The orbit is an anatomically complex structure containing the globe, extraocular muscles, fat, and vascular, nerve, glandular, and connective tissues.
The orbit in the broadest sense describes the cavity containing structures essential for ocular function and the bony architecture that encases them.
Since the orbit is a relatively small anatomical area with little wasted space, space-occupying lesions that increase orbital volume may result in proptosis of the globe (exophthalmos) and may adversely affect visual and extraocular muscle function.
Primary orbital tumefaction, although quite rare, encompasses a lexicon of benign and malignant neoplasia. All anatomical structures of the orbit can give rise to neoplasia. Direct extension from contiguous anatomical structures, lymphoproliferative disorders, and hematogenous metastasis results in secondary orbital invasion.
Capillary hemangiomas are the most common orbital tumors found in children. These histologic benign lesions manifest at birth or within the first 3 months of life, enlarge rapidly, and begin to commence contracting around age 1 year. Other benign orbital lesions include dermoids, lymphangiomas, and histiocytic tumors
Rhabdomyosarcoma is the most common primary malignant orbital tumefaction in children. These devastating lesions usually occur in children younger than 2 years or older than 6 years, and they have a predilection for the superior nasal orbit
Neuroblastomas, Ewing sarcoma, Wilms tumor, ,and leukemias are the more common metastatic orbital lesions afflicting children. Other malignant lesions include Burkitt lymphoma and granulocytic sarcoma.
In adults,cavernous hemangiomas are the most common de novo orbital tumefaction. CT scan reveals a round, encapsulated, well-defined orbital lesion. These lesions usually are well tolerated by the patient and managed by conservative therapy and reassurance, unless visual acuity or field loss is found
Initiation of surgical intervention occurs when confirmatory biopsy is needed or when the lesion is directly or indirectly adversely affecting the globe or the vision. In a patient with a salmon-patch colored lesion, confirmatory biopsies are needed to aid in the diagnosis and subtyping of the presumed lymphomatous lesion. Other lesions exert their destructive effects through their bulk, and diminishing these lesions is essential in restoring orbital integrity. In other situations, compression of the optic nerve requires decompression of the orbital contents