A case of giant fronto-ethmoidal osteoma (45 × 42 mm) with intracranial and orbital extension: a case report

Abstract

Background

Osteomas are the most common benign tumors of the sinonasal region. Often asymptomatic, they are frequently discovered incidentally during imaging studies conducted for unrelated conditions. Osteomas typically range in size from 2 to 30 mm; those larger than 30 mm or weighing more than 110 g are classified as “big” or “giant” osteomas. Giant osteomas of the paranasal sinuses are extremely rare and can extend into the intraorbital or cerebral space, leading to significant complications. When osteomas become symptomatic, the standard treatment is surgical intervention to alleviate associated issues and prevent further progression.

Case presentation

This report discusses a case of a giant fronto-ethmoidal osteoma (45 × 42 mm) with intracranial and orbital extension, focusing on the clinical presentation, diagnostic process, and surgical management. We present the case of a 30-year-old Black female patient from Addis Ababa, Ethiopia, with a fronto-ethmoidal osteoma causing compression of the ocular globe and the left frontal lobe. Given the intracranial extension, a combined surgical team consisting of an ENT surgeon and a neurosurgeon was assembled to address the case. The surgery was performed via an external and lateral rhinotomy with a Lynch extension approach, aiming for complete resection of the osteoma originating from the frontal sinus and extending into the orbit and intracranial space.

Conclusion

Giant sinonasal osteomas are rare tumors. The primary goal of treatment is to completely remove the tumor using a combined endoscopic and external approach. Postoperative morbidity varies depending on the surgical technique used, and there is a risk of recurrence if the tumor is not entirely excised.

Background

Osteomas are the most common tumors of the paranasal sinuses, with an incidence rate of 0.014 to 0.43% [1,2,3]. These benign tumors, primarily composed of connective tissue, frequently occur in the craniofacial skeleton, especially within the nasal and paranasal sinuses. Osteomas predominantly affect the frontal sinus (75%), followed by the ethmoid sinus (20%) and the maxillary sinus (5%) [4, 5].

These tumors grow slowly and can be associated with sinus mucoceles or chronic rhinosinusitis owing to inadequate drainage of the frontal sinus. The initial symptoms, typically resulting from sinus drainage obstruction, include pain and tenderness in the craniofacial region. Significant tumor growth can lead to ocular complications, such as diplopia, proptosis, limited eye movement, and intracranial issues, such as meningitis or cerebral abscesses. The presence of symptoms is a strong indication for surgical intervention.

Diagnosis of sinonasal osteomas involves a thorough case history, clinical examination, nasal endoscopy, and computed tomography. Osteomas are more common in males, with a male-to-female ratio of approximately 2 to 3:1, and have a higher prevalence in individuals over 40 years of age; racial prevalence is not well-documented. They can also occur in the pediatric population [6].

Clinical presentation varies depending on the size and location of the tumor. For frontal sinus osteomas, symptoms may include facial pressure, headaches unresponsive to typical treatments, mucopurulent discharge, and even facial or frontal asymmetry, as well as exophthalmos, diplopia, and eyelid swelling. In some cases, patients may also experience behavioral changes or signs of intracranial hypertension [7,8,9].

While osteomas typically range in size from 2 to 30 mm, those with a diameter greater than 30 mm or weighing more than 110 g are classified as “big” or “giant” osteomas. Giant osteomas of the paranasal sinuses are rare but can easily extend into the intraorbital or cerebral spaces, leading to significant complications [10].

Case presentation

We report the case of a 30-year-old Black female patient from Addis Ababa, Ethiopia, who first presented on 20 May 2023, complaining of swelling in the left superior inner angle of the orbit, which had slowly grown over a period of four years. She did not report any additional symptoms, particularly no compressive signs, such as headaches or diplopia.

Clinical examination revealed a hard mass in the right superior inner corner of the orbit, which appeared to be osseous, along with slight proptosis of the left eye. Examination of the nasal cavities showed a submucosally covered hard mass located above the inferior turbinates, involving the left lateral nasal wall.

The patient had no significant past medical history, cutaneous pigmentary lesions, or family history of polyposis or colorectal cancer, and reported no dental issues, soft tissue swelling, or gastrointestinal problems. Both fundoscopic and slit lamp examinations were normal in both eyes.

A computed tomography (CT) scan indicated a left fronto-ethmoidal osteoma that was protruding into the orbit and intracranially, measuring 45 × 42 mm (Figs. 1, 2, 3).

Fig. 1

Left fronto-ethmoidal osteoma, protruding into the orbit and intracranial, axial view

Fig. 2

Left fronto-ethmoidal osteoma, protruding into the orbit and intracranial, coronal view

Fig. 3

Giant frontal osteoma compressing the left frontal lobe, sagittal view

Histological analysis revealed a well-circumscribed mass composed of dense, mature, predominantly lamellar bone, with interosseous spaces containing fibrous and fibrovascular tissue (Fig. 4).

Fig. 4

A well-circumscribed mass composed of dense and mature, predominantly lamellar bone

Given these findings, a multidisciplinary surgical approach involving both ENT and neurosurgery was implemented. The first phase of the surgery was performed by the neurosurgery team, involving a bicoronal incision, craniotomy, and removal of the tumor from the left frontal sinus. The mucocele was evacuated, exposing a rough osseous tumoral mass attached to the posterior table of the frontal bone. Drilling was initiated from the posterior to the anterior wall of the frontal sinus to separate the nasal-ethmoidal-orbital fragment from the intracranial portion, continuing toward the frontal sinus recess. The frontal recess was ultimately obliterated with bone fragments, and cranialization of the frontal sinus was achieved using a pedicled pericranial graft.

The second phase of surgery was conducted by the ENT team, which performed a lateral rhinotomy with a Lynch extension incision. The periosteum was elevated to access the mass attached to the lateral nasal wall and anterior ethmoid, which was then removed by drilling it into smaller pieces (Fig. 5).

Fig. 5

After performing a Lynch incision, the ethmoidal osteoma was drilled to create a cavity, allowing the tumor to be broken down into smaller fragments

At her one-month postoperative follow-up, the patient showed some improvement in proptosis and reported no nasal congestion, orbital swelling, or visual issues, although she experienced mild frontal headaches. By the 3 and 6-month and 1-year follow-ups, her proptosis had improved further, and she had no complaints or signs of recurrence.

Discussion

Tumors larger than 30 mm are classified as giant osteomas. Their growth is slow, typically ranging from 0.44 to 6 mm per year, allowing patients to remain asymptomatic for extended periods [7]. The etiology of these tumors remains uncertain, with various theories suggesting traumatic, infectious, or embryologic origins [8].

Computed tomography (CT) is the gold standard for diagnosis. For small, asymptomatic tumors, a conservative approach is preferred, involving periodic imaging follow-ups rather than immediate surgery. Osteomas are rare, slow-growing, benign bone tumors and are the most common benign tumors of the paranasal sinuses [4, 5].

Orbital involvement is uncommon and usually occurs owing to extension from the frontal sinus or ethmoidal cells, potentially leading to ocular symptoms [10]. Rabii reported a right giant fronto-ethmoidal osteoma measuring 45 × 35 mm that protruded into the orbit. In contrast, our case describes a left giant fronto-ethmoidal osteoma measuring 45 × 42 mm, with both intracranial and orbital extension [2].

Differential diagnosis primarily includes other bone tumors, such as ossifying fibroma, osteoblastoma, fibrous dysplasia, osteosarcoma, and orbital metastasis [11]. It is noteworthy that osteomas are often discovered incidentally in about 3% of CT scans [12,13,14]. For small, asymptomatic osteomas, a conservative management strategy is typically employed, involving regular check-ups and CT scans to monitor growth and potential extension.

Osteomas can also occur in Gardner’s syndrome, an autosomal dominant disorder characterized by intestinal polyposis, cutaneous tumors, and osteomas [9]. Alexander evaluated three patients with maxillary or ethmoid osteomas and chronic sinusitis, one of whom showed signs of Gardner’s syndrome, including gastrointestinal symptoms and a positive family history of polyposis. In contrast, our patient exhibited no gastrointestinal symptoms or family history of polyposis [15].

Vishwakarma’s case report on a giant osteoma of the frontal and ethmoidal sinuses employed both open and endoscopic approaches, similar to the methodology used in our case, to achieve complete excision of the osteoma. This combination of techniques effectively ensures thorough removal while minimizing complications [16].

Conclusion

Although osteomas are the most common tumors of the paranasal sinuses and are often asymptomatic, they can present with a range of symptoms, and orbital and intracranial extensions are rare. Giant sinonasal osteomas (greater than 30 mm) are uncommon tumors. The goal of treatment is to completely remove the tumor using a combined endoscopic and external approach. Postoperative morbidity can vary depending on the type of surgery performed, and there is a risk of recurrence if the tumor is not entirely excised. Follow-up care is essential, occurring at 1 month, 3 months, 6 months, and then annually.