6.2 Tumors of Sinus and Nasopharyngeal Origin

Most tumors that secondarily involve the orbit arise from the paranasal sinuses. Such tumors are slightly more common than primary orbital tumors [14, 15]. Epithelial malignancies of the sinuses frequently spread to the orbit; Conley [16] noted that 45% of such tumors invade the orbit. Approximately 80% of sinus and nasopharyngeal tumors with orbital invasion are epithelial [17]. Batsakis [18] divided epithelial malignancies of the nasal cavity and paranasal sinuses into two groups: (1) those arising from metaplastic epithelium, including squamous cell carcinoma and transitional tumors, and (2) those arising from the mucoserous epithelium, including adenocarcinoma and salivary gland neoplasia (e.g., adenoid cystic carcinoma, mucoepidermoid carcinoma, and rare malignant salivary neoplasia). Epithelial tumors occur more frequently in men than women by a ratio of 2:1, and the incidence peaks at 40–60 years [17].

The orbit is at risk of invasion from tumors of sinus or nasopharyngeal origin because it shares three thin, bony walls with the sinuses and nasal cavity: the roof, medial wall, and floor. Tumors can extend into the orbit by bony destruction, through suture lines, or via the perforating blood vessels and nerves that run through the orbital walls. Sinus tumors typically do not show early clinical signs, usually presenting after the tumor has grown to a large size, resulting in a poor prognosis. By definition, orbital invasion of sinus tumors reflects an advanced stage of disease. In these instances, proptosis and globe displacement are common, and the lesion is typically readily visible on orbital computed tomography and magnetic resonance imaging (Fig. 6.2). In the case of suspicious orbital lesions, images should be acquired up to the base of the sinuses to permit adequate evaluation.

6.2.1 Squamous Cell Carcinoma

Squamous cell carcinoma is the most common epithelial tumor secondarily invading the orbit, accounting for 60% of such lesions [19]. Two-thirds of invading squamous cell carcinomas originate within the maxillary sinus, with the ethmoid being the second most common site of origin [17, 19]. In more than 90% of instances, squamous cell carcinomas do not declare themselves clinically until they breach the sinus of origin [17]. Once the orbit is invaded, growth of such tumors may lead to clinical signs including pain and paresthesia in the face or teeth, trismus, a full alveolus, palatal erosion, chronic sinusitis, cheek swelling causing facial asymmetry, nasal obstruction, epistaxis, nasal congestion or discharge, and distortion of the maxilla [17, 20]. Ophthalmic features denoting the maxillary sinus as the site of origin include nonaxial upward globe displacement, infraorbital pain and paresthesia, decreased vision, ophthalmoplegia, diplopia, lower lid fullness, and epiphora [17, 20]. The frequency and the severity of ocular and orbital symptoms in patients with secondary orbital epithelial malignancies attest to the relatively silent origin and late-stage presentation of these tumors. When carcinoma arising in the

Fig. 6.2 Magnetic resonance image of a left maxillary sinus tumor invading the orbit

ethmoid sinus invades the orbit, lateral and inferior globe displacement may be seen. Nasopharyngeal carcinoma may spread to the orbit through the inferior orbital fissure and have proptosis as a late finding (Fig. 6.3). In all instances of sinus carcinoma invading the orbit, inflammatory signs may be suggested by injection, chemosis, and edema; however, tenderness and significant erythema are unusual [17]. The features that help distinguish secondary epithelial malignancies from practically every other tumefaction of the orbit are chronic, progressive, and relentless facial pain and paresthesia (in 60% of patients) and nonaxial globe displacement (in 48% of patients) [17]. In contrast to secondary epithelial tumors invading the orbit from adjacent structures, metastatic orbital tumors are painful in only about 25% of cases, and proptosis is typically axial [17]. Radiologic findings consist of either focal or widespread destruction of the sinuses, with invasion of adjacent structures by a typically large solid tumor mass, often with extension to the skull base. Histopathologically, the majority of cases consist of moderately well-differentiated keratinizing squamous carcinoma [21].

Treatment of squamous cell carcinoma with orbital invasion is usually a combination of radical surgical excision and radiation therapy and often necessitates exenteration if the periorbita has been invaded [19]. Combined-modality chemotherapy and radiation therapy can also yield nice outcomes in some cases of nasopharyngeal carcinoma with orbital invasion. In addition, patients with regional nodal disease but without distant metastases are potentially curable and should be treated aggressively with neck dissection and postoperative adjuvant irradiation of the nodal

Fig. 6.3 Computed tomography image of a nasopharyngeal carcinoma invading the posterior orbit

basins [17]. In recent years, there has been a shift toward preservation of the ocular structures with reconstruction of surrounding tissues whenever possible. This is particularly true when there is evidence of only minimal orbital invasion or extraperiosteal involvement [17]. Historically, prognosis has been dismal, with a 5-year survival rate of approximately 35% [17]. Tumors arising from the posterior portion of the maxillary sinus are associated with a worse prognosis because of proximity to the orbit, cribriform plate, and pterygoid region [17]. Approximately 10–22% of squamous cell carcinomas have regional lymph node metastases on initial presentation [17]. Mortality is largely linked to the inability to eradicate local disease, with approximately 18% of patients ultimately developing distant metastases [17].

6.2.2 Other Tumors of Sinus and Nasopharyngeal Origin

Transitional carcinomas originate from the epithelium of the nasal cavity and paranasal sinuses, most commonly arising from the ethmoid sinuses or nasopharynx [17]. The majority of lesions are benign papillomas characterized by multiple and multifocal occurrence and local recurrence [17]. Though these lesions may recur, the large majority remain benign. Only 7–9% undergo malignant transformation, and most of these originate in the lateral nasal wall [17]. Treatment is radical surgery, radiation therapy, or both.