腎門部異位腎上腺皮質：罕見病例報告

沈毓明、陳俊吉

彰化基督教醫院泌尿外科

Ectopic adrenal cortex at the renal hilum: A Rare Case Report

Yu-Ming Shen, Chun-Chi Chen

Division of Urology, Department of Surgery, Changhua Christian Hospital

Introduction

Ectopic adrenal tissue represents misplaced cortical cells from embryologic development and is occasionally found along the urogenital tract. Most cases are detected in neonates and regress with age, making adult presentation exceedingly rare. While typically asymptomatic and discovered incidentally, its imaging appearance may mimic lymphadenopathy or other retroperitoneal tumors, often prompting surgical intervention for definitive diagnosis. Hilar localization is particularly uncommon. We report a rare case of ectopic adrenal cortex at the left renal hilum, incidentally discovered during health screening, successfully excised through a robotic-assisted retroperitoneal approach.

Case presentation

A 58-year-old man underwent abdominal CT during a health examination, revealing a 2.2 cm solid lesion at the left renal hilum, suspect enlarged lymph node or tumoral lesion. The patient was asymptomatic and had normal adrenal hormone levels. Robotic-assisted retroperitoneal tumor excision was performed on July 19, 2023. Intraoperatively, a golden, friable, and highly vascular mass was found near the left renal vein and completely excised with minimal blood loss (150 mL). Grossly, the specimen measured 3.0 × 2.5 × 1.7 cm. Microscopically, polygonal adrenocortical cells with clear to eosinophilic cytoplasm were arranged in nests and surrounded by a preserved reticulin framework. Immunohistochemistry for SF-1, α-inhibin, and Melan-A confirmed ectopic adrenal cortex. The postoperative course was uneventful, and the drain was removed on postoperative day 3.

Discussion

Ectopic adrenal cortex represents misplaced cortical tissue resulting from embryologic migration errors. During early fetal development, adrenocortical primordia derived from the coelomic mesothelium may fragment or deviate from their normal position, forming small cortical rests along the urogenital ridge. These remnants usually regress but occasionally persist into adulthood, most often near the gonads or kidney. Hilar involvement is extremely rare, with only sporadic cases reported.

On imaging, ectopic adrenal cortex can appear as a small, well-defined soft-tissue mass mimicking lymphadenopathy, lipoma, or metastatic lesions, particularly near major renal vessels. Because imaging findings are nonspecific, histologic confirmation is essential. The lesion is composed exclusively of cortical cells without medullary elements and shows positivity for SF-1, α-inhibin, and Melan-A, which are reliable markers of adrenocortical origin. Although usually nonfunctional, ectopic adrenal tissue may undergo hyperplasia or neoplastic transformation, especially after adrenalectomy.

Surgical excision provides both diagnostic confirmation and symptom prevention. The robotic-assisted retroperitoneal approach offers excellent visualization and precise dissection within the confined hilar space, minimizing blood loss and postoperative morbidity. This case highlights the importance of including ectopic adrenal cortex in the differential diagnosis of indeterminate hilar lesions to avoid unnecessary radical surgery.

Conclusion