Unilateral proptosis as the initial manifestation of malignancy

Proptosis, a common sign with a broad differential diagnosis, is defined as anterior displacement and protrusion of one or both orbital globes. Patients can present with varying degrees of chronicity, visual loss and associated symptoms. The etiology of acquired unilateral proptosis is diverse, ranging from benign to life-threatening. The causes of unilateral proptosis include traumatic, vascular, endocrine, inflammatory, infective and malignant. Breast carcinoma is the most common metastatic cause of proptosis; however, proptosis has never been reported as the initial manifestation of breast carcinoma. Our patient presented with unilateral proptosis secondary to an intraorbital lesion and histopathology of orbital lesion was suggestive of metastatic breast adenocarcinoma. She was later diagnosed to have primary breast carcinoma. We present this unusual case of a 56-year-old woman who presented with proptosis as the initial manifestation of a metastatic breast malignancy.