A Rare Etiology of Chronic Flank Pain: Endothelial Adrenal Cyst in a Young Female

Endothelial adrenal cysts are exceptionally rare and are often identified only when imaging is performed for other reasons. Here, we present the case of a 26-year-old woman who experienced chronic right-sided flank pain. Imaging revealed a large cyst in the right adrenal gland. Although the imaging features implied a non-aggressive lesion, a definitive diagnosis was established through histopathology. Microscopic examination revealed a unilocular cyst lined by bland endothelial cells, and cluster of differentiation 31 immunostaining confirmed its endothelial origin. This case report emphasizes the diagnostic utility of histopathological examination in evaluating adrenal cysts.