Discrete metastasis of solid tumors to extraocular muscles.

We report five cases of discrete solid tumor metastasis to extraocular muscles. Computed tomography confirmed that orbital involvement in all cases was confined to the extraocular muscles; there was no tumor in the bony orbit or in the adjacent paranasal sinuses or intracranial space. In two of our five cases, ophthalmic signs were the first evidence of metastatic disease; in the three other cases, there was a known history of cancer prior to orbital involvement. Pain, diplopia, and proptosis were the most common presenting manifestations. Neuroimaging demonstrated bilateral focal, nodular enlargement of multiple extraocular muscles in three cases. Diffuse enlargement of a single muscle occurred in the two other cases, inclusive of the tendinous insertion in one instance. Fine-needle aspiration biopsy provided a diagnosis of undifferentiated malignancy in all four cases in which it was performed.