Carcinoid tumour metastatic to the orbit with infiltration to the extraocular orbital muscle.

Ninety-three percent of symptomatic patients with small intestinal carcinoid tumours have metastases. The most common sites of metastases are lymph nodes and liver. Orbital metastases have rarely been described and the majority of them involve the choroid rather than extraocular orbital structures. We report a patient who developed proptosis, impairment of vision and reduced ocular motility on the left side, eighteen months after operation for primary intestinal carcinoid tumour with hepatic metastases. CT and MR studies revealed the tumour mass infiltrating the inferior rectus muscle. Biopsy examined by imprint and frozen section showed tumour consistent with metastatic carcinoid. The tumour was removed. HE and staining for cytokeratin, chromogranin, NSE, serotonin, somatostatin and gastrin showed that the tumour tissue corresponded to that of the primary intestinal carcinoid tumour. Intramuscular orbital metastasis from a carcinoid tumour is a rare occurrence. Diagnosis may be difficult, especially where no evidence of primary carcinoid tumour is present. Metastatic orbital carcinoid should be suspected in patients with a clinical history of carcinoid tumour and who develop ocular complaints and mass lesion in the orbit. Complete surgical removal of the tumour is important for optimal restitution of vision and eye movements.