Well-Defined Orbital Masses

The most common benign orbital tumor of adults is the cavernous hemangioma (in contrast to the capillary hemangioma for children). Patients have slowly progressive painless proptosis with a mass indenting the globe, showing striae in the retina and a flattened globe on imaging studies. Treatment is surgical, and complete removal is possible. Other well-circumscribed lesions include neurofibromas, schwannomas, hemangiopericytomas, meningioma, and gliomas.

A mucocele or mucopyocele is a cystic, encapsulated mass originating in a paranasal sinus (usually the frontal sinus) that follows repeated bouts of sinusitis often leading to recurrent orbital cellulitis. It is the most common cause of proptosis in children. The bony wall is not intact on imaging studies. Treatment involves antibiotics. Surgical drainage is necessary if antibiotics fail to achieve resolution of the pyomucocele, or if optic nerve compression is present.

Diffuse Orbital Mass

Diffuse orbital masses usually require a biopsy and include lymphoma, benign reactive lymphoid hyperplasia, orbital cellulitis, fibrous histiocytoma (benign and malignant), neurofibromas, and sarcomas. Figure 85-8 presents their management.

Thyroid Ophthalmopathy

Proptosis is a presenting sign of many orbital tumors. Thyroid-related immune orbitopathy represents the most common cause of both bilateral and of unilateral proptosis, however. The eye findings may be associated with clinical or laboratory evidence of hyperthyroidism, hypothyroidism, or euthyroidism. The disease is four to five times more common in women, usually those in middle age. Cigarette smoking is associated with a more fulminant course. There is considerable ignorance regarding the pathogenesis of this autoimmune entity. As a consequence, there is controversy as to guidelines for appropriate treatment, especially regarding the utility of external beam radiation therapy.⁹⁷

Lacrimal Gland Tumors

Lacrimal gland tumors can be easily found with ophthalmic B-scan at ultrasonography. The complete extent, especially bony involvement, is best demonstrated with CT scans. Contour analysis of the soft-tissue mass combined with clinical histories can help one make a presumptive diagnosis from which a treatment plan can be developed. Treatment types include steroids, biopsy, or excisional surgery.⁹⁸ When lacrimal gland tumors are bilateral, patients have either inflammatory lesions such as sarcoid, orbital inflammatory syndrome (pseudotumor), or lymphomas. Inflammatory lesions tend to be somewhat tender and represent the overwhelming majority of such lesions.

Unilateral lacrimal gland masses almost always require biopsy, although their clinical presentations may be distinct. Benign mixed tumors are painless, slowly enlarging masses of the gland in patients 30 to 40 years old causing infra-displacement of the globe. They present a rounded or globular soft tissue mass in the lacrimal gland that may even have expanded the fossa within the orbit (Figure 85-9). Treatment is surgical excision of the mass within its pseudocapsule. If possible, one should not biopsy a presumed benign mixed tumor as seeding of the orbit can occur and malignant transformation has been documented.

Figure 85-9

Adenoid cystic carcinoma of the lacrimal gland in a patient who underwent two biopsies of the mass, both of which were equivocal. The patient developed metastases to the parotid gland and later died. (Four-color version of figure on CD-ROM)

Adenoid cystic carcinoma, the most common malignant epithelial tumor of the lacrimal gland, may also present at age 30 to 40 years with infra-displacement of the globe. Frequently there is pain, numbness, diplopia, and visual disturbance. Symptoms last less than 1 year in duration, and CT scan shows a circumscribed lacrimal gland mass, frequently with blurred margins infiltrating into bone. Treatment is surgical. Recurrences may take many years to appear, but mortality approaches 90%.

Pleomorphic adenocarcinomas (malignant mixed tumors) occur in older patients, age 50 to 60 years, and are the second most common malignant tumor of the lacrimal gland. Patients may present with a painless mass de novo or they may have a history of years of a painless lacrimal gland mass with new increase in size. Finally, these patients may have a history of a prior biopsy of a benign mixed tumor that was incompletely excised many years before and now has undergone malignant transformation. Treatment is surgical. More than 75% of the patients die of metastases within 5 years.

Benign mixed tumors and carcinomas represent only 25% of lacrimal gland tumors. Nonepithelial lesions account for 75% of lacrimal gland tumors. Of these, 80% are inflammatory; previously called orbital pseudotumor, they are now part of the spectrum of orbital inflammatory syndrome. These lesions can be slow growing or sudden, painful, or painless, and may be associated with any of the earlier mentioned signs and symptoms. Their cause is immune deregulation with a mixed cellular infiltrate on histopathology composed of eosinophils and lymphocytes. Many clinicians treat painful bilateral lacrimal gland tumors without biopsy with high-dose aspirin, nonsteroidal antiinflammatory agents, systemic prednisone, and, in rare cases, low-dose irradiation.

The remainder of the lacrimal gland tumors are lymphoid in nature. In cases of lymphomas, careful pathologic analysis, aided by fresh tissue with appropriate marker studies and systemic staging, helps to define the disease and guide treatment with chemotherapy alone, local radiation alone, or a combination of both. There is much controversy about the clinical course and prognosis of periocular lymphoid lesions, but it appears that histology, stage at diagnosis, and anatomic site of involvement are predictive.⁹⁶ One- to two-thirds of patients will develop systemic disease (if not already present at the time of orbital biopsy), and almost all of these do so within 2.5 years of orbital biopsy. The higher the grade lymphoma, the greater is the chance of widespread disease (which is the opposite of nodal disease). Of patients with localized, extranodal disease, 86% were disease-free a median of 51 months after radiation treatment; 32% of patients who had disseminated disease had died.⁹⁹ If the patient is free of systemic involvement, external beam radiation to the orbit is the treatment of choice, with 2,000 to 3,000 cGy as the total dose in definitive lymphoma, and 1,000 to 2,000 cGy in atypical cases. If there is systemic involvement, then chemotherapy is added.¹⁰⁰

Some studies suggest that patients with bilateral orbital involvement have a poorer prognosis. Conjunctival lesions have the lowest likelihood (20%) of developing systemic disease. Eyelid lymphomas have the highest likelihood (67%), with orbital lesions in between (35%).⁹⁹

Bone Lesions

CT scanning best delineates bony lesions causing proptosis. Primary bony lesions include osteomas, osteogenic sarcomas, and fibrous dysplasia. Secondary lesions of bone include metastases, especially from prostate, thyroid, lung, breast, kidney, and the nonmetastatic eosinophilic granuloma (histiocytosis X spectrum).