Unusual Cause of Horner Syndrome 13 Years After In Situ Ductal Carcinoma.

Horner syndrome can be caused by a wide range of pathologies along the sympathetic nerve chain, from the hypothalamus to the orbit. Imaging workup of Horner syndrome is necessary given the potential for deadly lesions, especially in a patient with a previous cancer history. The authors report a case of a woman who presented with a preganglionic Horner syndrome secondary to vertebral metastasis from previously diagnosed breast cancer that involved the neural foramina at T1 and T2.