[Extracranial cephalic schwannomas. Apropos of 13 cases]. / Les schwannomes exocraniens de l'extrémité céphalique. A propos de 13 observations.

ABSTRACT

The authors report a series of 13 extracranial cephalic schwannomas, treated between 1981 and 1998. Schwannomas are rare and benign tumors derived from Schwann cells. Cephalic sites represent 2.5% of all schwannomas. Their diagnosis is often delayed, because symptoms mainly consist of compression disorders. There is a female predominance. The age distribution is homogeneous. There are no risk factors. There is no predominant side. The orbit and jugular foramen are the most frequent sites. The trigeminal nerve is usually involved. CT scan and magnetic resonance imaging (MRI) specify the topography and characteristics of the tumor and can contribute to the diagnosis. Macroscopically, schwannoma is a well-demarcated, ovoid or spherical, brownish tumor, off-centered from the nerve. It is composed of soft, easily fragmented tissue. The diagnosis is often obvious on microscopic examination and rarely requires immunohistochemical confirmation. The only treatment is surgical. It consists enucleation after opening the epineurium, using on operating microscope, without disruption of the nerve. Total excision ensures recovery. The authors have observed only one recurrence (first patient operated without microscope). Compression disorders regress completely. Nerve injuries have a variable prognosis. Malignant transformation is exceptional. Type II neurofibromatosis must be excluded in young patients.