Ethmoido-orbital osteoma

Abstract

Introduction: Primary orbital bone tumors of the orbit are a heterogeneous group of conditions constituting 0.6-2.0% of all orbital tumors1. Osteomas are benign, slow growing bone tumors that can occur in any bone, usually in the appendicular skeleton. They are most common tumor of the paranasal sinuses, originating in decreasing frequency from the frontal, ethmoid, maxillary and sphenoid sinuses.2 Osteomas are most commonly small and asymptomatic, being noted incidentally on up to 3% of head CT scans obtained for other indications.3 Secondary orbital extension from the paranasal sinuses has historically been considered uncommon, with an incidence ranging from 0.9% to 5.1%.4 Primary orbital bone osteomas are very rare.5-9 Orbital involvement is usually a result of invasion from adjacent sinuses and occurs most frequently in the ethmoidal, frontoethmoidal, and frontal regions.10,11 Although unusual, orbital involvement can cause eye pain, diplopia, metamorphopsia, globe displacement, epiphora, dacryocystitis, orbital cellulitis, and vision loss.4 In our case, we reported 19 years woman with a primary orbital osteoma and successfully removed by surgical excision. A case report: Chief complaint: A 19 years old Nepalese young woman presented with double vision and gradually bulging her right eye. She did not complain any tenderness and pain in affected side. These symptoms started 3 years ago. Systemic and family histories were unremarkable. On examination: The best corrected visual acuity was 20/20 in her both eyes with no afferent pupillary defect. Extraocular motility was normal. She had 4 mm proptosis in the right eye and globe out displacement was noticed. Head CT: Coronal and axial CT scan shows round shaped, homogeneous well demarcated mass attached to right ethmoid sinus. The mass was bigger than eyeball and globe out displacement was noted. Management: Firstly, we planned as nasal endoscopic surgery to remove the lesion but couldn’t be taken out due to its size and characteristics.The patient underwentplanned total resection through a modified Lynch incision a whitish round mass with smooth surface, and measuring 3.5x3x2.5 mm mass (Fig. 3B) was found attached to the ethmoid bone which was completely excised from the bone by blunt dissection under general anesthesia.Histopathology report showed that specimen consists of discrete bony mass measuring 3.5x3x2.5 cm. Sections from mass show lamellar bony tissue and atypia is not seen. Histopathological diagnosis was consistent with an osteoma. For complete resection of osteomas, greater surgical exposure is necessary than for resection of similarly sized soft-tissue tumors. In our case, 7 days after surgery, the patient’s eye was in normal position, motility was intact. andcomplete wound healing with minimal scar formation was detected. 6 months follow up no recurrence occurred. Discussion: Georgalaset al.13 proposed treatment when the following criteria aremet: 1) Osteomas associated with symptoms after all otherexplanations for the symptoms have been excluded, 2) Large (extending to >50% of the frontal sinus) or growing osteomasas seen on serial CTs, and 3) Osteomas associated withcurrent complications (mucocele, orbital symptoms, neurologicsymptoms, external deformity) or imminent (completeobstruction of the frontal recess or intraorbital/intracranialextension) complications. The surgery should be aimed to total removal of the tumor without any damage to the adjacent organs. Conclusion: Osteomas are the most common tumor of the paranasal sinuses (noted in up to 3% of coronal CT images), but secondary extension in or primary involvement of the orbit is rare. In our case, we successfully removed the lesion with complete surgical excision.Approximately 5% of osteomas become symptomatic or require surgery.4 Osteomas may be more common in men, with the reported male to female ratio ranging from 1:1 to 2.4:1.2 Depending on the location of osteoma, it may cause a progressive proptosis, ocular movements limitation, diplopia, facial pain or paresthesia.7,14 Histopathologically, osteomas are composed of osseous and fibrovascular tissues and according to the dominated tissue are classified to ivory (compact), trabecular (cancellous) and fibrous (spongy) types which may have osteoblastic activity as a sign of invasiveness.4,15,16,17