A 47-year-old man was diagnosed with primary aldosteronism due to two left adrenal adenomas, suggested on computed tomography (CT) to be located at the upper and lower adrenal portion. However, adosterol scintigraphy revealed negligible uptake at the upper portion of the left adrenal. Laparoscopic left adrenalectomy was performed, but macroscopic examination of the specimen revealed only one adrenal tumor. Continued surgical exploration detected another mass between the spleen and the stomach, which was demonstrated to be continuous with the stomach and was eventually diagnosed as a gastric diverticulum. Postoperatively, aldosteronism resolved and repeat CT revealed staining of the adrenal pseudotumor when oral contrast was administered. Since organs located near the adrenals can simulate adrenal tumors, caution must be exercised in interpreting suprarenal masses on CT. To our knowledge, this is the first reported case of concurrent pseudotumor and true tumor of the ipsilateral adrenal.