Orbital Cavity Tumors

Tumors

1. Orbital Tumors

All orbital tumors displace the globe and cause exophthalmos that is frequently associated with limited ocular motility. Some tumors also cause specific additional symptoms and findings. These are discussed separately for each of the tumors presented in the following section.

Hemangioma

Hemangiomas are the most common benign orbital tumors in both children and adults. They usually occur in a nasal superior location. Capillary heman-giomas are more common in children (they swell when the child screams), and cavernous hemangiomas are more common in adults. Treatment is only indicated where the tumor threatens to occlude the visual axis with resulting amblyopia or where there is a risk of compressive optic neuropathy. Capillary hemangiomas in children may be treated with cortisone or low-dose radia-tion therapy.

Dermoid and Epidermoid Cyst

These lesions are the most common orbital tumors in children. Etiologically, they are choristomas, i.e., dermal or epidermal structures that have been dis-placed into deeper layers. However, they usually are located anterior to theorbital septum (and therefore are not in the actual orbit itself). Lesions locatedposterior to the orbital septum usually become clinically significant only in adults. Treatment consists of complete removal.

Neurinoma and Neurofibroma

These tumors are often associated with Recklinghausen’s disease (neurofibro-matosis). If they occur in the optic canal, they must be removed before theycause compressive optic neuropathy.

Meningioma

A meningioma can proceed from the optic nerve (meningioma of the opticnerve sheath) or from within the cranium (sphenoid meningioma). Symp-toms vary depending on the location of the tumor. Exophthalmos, limited motility, and compressive optic neuropathy can result. Hyperostoses are frequent findings in radiographic studies. Treatment consists of neurosurgi-cal removal of the tumor. Like neurinomas, 16% of all meningiomas are

associated with neurofibromatosis (Recklinghausen’s disease). Meningiomasof the optic nerve sheath are usually histologically benign but can recur if notcompletely removed. Interestingly, the average age of patients is 32; 20% are younger than 20.

Histiocytosis X

This is a generic term for the proliferation of Langerhans’ cells of undeter-mined etiology; all three of the following types can cause exophthalmos where there is orbital involvement:

❖ Letterer-Siwe disease (malignant).

❖ Hand-Schüller-Christian disease (benign).❖ Eosinophilic granuloma (rare and benign).

Leukemic Infiltrations

Leukemic infiltrations occur especially in acute lymphoblastic leukemia and in a special form of myeloid leukemia (granulocytic sarcoma or chloroma). Inflammation is present in addition to exophthalmos.

Lymphoma

Lymphomas can occur in isolation or in systemic disease. Cooperation with an oncologist is required. The disorder may be treated by radiation therapy or chemotherapy. Usually these tumors are only slightly malignant. The highlymalignant Burkitt’s lymphoma, which has a high affinity for the orbital cav-ity, is a notable exception.

Rhabdomyosarcoma

This is the commonest primary malignant tumor in children. The tumor often grows very rapidly. Because of the accompanying inflammation, a differential diagnosis should exclude orbital cellulitis. Other indicated diagnostic studies include a CT scan and possibly a biopsy. With modern therapeutic regimes such as chemotherapy and radiation therapy, curative treatment is possible in many cases.

2. Metastases

In children, the incidence of metastasis is higher in the orbital cavity than in the choroid. In adults, it is exactly the opposite. The most common orbital metastases in children originate from neuroblastomas. Malignant tumors from adjacent tissue can also invade the orbital cavity.

3. Optic Nerve Glioma

In children, this is the second most common potentially malignant orbitaltumor. In 25% of all patients, the optic nerve glioma is associated with neuro-fibromatosis (Recklinghausen’s disease). Fifteen percent of all patients withneurofibromatosis develop optic nerve gliomas. The prognosis is good only where the tumor is completely resected.