[Exophthalmos secondary to a lateral rectus muscle metastasis]

60-year-old male, with metastatic adenocarcinoma of the rectum-sigmoid colon, who developed exophthalmos due to a tumour in the lateral rectus muscle, compatible with a diagnosis of metastasis.

Metastasis in the extraocular muscles are very uncommon, but should form part of the differential diagnosis of any patient presenting exophthalmos, since although the majority of patients with such metastasis have a previously diagnosed malignant tumour, there are cases where they lead to the diagnosis of the primary tumour.