Background <p>The complex periadrenal anatomy complicates differentiation between adrenal tumors and masses of extradrenal origin. Given the nonspecific clinical and radiological presentations, misdiagnosis occurs frequently. We report a case where a gastric diverticula (GD) was initially misdiagnosed as a left adrenal tumor on imaging.</p> Case presentation <p>A 50-year-old male presented with epigastric pain and discomfort. Gastroscopy showed gastric retention. Non-contrast CT suggested a left adrenal tumor, while abdominal MRI indicated a left adrenal neoplasm, with possible adenoma or pheochromocytoma. Adrenal hormone levels were normal. Surgical exploration revealed a morphologically normal left adrenal gland. Further dissection identified a mass arising from the gastric posterior wall, densely adhered to the adrenal gland and masquerading as a left adrenal tumor. Macroscopic examination confirmed a hemorrhagic GD — accounting for the contrast enhancement seen on imaging and explaining the diagnostic challenge in distinguishing it from an adrenal neoplasm.</p> Conclusions <p>To our knowledge, this constitutes the first reported case of a hemorrhagic GD mimicking a left adrenal mass.</p>