Schwannoma of the Adrenal Gland

Abstract

Primary schwannomas of the adrenal gland are extremely uncommon. We report the clinical and pathologic features of two cases, occurring in a 73-year-old man and a 26-year-old woman, both of whom presented with abdominal pain and an adrenal mass on imaging studies. Both tumors were characterized by a proliferation of cytologically bland spindle cells. One case exhibited alternating compact Antoni A areas and less cellular Antoni B areas consistent with conventional schwannoma, whereas the other case was hypercellular and composed predominantly of Antoni A areas consistent with cellular schwannoma. Reactive inflammatory cells and lymphoid aggregates were present throughout both tumors. The diagnosis of schwannoma was supported by positive immunoreactivity for S-100 protein and collagen IV and absence of reactivity for keratin, muscle related antigens, and CD34 in both cases. Electron microscopy was also performed in the case of cellular schwannoma, which showed ultrastructural features confirming the diagnosis. Both cases had a favorable outcome without evidence of recurrence or metastasis. Because of its rarity, schwannoma occurring at this particular site can pose problems in diagnosis and should be distinguished from other spindle cell lesions of the adrenal gland.

Adrenal Schwannoma: A Rare Type of Adrenal Incidentaloma

“…1,3,13 Verocay bodies, nuclear-free zones in between regions of nuclear palisading, can be seen, as well as thick-walled, hyalinized blood vessels. 3,4,6,13 Reactive inflammatory cells and lymphoid aggregates can also be seen. The inflammatory infiltrate is typically seen at the periphery of the tumor.…”

“…6 Adrenal schwannomas are thought to arise from Schwann cells associated with these nerves. 2,4 The cases reviewed in the literature demonstrate a broad age range, from 14 to 89 years, with a median age of 49 (Table 1). There is a slight female predominance, with a female to male ratio of 1.2:1.…”

“…They are also characterized by an absence of Verocay bodies and may have increased mitotic activity. 4,13 The distinction between cellular and conventional schwannomas is an important one, as we shall see in our discussion on the differential diagnosis of adrenal schwannomas.…”

“…1,4,13 Necrosis and mitotic figures are usually absent. 1,4 Cellular schwannomas consist entirely of Antoni A areas with intersecting fascicles of spindle cells and are devoid of hypocellular, Antoni B areas. They are also characterized by an absence of Verocay bodies and may have increased mitotic activity.…”

Juxta-adrenal malignant schwannoma with lymph node metastases

“…Visceral schwannomas are rare and only a few cases of adrenal schwannomas have been reported. [1][2][3] More particularly, juxta-adrenal malignant schwannoma are extremely rare and lymph node metastasis is uncommon. 4 We report the first case of juxta-adrenal malignant schwannoma with lymph node metastases.…”