A Rare Adrenal Incidentaloma: Adrenal Schwannoma

Abstract

Adrenal schwannoma is an extremely uncommon cause of incidentaloma. It originates from neural sheath Schwann cells of the adrenal gland. We report the case of a left adrenal schwannoma incidentally discovered in a 32-year-old woman during examination of bloated feeling and stomach ache. The patient was incidentally found to have a left adrenal mass of 9 cm on abdominal ultrasonography. Computed tomography (CT) of the abdomen and [¹⁸F] fluorodeoxyglucose positron emission tomography (PET) were also performed. Metabolic evaluation was unremarkable. Due to the large size of the tumor, left adrenalectomy was performed. The postoperative course was uneventful. Histological examination established the diagnosis of schwannoma. This diagnosis was supported by immunohistochemistry of S-100 and vimentin positivity. In conclusion, adrenal schwannoma is an extremely rare entity and can grow considerably in size. The present case report emphasizes that clinicians should be aware of the possibility of retroperitoneal schwannoma. Total excision of benign schwannoma is associated with a favorable outcome. To our knowledge, there are case reports of schwannoma with CT and magnetic resonance imaging findings in the literature, although this is the first schwannoma case with PET-CT imaging.

Adrenal Schwannoma: A Rare Type of Adrenal Incidentaloma

“…3,6 It is commonly seen to arise from the peripheral nerves and cranial nerves at the head and neck region. It rarely involves the visceral organ in the case presented, where it arises from the adrenal medulla.…”

“…[1][2][3] Other areas where they can be found include retroperitoneum and juxta-adrenal area. 1,3 Adrenal schwannoma is thought to arise from Schwann cells from the phrenic nerve, the vagus nerve, or sympathetic trunk that innervate the adrenal medulla. 6 The explanation for this is related to the embryological development of the adrenal medulla where it is formed by cell migration from the neural crest.…”

“…There is no gender dominance and can occur at any age group. 3,5,7 Majority of adrenal schwannoma is solitary and benign. Malignant transformation may be found in association with von Recklinghausen disease or neurofibromatosis.…”

“…The disease commonly 1 Medical Officer, 2 Professor, [3][4][5] Surgeon, 6 Consultant and Senior Lecturer arises either from the adrenal medulla or from the cortex but may arise from any tissue of the adrenal gland. The common benign causes are adrenal hyperplasia and pheochromocytoma.…”

“…Tumor arising from the nerve sheath of the adrenal gland or adrenal schwannoma is extremely rare. [1][2][3] Out of 381,200 autopsy specimen of adrenal incidentalomas examined, only one adrenal schwannoma was detected. 4 In another study, out of 1,111 cases of adrenal incidentalomas examined, only two cases (0.18%) of adrenal schwannoma were detected.…”