Introduction

Epibulbar osseous choristomas are rare congenital collection of mature compact bone most often located in the superotemporally. The embryogenesis of these lesions seem to correlate with the scleral ossicles seen in avian anatomy and may represent abnormal activation of embryonic pleuripotential.

To the best of our knowledge only 52 cases have been reported worldwide till 2006. We report our case of purely temporal epibulbar osteoma located near lateral canthus making it more unique.

Case Report

A seven years old male presented history of swelling in the right eye present since birth. It was temporal in location and was gradually increasing in size. There was no history of trauma and there was no history of any systemic disease.

On examination, a pea size nodule was seen 8 mm from limbus located near the lateral canthus which was reddish in color, firm to hard in consistency . It was freely mobile over the sclera. Apart from this nodule, eye was externally normal. Fundus showed no abnormality. Provisional diagnosis of dermoid was made and excisional biopsy was done. CT scan showed no evidence of calcification.

Surgery was uneventful. The tumor was freed from overlying conjunctiva and underlying sclera. The tumor measured 0.5 X 0.3 cm. the conjunctiva was sutured with the running 8-0 Vicryl sutures. Histopathology of the excised mass showed the tissue to be composed of mature bony trabeculae enclosing osteocytes and diagnosis of epibulbar osteoma was made (Fig 1).

Figure 1

Figure 1: Histo-pathological picture showing mature bony trabeculae

Discussion

Epibulbar Osteoma was first reported by Von Graefe¹ in 1863. Boniuk and Zimmerman² described twenty cases of this tumor till 1962.They described osseous choristomas as congenital lesions with a potential growth but sometimes may occur in association with trauma. Upper temporal is the commonest location but in our case it was purely temporal situated close to the lateral canthus. They also observed the tumor to be free from conjunctiva and sclera as was in our case too.

Sheth et al³ reported first case of epibulbar osteoma from India and they reviewed 26 cases which were reported till 1978. Gayre et al ⁴ was able to collect 51 cases till 2002 and described them as choristomatous lesion of conjunctiva containing bone and occur in association with other choristomatous lesions in 10% of the cases. It has also been found to be attached to the underlying muscle and sclera.

Devina and Rana⁵ reviewed 52 cases of osseous choristomas which were reported till 2006. To the best of our knowledge no other case has been reported since 2006. we report our 53rd case of our epibulbar osteoma.