Horner Syndrome Secondary to Osteochondroma of the First Rib: A Case Report

Abstract

Osteochondroma is the most common benign tumor of bone that often produces no symptoms unless the enlarged mass affects nearby structures. Rarely, Horner syndrome can be caused by an osteochondroma. A five-year-old female with a past medical history of seizure-like activity presented to the emergency department on three separate occasions within one month. She exhibited neurological deficits, including miosis and ptosis, resulting in the diagnosis of Horner syndrome. Computerized tomography (CT) demonstrated a calcified and ossified lesion arising from the right first rib and transverse process that was suspicious for an osteochondroma or chondrosarcoma with neuroblastoma lower on the differential diagnosis. Given the patient's escalating clinical symptomatology and suspicious features of the lesion, a CT guided-bone biopsy was performed. Pathology revealed an osteochondroma that was eventually resected by neurologic and orthopedic surgeries. In this case report, we review the sympathetic innervation to the head, eye, and neck, the most common etiologies of Horner syndrome, and elucidate imaging modalities useful for diagnosing osteochondroma. Horner syndrome secondary to osteochondroma of the first rib has been documented only once before.

Keywords: case report; horner syndrome; neurosurgery; osteochondroma; pediatric; radiology.

Figure 1. MRI of cervical spine (axial T2) revealing osteochondroma of the right first rib (at yellow arrowhead)

MRI - Magnetic Resonance Imaging Right paraspinal mass that appears to arise from the right first rib with continuity of the medullary cavity and bright peripheral T2 signal suggesting a cartilage cap. Findings are most consistent with osteochondroma. However, given the widening of the adjacent neural foramina and apparent extension to the neural foramina, ganglioneuroblastoma could be considered, though this would be less likely given the profuse calcification.

Figure 2. CT thorax with contrast showing osteochondroma (at yellow arrowhead) arising from the right first rib and possibly the transverse process of T1

1.8 x 1.8 x 1.6 cm calcified/ossified mass, appearing to arise from the right first rib, suggestive of osteochondroma. The almost complete calcification of this lesion makes the diagnosis of neuroblastoma less likely. CT - Computerized Tomography

Figure 3. CT-guided bone biopsy of right cervicothoracic paraspinal mass (at yellow arrowhead) that revealed osteochondroma

Patient was in a prone position for the procedure. CT - Computerized Tomography