Endoscopic Management in Fibrous Dysplasia of Ethmoid Sinus: One Case Report and Literatures Review

Discussion

Fibrous dysplasia is classified into three types: monostotic FD, polyostotic FD, and McCune-Albright syndrome. The monostotic is the most common form of FD, accounting for about 70%-80% of the FD cases^[2]. It involves 1 or 2 contiguous bones and happens in the ribs, proximal femur, tibia, and so on as we can find in the literatures^[3-5]. The polyostotic which involves multiple bones, account for 20%-30% of the FD patients, and 50%-100% of these patients involve in craniofacial bones^[6]. Moreover, the polyostotic FD is mainly distributed in the unilateral side, although the disease happened in the bilateral sides has been described in this case report^[7]. McCune-Albright syndrome is a rare congenital disorder, which is caused by sporadic gene mutations. It possesses three characteristics that is the polyostotic FD, cutaneous hyperpigmentation, and precocious puberty. Although craniofacial bone is the common site of the fibrous dysplasia involvement, it is rarely found in the paranasal sinus. The patients with monostotic FD is often asymptomatic and discovered incidentally on the radiological imaging for other reasons^[8].

The main clinical symptoms are caused by the expanding mass, which may result in bony deformity, and nasal or sinus obstruction. The obstruction caused by the FD in the normal drainage pathway of the frontal and sphenoid sinuses may cause chronic sinusitis and mucocele formation^[7,9,10]. The patient in this case report had only had anosmia before he was diagnosed as FD and the reason of leading him to the hospital was the accident injury.

When the disease processes become complicated induced by the increased orbital and intracranial pressure, patients may present with visual disturbance and proptosis, even neurological symptoms, including headache, facial pain, cranial nerve palsy, convulsion, seizure, and meningitis^[11-14].

High-resolution CT is the proper choice of the radiological examination for the diagnosis of the paranasal sinuses. CT scan can reveal the precise degree of the ossification and the radiolucent lesions in detail. The CT scan can clearly show the sclerotic, cystic, and pagetoid changes.

The FD displays nonspecific changes on the MRI which shows low signal intensity on Tl-weighted images and low to high signal intensity on T2-weighted imaging. It is difficult to differentiate FD from soft tissue sarcoma or carcinoma on the basic signalintensity^[15]. Thus, histopathologic diagnosis is necessary to differentiate FD from malignant tumors. The CT scan on the paranasal sinuses of the patient in this case report showed the irregular ground-glass –like, high-density images in the left-sided ethmoid sinus, while the MRI showed that the lesion had low T1-weighted and low T2-weighted signal intensity.

The surgical resection is the first choice to treat the FD. Although the case of total resection of the craniofacial bones involved by the FD has been reported^[16], the necessity for the surgery and the extent of the surgical resection must be based on the location of the disease, the severity of symptoms, and biological property of the lesion. However, the complete excision may result in deformity and loss of function of the surgically involved part and consequently lower the patients’quality of life caused by the significant complications of the surgery, such as serious infection, leakage of cerebrospinal fluid, orbital damage, and intracranial injury^[2,17]. Therefore, we used endoscopic sinus surgery (ESS) to resect most of the diseased bone. The ESS techniques are safe. And we believe that the endonasal endoscopic approach can remove the FD without craniofacial resection, thus avoiding serious complications caused by the radical surgery.