ORBITAL TUMORS AND PSEUDOTUMORS

SUMMARY Twenty-four orbital tumors and 4 pseudotumors diagnosed in biopsy material among 596 ophthalmic tumors examined during the 1998-2003 period are presented according to patient age and sex, tumor histology and immunohistochemistry. The most common orbital tumors were lipomas, meningiomas and lymphomas, with a peak incidence in the seventh decade of life. Most orbital tumors of childhood are distinguished from those occurring in adults. Most pediatric orbital tumors are benign (developmental cysts, capillary hemangioma, hamartoma), with a peak incidence in the first decade of life. Orbital tumors show a bimodal age distribution. Benign orbital tumors are more common than the malignant ones. Rhab-domyosarcoma (embryonal type) is the most common orbital malignancy in childhood, and lymphoma in adults. Orbital pseudotumors is a term that has been widely accepted to describe inflammatory lesions of the orbital tissue with a mixed inflammatory infiltrate with a varying grade of fibrosis. Histologic classifica-tion of orbital pseudotumors is presented. Orbital pseudotumors occur predominantly in older individuals and are infrequent in children and young individuals. These imply a nonspecific inflammatory process of unknown etiology, and have been included as part of the differential diagnosis of orbital tumors