Schwannoma of the adrenal gland: report of two cases.

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.