Adrenal schwannoma: A rare type of adrenal incidentaloma

Abstract

Benign tumor of the myelin sheath or schwannoma is not uncommon, especially when it involves the peripheral or cranial nerves. But adrenal schwannoma is very rare and commonly presented as an incidentaloma. Adrenal incidentaloma by itself is not uncommon as more imaging is now being performed and its incidence is estimated to be around 4 to 6%. Clinical and imaging studies are not able to differentiate adrenal schwannoma from other causes of incidentaloma, making its diagnosis difficult preoperatively. We report a 64-year-old man who underwent computed tomography (CT) abdomen as part of his health-screening program. An 80 × 70 mm right adrenal tumor was discovered from the CT with features suggestive of malignancy. He has neither apparent abdominal symptoms nor symptoms related to adrenal hypersecretion. Apart from chronic hypertension, he also suffered from morbid obesity with body mass index (BMI) of 38. There was no clinical feature to suggest Cushing disease, pheochromocytoma, or primary hyperaldosteronism. His laboratories evaluation including endocrinology studies consistent with a non-functioning adrenal mass. He underwent an uneventful standard transabdominal right adrenalectomy. Immunohistochemistry report showed the tumor has characteristic of Antoni A type and positive for S-100 immunochemistry stain. The diagnosis of adrenal schwannoma was made. This case report highlights the difficulty in the management of adrenal incidentaloma.