Horner's syndrome as a presenting sign of metastatic testicular malignancy

Horner's syndrome, first described in 1869 by a Swiss ophthalmologist, is a characteristic triad of features that results from an interruption of the sympathetic pathway. The ophthalmic manifestations arise due to paralysis of the sympathetically innervated superior tarsal muscle (also known as Muller's muscle, which dilates the pupil) and thus the patient will have a pupillary miosis associated with a mild ptosis. The one non-ophthalmic feature of Horner's syndrome is facial anhydrosis. Horner's syndrome occurs as a result of disease affecting the ipsilateral sympathetic pathway along its course from the hypothalamus to the orbit, however it may also be congenital or iatrogenic. In this case report we aim to highlight that Horner's syndrome may be a presenting feature of metastatic testicular carcinoma, especially in young men. The use of appropriate radiological investigations can identify this potentially life-threatening malignant aetiology of Horner's syndrome.