Juxtadrenal schwannoma: verification of the diagnosis by immunohistochemical and ultrastructural studies.

Solitary schwannomas arising in the juxtadrenal region are exceedingly rare. A middle-aged woman with a confusing clinical course was found to have a solid periadrenal mass, which was surgically excised. The gross and light microscopic appearance of the tumor was suggestive but not diagnostic of this entity. However, electron microscopic evaluation of the neoplasm revealed prominent basal lamina and interdigitating cellular processes characteristic of a schwannoma. The diagnosis of schwannoma was further supported by the demonstration of S-100 protein, type IV (basement membrane) collagen, and laminin immunoreactivity by immunohistochemical techniques. The use of these special studies to arrive at the diagnosis in this case and in the larger context in the diagnosis of rare adrenal and periadrenal tumors of uncertain origin is fully discussed.