Dermatologic Manifestations of Neurilemmoma (Schwannoma) Clinical Presentation

Updated: Dec 15, 2017
  • Author: Kara Melissa T Torres, MD, DPDS; Chief Editor: Dirk M Elston, MD  more...
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Presentation

History

While neurilemmomas almost always occur as solitary lesions with no associated genetic syndrome, in some instances they are multiple or occur in association with neurofibromatosis, particularly neurofibromatosis (NF) type 2. Rare examples are associated with NF1 (ie, von Recklinghausen disease).

Patients generally report an asymptomatic slow-growing tumor that has been present for several years. Pain, tenderness, and paresthesia may be expected if the tumor is large or, by virtue of a deep-seated location, is impinging on neighboring structures. Symptoms have been reported in up to one third of patients. [23] Waxing and waning of the tumor size may be noted and is attributed to fluctuations in the amount of cystic change within the neoplasm.

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Physical Examination

Neurilemmomas have a predilection for the head, neck, and flexor surfaces of the upper and lower extremities. Case reports describe solitary schwannomas in a subungual (under the nailbed) location, [24] on the foot, [25] the base of the tongue, [26] and on the lip. [27] The spinal roots and the cervical, sympathetic, vagus, peroneal, and ulnar nerves are affected most commonly. In a case series from 2013, [28] 50% of patients had involvement of mixed sensory and motor nerves. Superficial neurilemmomas in the skin may display a prominent plexiform (nodular) growth pattern. [29]

A Tinel-like sign was described in 81% of 234 cases of benign solitary schwannomas. [30]

Neurilemmomatosis or schwannomatosis, a variant of NF2, is an autosomal dominant disorder with full penetrance. Although very few familial cases of neurilemmomatosis have been reported, most (90%) neurilemmomas in this setting have been multiple, encapsulated, and located in the subcutaneous tissue, [31] while 10% have been plexiform, involving the neck, trunk, and extremities.

When the tumor involves small nerves (see the image below), it is freely movable. When the tumor involves large nerves (see the image below), it is movable but moves along the long axis of the nerve where the attachment restricts mobility.

A small, clinically freely movable neurilemoma fou 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.
A larger neurilemoma (5 cm in diameter) arising fr 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.

Most neurilemmomas are asymptomatic, nontender, and not associated with neurologic signs or symptoms.

A special form of inherited neurilemmoma (ie, psammomatous melanotic variant) occurs in the setting of Carney complex, which is an autosomal dominant disorder characterized by the combination of spotty pigmentation (ie, lentigines), cardiac myxomas, and endocrine overactivity. More than 50% of patients with a psammomatous melanotic neurilemmoma (ie, schwannoma) have Carney complex. In contrast to the conventional neurilemmoma, the melanotic variant is not associated with NF2; thus, conventional neurilemmomas are not observed in association with Carney complex. Another difference between the two variants is that approximately 10% of melanotic tumors are malignant, whereas conventional neurilemmomas almost never undergo malignant change.

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