Adrenal schwannoma: A case report of an unusual incidentaloma

Abstract

Introduction and importance: Adrenal schwannomas are extremely rare tumors often misdiagnosed. The patients are usually asymptomatic while some present with non-specific abdominal pain. Only a few cases are reported to date.

Case presentation: We here present a case of a 55-year-old Nepalese man presented with nonspecific abdominal pain at our Outpatient Department (OPD) found to have mass on ultrasonography of abdomen. On further investigation with Contrast Enhanced Computerized Tomography (CECT) of the abdomen and pelvis, a well-defined heterogeneous adrenal mass of size (7.8 ∗ 8.3 ∗ 6) cm with foci of calcification was seen in the left retroperitoneum. The intraoperative finding of adrenal mass and histopathology of resected mass was suggestive of schwannoma arising from the adrenal gland which was further confirmed by immunohistochemistry.

Clinical discussion: Adrenal schwannoma can mimic tumors like pheochromocytoma, adrenal adenoma, cortical carcinoma, neuroblastoma, and other masses. Only 1-3% of schwannomas are retroperitoneal. Radiological findings of this tumor are non-suggestive. The histological section shows spindle cells with Antoni A and Antoni B regions while positive staining of S-100 protein in Immunohistochemistry.

Conclusion: The diagnosis of adrenal schwannoma in the retroperitoneum is often challenging. The treatment of choice is surgical resection with a good prognosis.

Keywords: Incidentaloma; Retroperitoneal tumor; Schwannoma.

Fig. 1

CECT of abdomen & pelvis showing a heterogeneous adrenal mass of size (7.8 ∗ 8.3 ∗ 6) cm with foci of calcification in the left retroperitoneum (yellow arrow).

Fig. 2

(a, b): Gross appearance of the resected adrenal gland shows well-encapsulated mass which on the cut section shows heterogeneous gelatinous to solid grey white areas.

Fig. 3

(a): Adrenal schwannoma (H&E, ×40 magnification) showing a well-encapsulated tumor with spindle-shaped neoplasm in the adrenal gland. (b): Verocay bodies with palisading nuclei seen in hypercellular Antoni A areas.

Fig. 4

(a): Immunohistochemistry of tumor cells showing strong nuclear and cytoplasmic immunoreactivity for S-100 protein. (b): Immunohistochemistry of tumor cells showing focal weak cytoplasmic desmin immunoreactivity. (c): Immunohistochemistry of tumor cells showing negative immunoreactivity for SMA. (Positive internal control of smooth muscles in the vessel wall). (d): Immunohistochemistry of tumor cells showing focal weak membranous immunoreactivity for CD117.