Although rare there have been a few reports of rib exostosis, encroaching into the spinal canal, and leading onto neural deficit [3
]. However, to the best of our knowledge there have been no reports of the aforementioned presentation being associated with a scoliotic deformity.
Exostoses that cause neurological symptoms usually arise from vertebral pedicles or lamina [4
]. In this case however the CT scan clearly demonstrated that the exostosis arose from the rib head (). As described in other similar reports this patient underwent an excision of the lesion leading onto a resolution of the neurological deficit. Early excision is warranted to prevent further neurological compromise [1
] and to eliminate the low probability of malignant transformation [5
The presence of an associated left upper thoracic scoliotic deformity in this patient was indeed perplexing. Though tumors like osteoid osteoma and osteoblastoma have been known to cause a pain-provoked scoliosis [6
], these lesions, whether they arise for the rib or vertebra, have consistently arisen on the concave side of the curve [7
]. The exostosis in this case arose from the ribs on the convex side. Furthermore it has been suggested that after removal of these lesions the scoliosis usually resolves [7
] whereas in this case, a year after removal of the rib lesion, the deformity had infact progressed. Furthermore an osteochondroma is an unusual tumor to cause scoliosis. Infact a review of literature revealed only one report of a vertebral osteochondroma presenting as a thoracolumbar scoliosis [8
] and another as an atypical spinal curve [9
]. There have been no reported cases of a rib osteochondroma presenting as upper thoracic scoliosis. Though it has been stated that left thoracic curves are invariably associated with underlying pathology warranting 'full investigation' [10
] this patient had no underlying disease of the spinal cord like a syrinx, Arnold Chiari malformation or any osseous vertebral anomalies (). Therefore in the absence of a identifiable cause it is maybe rational to suggest that this patient had a symptomatic rib exostosis along with a coincidental idiopathic scoliosis.
In the light of the resolution of his more distressing symptoms arising from neural compromise, the patient was not overly concerned about the deformity and even though the curve angle had increased to 38° we felt that it was premature to surgically intervene. A similar reported case by Fiechtl et al. [9
] had taken up to 2 years for resolution. Also Goldberg et al. [10
] in a school screening program observed that left curve patterns were less likely to progress and less likely to require surgery. However the patient has been advised a regular follow-up.
In conclusion, the possibility of a rib exostosis may be kept in mind when patients with hereditary multiple exostosis present with neural compromise. The presence of an associated scoliosis in this case was probably coincidental.