Metastases in the Orbit.

METASTATIC orbital tumours are relatively rare. This may be, as Giri (1939) has suggested, because of the difficulty encountered by blood-borne emboli in entering the right-angle bend from the internal carotid artery to the ophthalmic artery. The registry of Ophthalmic Pathology of the Armed Forces Institute of America included about 4,000 melanomata in 1958, but there were only 133 metastatic carcinomata involving the eyeball or its adnexa, and only fourteen of these occurred in the orbit. Of these fourteen cases, five were secondary to carcinoma of the breast and five to bronchogenic carcinoma, and five were of unknown aetiology. Some 3 per cent. of orbital expansive swellings are metastatic in origin. In the male the usual site for the primary tumour is the lung, in the female it is the breast, and in children the commonest orbital metastasis is from a sympathicoblastoma of the suprarenal medulla or the retroperitoneal ganglia. Among other sites which have been reported as giving rise to metastases in the orbit are the uterus, stomach, liver, kidney (hypernephroma), thyroid, prostate, and pancreas (Spaeth, 1961). With orbital metastasis from carcinoma of the breast, the diagnosis of the primary tumour precedes the onset of ocular symptoms by an average of 3 to 5 years and it is exceptional for the ocular condition to arise before the primary has been discovered. Frequently, the site of involvement is in one of the orbital muscles and diplopia has long been recognized as an early symptom (Horner, 1864; Elschnig, 1898). DukeElder (1952) pointed out that diplopia with unilateral proptosis in the adult should arouse suspicion of a metastatic deposit. Bilateral metastatic involvement of the orbit has been noted by Magnus (1929) and Kreibig (1931).