Surgical Care
Given the benign nature of neurilemmomas, therapy is conservative and directed toward sparing the parent nerve when one is identified. The treatment of choice is gross total resection of the tumor. Care should be taken during the surgery, as 75% of patients in a case series were found to have nerve fascicular involvement. [28, 35] In one study, 75% of patients experienced some immediate neurological deficit after excision, due to transection of fascicles that ran through the tumor. [36] An algorithm has been recommended, with nerve grafting as an option for excision of mixed-nerve schwannomas in young patients. [28] See the figure below.
Although neurilemmomas are benign, incomplete excision may result in slow local recurrence. Patients with asymptomatic neurilemmomas occurring in association with NF2 frequently present with more severe neurologic deficits. These patients have a high rate of recurrence and less postoperative improvement. Malignant transformation of neurilemmomas is exceedingly rare.
Prevention
Complete removal of the tumors with maximum preservation of parent nerves can prevent local recurrence.
Long-Term Monitoring
Higher recurrence rates are noted with the intraspinal, sacral, intracranial, and plexiform variants of neurilemmoma.
Periodic follow-up care following complete removal, with maximum preservation of the parent nerves in these variants, is recommended.
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A schematic illustration of the essential microscopic features of a neurilemoma (schwannoma). A solid lesion arises within a nerve composed of a single fascicle (top). The tumor is composed of Schwann cell proliferation within the epineurium and peripherally displaced nerve fibers, resulting in nodular eccentric growth (middle). No capsule is formed in the early growth phase. The larger tumor (bottom) slightly increases the size of the parent nerve and eventually becomes separated from surrounding fascicles by a capsule formed from the perineurium and epineurium. Occasional axons are present.
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A small, clinically freely movable neurilemoma found in the subcutaneous tissue. Note the pale-yellow, somewhat-translucent cut surface. The tumor also exhibits a slight nodular growth pattern on the cut surface. Courtesy of the Atlas of Tumor Pathology Armed Forces Institute of Pathology Fascicles, Tumors of the Peripheral Nervous System. Used with permission.
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A larger neurilemoma (5 cm in diameter) arising from a peripheral nerve showing irregularly lobulated and secondary degenerative changes, ie, partly cystic with calcification (the so-called ancient change). Hemorrhage and opaque creamy-yellow areas of tumor are also seen on this cut surface.
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Cut surface of an intradermal plexiform (nodular) variety of neurilemoma. The plexiform variants of neurilemoma are rare. The area of nodularity is clearly discernible. Courtesy of the Atlas of Tumor Pathology Armed Forces Institute of Pathology Fascicles, Tumors of the Peripheral Nervous System. Used with permission
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A low-power photomicrograph of a dermal plexiform neurilemoma showing nodular aggregates of tumor cells and surrounding loose, myxomatous fibrous stroma. Hematoxylin and eosin stain at 50X magnification.
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Photomicrograph of a neurilemoma from an area with a typical Antoni type A pattern. The palisaded benign Schwann cells show nuclear crowding, with cell processes radiating toward the centers of aggregated tumor cells. Inconspicuous loose fibrous stroma is present at the periphery. Hematoxylin and eosin stain at 150X magnification.
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A photomicrograph showing a characteristic Verocay body of a neurilemoma, consisting of tight, discrete aggregates of spindle-shaped, palisaded nuclei with a central fibrillary area, representing collections of cytoplasmic processes of tumorous Schwann cells. Courtesy of the Atlas of Tumor Pathology Armed Forces Institute of Pathology Fascicles, Tumors of the Peripheral Nervous System. Used with permission.
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Transmission electron micrograph of Antoni type A tumor tissue consisting of prominent arrays of Schwann cell processes with basement membrane substance coated on their surfaces. Note the centrally located nucleus with vesicular nuclear chromatin. Uranium acetate and lead citrate stain at 15,000X magnification.
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A transmission electron micrograph of a Luse body, ie, typical collagen fibrils and adjacent basement substance. Note the long-spaced, 130-nm periodicity. Uranium acetate and lead citrate stain at 52,500X magnification. Courtesy of the Atlas of Tumor Pathology Armed Forces Institute of Pathology Fascicles, Tumors of the Peripheral Nervous System. Used with permission.
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A photomicrograph of a dermal neurilemoma with anti–S-100 protein immunostaining. The tumorous Schwann cells exhibit uniformly positive staining. Immunoperoxidase stain at 150X magnification.
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Solitary cutaneous plexiform neurilemoma shown on photomicrograph.
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Management algorithm for schwannoma nerve graft.
