Neurilemmomas are benign tumors that originate in the Schwann cells that comprise nerve sheaths. Accordingly, the neoplasms are sometimes alternatively referred to as benign schwannomas.

The cause of neurilemmoma growth is unknown, but the tumors are occasionally associated with von Recklinghausen disease. Neurilemmomas are typically encapsulated and well defined. Symptoms related to the tumors are often vague, which can greatly hinder an accurate diagnosis.

The growth of neurilemmomas is most common in adults, and the tumors can affect a wide variety of nerves. The neoplasms are most common in the head region, accounting for approximately 6 to 8 percent of all primary intracranial tumors. Of the cranial nerves, the eighth nerve is the most frequent origin of neurilemmomas. The tumors generally respond well to local resection and recurrence is rare.

Histologically, two distinct regions of a neurilemmoma are recognized. Antoni A regions are areas that contain a large number of cells, chiefly benign spindle cells organized into overlapping bundles. The cells sometimes surround eosinophilic regions known as Verocay bodies. The density of cells in Antoni B regions is much less than in Antoni A regions. Loose connective tissue that has the appearance of a myxoma (benign tumor found predominantly in the heart) serves as the background to Antoni B cells.

Neurilemmoma at 40x Magnification - A few reports of malignant change have been documented, but such neurilemmoma transformation is considered highly unusual.

Neurilemmoma at 10x Magnification - On average, it takes five years for a diagnosis of neurilemmoma to be confirmed after initial symptoms appear.