Metastasis of solid tumors in extraocular muscles

Three autopsy cases with discrete metastatic involvement of one or several extraocular orbital muscles by disseminated amelanotic melanoma (one case) and lobular mammary adenocarcinoma (two cases) associated with extensive meningeal involvement are reported. Clinical ocular symptoms including pain, exophthalamus, and diplopia occurred 6 months to almost 5 years after resection of the primary tumor; in two cases CT scan showed spindle-like enlargement of orbital muscles. Pathologic examination disclosed solid localized metastatic deposits in several extraocular muscles of one (breast carcinomas) or both orbits (melanoma), with diffuse invasion of striated muscle, but without necrosis, inflammation, or involvement of other orbital adnexa, eye ball, optic nerves, or orbital bone. Since no continuous invasion of orbital or intraocular structures by diffuse meningeal blastomatosis was histologically observed, rare metastatic involvement of extraocular muscles via hematogenic route is suggested.