原發性腎臟神經內分泌腫瘤–罕見個案報告

 顏維晨、曹智惟、蒙恩、高建璋

 國防醫學院三軍總醫院外科部泌尿外科

 Primary renal neuroendocrine tumor- A rare case report and literature review

Wei-Chen Yen , Chih-Wei Tsao, En Meng , Chien-Chang Kao

Division of Urology, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Neuroendocrine neoplasms (NENs) are rare, and the incidence is about 7 per 100,000 individuals, with the most common primary sites being lung, gastrointestinal tract, and pancreas. And primary neuroendocrine tumors of the kidney making up less than 0.4% of all NENs. Primary renal neuroendocrine tumors can be classified as either well-differentiated neuroendocrine tumors (such as carcinoid tumors) or poorly differentiated neuroendocrine carcinomas (such as small cell carcinomas). Well-differentiated NETs are generally, indolent, slow-growing and have a better prognosis than poorly differentiated NECs, which tend to be more aggressive.

We present a case of 30-year-old female without systemic nor family history. An incidentally discovered renal tumor noted via abdominal sonography during a physical checkup. CT scan was arranged for further evaluation and showed a 4.6 cm parapelvic renal tumor with mild contrast uptake but without early enhancement and early washout characteristics typically present on renal cell carcinoma.  There was only minimal hydronephrosis noted. No hematuria complained. Cystoscopy and ureteroscopy were also checked and showed no intraluminal lesion. Hand-assisted laparoscopic radical nephrectomy, right was performed for the patient. The surgical pathology showed renal neuroendocrine tumor, grade 1, pT3aN0M0, stage III. The tumor located at hilar region, abutting renal parenchyma and

renal pelvis with proliferative index <2% and no increased mitotic figures (< 2 mitoses per 2mm²), invading pelvicalyceal system and renal sinus fat with vascular invasion. The patient discharged six days after operation under stable condition. Regular OPD follow up had been arranged.

Renal neuroendocrine tumors (NETs) encompass a rare group of neoplasms that include carcinoid tumors and small cell carcinomas. Although both tumor types show reactivity with neuroendocrine markers, they are histologically distinct. Small cell carcinomas are poorly differentiated, high-grade tumors, having a relative short overall survival whereas renal carcinoid tumors are more well-differentiated, tending to have prolonged survival even with metastases.

Although considered to be low- grade NETs, renal carcinoid tumor can pose an aggressive clinical course. Patients with primary renal carcinoid tumors frequently present with metastatic disease (45.6% of reported cases) which can be explained by the fact that development in retroperitoneum, a potentially expandable space. Tumors smaller than 4 cm or confined to the renal parenchyma are associated with a better prognosis due to less metastasis event. Purely solid tumors and those with a higher mitotic rate have also been reported to be associated with a worse prognosis. Patients above 40 years-old is associated with a more rapid progression and a more severe initial presentation.

Nephrectomy and regional lymph node dissection has been proven to be curative for renal carcinoid tumors and low-stage renal NETs of other histology. Surgical excision should be viewed as primary treatment for these patients but may require additional therapy. In a reviewed literature, 47% of patients who underwent nephrectomy for renal carcinoids were disease-free after a mean 43-month follow-up. About small cell carcinomas, unfortunately, often present with extrarenal invasion and may not be able to complete resection. Due to the rarity of these tumors, no standard treatment has been approved for locally advanced or metastatic disease.