6. Local recurrences are common. Distant metastasis is unusual.

VI. MALIGNANT SKULL BASE TUMORS

A. Olfactory Neuroblastoma

1. Uncommon neuroendocrine tumor arising from the nasal olfactory epithelium.

2. No sexual predilection, occurring in all ages.

3. Usually presents with nasal obstruction and epistaxis.

4. At time of diagnosis, an olfactory neuroblastoma usually has intracranial and dural

involvement.

5. Lymphatic metastasis occurs 10–30% of the time.

6. Treatment has involved various sequences of surgery, radiation, and chemotherapy.

7. Recurrence occurs in 30–40% of patients.

B. Chondrosarcoma

1. Seventy-five percent occur at the middle fossa skull base.

2. Affects both sexes, with peak incidence of 30–50 years of age.

3. Pain is prominent secondary to bone destruction.

4. Treatment is surgical excision.

5. Frequent local recurrence with rare systemic metastasis.

6. Five-year survival is 50%.

C. Nasopharyngeal Carcinoma

1. Squamous cell carcinoma of the nasopharynx.

2. Strong association with Epstein-Barr virus.

3. Especially common in China and Southeast Asia.

4. Male:female preponderance is 3:1.

5. Most common site is at the fossa of Rosen-müller—present with serous otitis media,

nasal obstruction, and/or epistaxis.

6. Most common presentation: asymptomatic cervical adenopathy.

7. Commonly involves the cavernous sinus, cranial nerves VI, IV, III, II, I (in decreasing

order).

8. Prognosis is best with undifferentiated type (60% 5-year survival) and worse with

well-differentiated squamous cell (20% 5-year survival).

9. Treatment: radiation therapy with chemotherapy.

D. Orbital Rhabdomyosarcoma

1. Most common head and neck soft tissue malignancy in children.

2. Peak incidence around age 5 with a slight male predominance.

3. Caucasian children affected 3 times as often as other races.

4. Usually presents as rapidly progressive unilateral proptosis.