案例報告: 罕見的腎上腺腫瘤- 腎上腺神經鞘瘤

葉星佐、陳彥達

高雄長庚紀念醫院泌尿科

Case Report: A Rare Adrenal Tumor- Adrenal Schwannoma

Hsing-Tsuo Yeh, Yen-Ta Chen

Kaohsiung Chang Gung Memorial Hospital, Department of Urology

Introduction: Schwannoma is a rare and benign neoplasm arising from neural crest cells, mostly occur at skin and subcutaneous tissue of the head and neck. Retroperitoneal schwannomas account for 1–3% of all schwannomas. In particular, adrenal schwannoma is even more rare, and is difficult to distinguish it from other adrenal diseases based on image. In this report, we introduce the case of a left adrenal schwannoma.

Case Report:  This 56-year-old male has underlying disease of hypertension and ICH post craniotomy and external ventricular drain in 2020/07 with focal seizure attack. He was informed of elevated liver enzymes during health examination, and went to local clinic for abdominal echo, which revealed a 6 cm mass at left supra-renal region. Thus, he came to our hospital for further help, where abdominal CT found a 7.3 x 6.1 x 7.1 cm left retroperitoneal well-defined mass with focal enhancement.  Physical exams were unremarkable. Urine analysis showed clean urine, and cytology showed negative for malignancy. Blood tests, including all functional adrenal exams were all within normal range. After discussing with patient, we arranged laparotomy for left retroperitoneal tumor on 2023/10/12.

Gross section from pathology revealed a well-circumscribed and encapsulated tumor with solid and soft texture, mottled tan-yellow color, with obvious degenerative changes characterized by areas of hemorrhage and cyst formation. The adrenal gland is identified in the attached adipose tissue. Micro sections showed ancient Schwannoma of retroperitoneum characterized by the pattern of alternating antoni A (hypercellular) and antoni B (hypocellular) areas, the mitotic figure is not found. Clinical course was uneventful, and he was soon discharged on 5th post-operative day. He received regular outpatient department follow up, and latest renal echo showed no evidence of recurrent tumor.

Discussion: Schwannoma is a neurogenic tumor, generally occuring between the third and the sixth decades of life. About 1% of all retroperitoneal tumors are Schwannomas and only 1–3% of all Schwannomas are located in retroperitoneum. Most of these adrenal tumors is non-functioning and often appears heterogeneous on CT and MRI. For this reason, adrenal schwannoma is often misdiagnosed for the tumors of the retroperitoneum such as myelolipoma, adrenocortical carcinoma, pheochromocytoma, ganglioneuroma, neuroblastoma and adrenal metastatic lesion. Though Schwannoma is mostly benign and slow growing, but in advanced stages, space-occupying mass signs manifest with lumbar heaviness or pain, neuralgia and paresthesia in the distribution of the affected nerves, ureteral obstruction. Typical Schwannoma is a solitary mass with well-defined margins. “Ancient” Schwannoma is a variant with degenerative changes and a very good clinical outcome after complete surgical resection. In conclusion, despite adrenal schwannoma being a rare and typically benign tumor, since it cannot be distinguished from other malignant diseases on preoperative imaging, it should always be considered in any adrenal tumors.