscopically, renal tumors related to Xp11.2 alterations are similar to other RCCs: solid yellow-tan masses, frequently containing necrosis and hemorrhage.

For localized tumors smaller than 7 cm, partial nephrectomy, either by open surgery or by laparoscopy, is a nephron-sparing option when the contralateral kidney is healthy. Similarly to what is observed in other RCCs, radiotherapy and chemotherapy are not effective for treatment of MiT family translocation tumors.