The orbit in a broad sense describes the cavity containing structures necessary for the ocular operation and the bony architecture surrounding them.
Since the orbit is a relatively small anatomical area with minimum redundant space, any lesions occupying the area, that increase the orbital volume may result in proptosis of the globe (Exophthalmos) and may adversely affect the visual function and operation of the extraocular muscles.

Orbital tumors in children
Capillary hemangiomas are the most common orbital tumors observed in children. Other benign lesions of the orbit include dermoid cysts, lymphangiomas and histiocytic tumors.
Rhabdomyosarcoma is the most common primary malignant orbital ailment in children. These destructive lesions usually occur in children younger than 2 years or older than 6 years.
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.

Orbital tumors in adults
In adults, cavernous hemangiomas are the most common de novo orbital tumefactions. These lesions are usually well tolerated by the patient and handled by conservative therapy unless a loss of visual acuity or visual field is observed.

The decision for a surgical intervention is taken when there is a need for a confirmatory biopsy or when the lesion is directly or indirectly adversely affecting the globe or the vision. For example, in a patient with a salmon-patch colored lesion on the conjuctiva, biopsies are required to confirm and assist in the diagnosis and the subtyping of the presumed lymphomatous lesion. Other damages exert their destructive effects through their bulk, and diminishing these damages is essential in restoring orbital integrity. In other occasions, compression of the optic nerve requires decompression of the orbital contents.