Teaching Neuro Images: Osteochondroma arising from the clavicle causing ipsilateral Horner syndrome

Abstract

A 17-year-old female smoker noticed right eyelid droop for 6 months, with a constant right-sided pressure-like headache with photophobia, phonophobia, and nausea, right-sided lacrimation, and right-sided rhinorrhea. Examination revealed right Horner syndrome. A mass was palpable on the anterior aspect of her neck. Ultrasound of the neck, MRI head, and CT thorax showed a bony mass arising from the right medial clavicular head (figure 1). Histopathology from the excision confirmed an osteochondroma (figure 2). This was removed surgically with partial resolution of symptoms. This case demonstrates a rare cause of Horner syndrome 1,2 and the importance of thorough imaging of the sympathetic chain.