Histopathological examination of adrenal adenoma. a Macro-image of the resected adrenal adenoma. b Micro-image with low magnitude using hematoxylin-eosin staining. The adrenal adenoma composed of compact cells and clear cells. c-h Immunohistochemical staining was performed using anti-human antibodies as follows: c CYP17A1, d HSD3B type-1, e HSD3B type-2, f Dehydroepiandrosterone sulfotransferase, g CYP11B1, and h CYP11B2. The adrenal adenoma showed positive signal for cortisol producing enzymes and DHEA-sulfotransferase, which might be responsible for the high-normal serum level of DHEA-sulfate. CYP11B2 was absent in the adrenal tumors, but was positive in the extra-tumor area as aldosterone-producing cell cluster (arrows). Scale bars represent (a) 10 mm, (b) 300 μm, (c)-(e) 6 mm, (f) 7 mm, and (g) 6 mm. CYP, cytochrome P450; HSD, hydroxysteroid dehydrogenase; CYP, cytochrome P450; HSD3B, 3β-hydroxy-Δ5-steroid dehydrogenase.