# Metastatic melanoma to the orbit masquerading as idiopathic orbital inflammation: a case report

## TL;DR

A rare case of metastatic melanoma in the eye was misdiagnosed as an inflammatory condition before correct diagnosis and treatment.

## Contribution

This case report adds to the limited literature on secondary orbital melanoma and its clinical presentation.

## Key findings

- A 39-year-old man presented with orbital mass symptoms initially misdiagnosed as idiopathic inflammation.
- Biopsy confirmed metastatic melanoma with likely lung spread and a history of an untreated skin lesion.
- Treatment with nivolumab and ipilimumab was initiated following diagnosis.

## Abstract

This case highlights an exceedingly rare presentation of secondary orbital melanoma and reviews the current literature on orbital melanoma.

Case presentation: A 39-year-old man was referred to our clinic after acute-onset decreased vision and left upper eyelid ptosis. Outside-hospital magnetic resonance imaging (MRI) showed an enhancing left superior orbital apex mass. The patient was initially treated for presumed idiopathic orbital inflammation without improvement. An orbital biopsy was performed, and the pathology showed secondary malignant melanoma. A computed tomography (CT) chest scan showed likely pulmonary metastases. Upon further questioning, the patient reported a history of an incompletely excised pigmented forearm lesion. The patient was treated systemically with nivolumab and ipilimumab.

Conclusions and importance: Despite its rarity, orbital melanoma should be considered in the differential diagnosis of patients with an orbital apex mass that does not respond to treatment for idiopathic orbital inflammation.