Ptosis secondary to orbital metastasis undetected by magnetic resonance imaging: A case report.

We report a patient with isolated ptosis secondary to orbital metastasis but no evidence of a neoplastic process on magnetic resonance imaging (MRI). A 69-year-old male was referred to our hospital with ptosis of the right upper eyelid and secondary frontalis muscle overaction on the left side for six months. The palpebral fissure was 3mm on the right and 16mm on the left, and levator function was 6mm and 19mm respectively. Three years previously, he had undergone surgical resection of the left lower lobe of the lung due to a T1 N0 M0 adenocarcinoma, and no recurrence had since been observed. An MRI was performed to rule out ptosis secondary to metastasis. Thyroid dysfunction and myasthenia were also ruled out. The ptosis was attributed to an isolated microvascular third nerve palsy. A standard external levator advancement was performed. Six months after the surgery, the patient presented with intense pain, minimal ptosis, edema and diplopia. A new MRI revealed an orbital metastasis measuring 2.4×1.0×1.6cm in the superior orbit, exerting mass effect on the superior rectus and the levator palpebrae superioris muscle. A positron emission tomography scan revealed a recurrence of the lung cancer with multiple bony metastases. The patient underwent chemotherapy consisting of the taxol-carboplatin protocol. Our report highlights the importance of a high index of suspicion of a neoplastic etiology in patients with mild symptoms and a history of cancer even if imaging does not initially reveal a mass or infiltration.