Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases.

OBJECTIVE

The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series.

METHODS

We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated.

RESULTS

Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed.

CONCLUSION

By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.