25 Benign Tumors of the Nasal Cavity and Paranasal Sinuses

This chapter gives a general overview of benign tumors of the sinonasal cavity. With the exception of osteomas, the neoplasms discussed here are relatively rare in occurrence when compared with inflammatory sinonasal disorders such as rhinosinusitis. Although there is quite extensive histopathologic diversity among this group of neoplasms, their presentation, work-up, and management are generally uniform. Two of the most commonly discussed benign sinonasal neoplasms, juvenile nasopharyngeal angiofibroma (JNA) and inverting Schneiderian papilloma, have been covered in Chapter 27 and will not be discussed here in detail.

Prevalence

Osteoma is the most common benign sinonasal neoplasm with an annual incidence of up to 80 per 100,000.¹ Eller and Sillers identified osteomas in up to 3% of routine head computed tomography (CT) scans.^1,2 Hemangioma represents the most common soft tissue neoplasm, and inverted papilloma, which represents up to 4% of all nasal tumors, is the most common epithelial neoplasm.³ The majority of sinonasal neoplasms, however, are rare, with most references in the literature existing as case reports or small case series.

Clinical Presentation

Presentation varies and is attributable to a combination of factors, most notably aggressiveness of the lesion and location. The most common presentation is that of unilateral nasal obstruction, reported in up to three-quarters of patients.¹ Chronic sinusitis, epistaxis, headache, or an incidental finding on examination/imaging are other common presenting complaints for these uncommon tumors. Progression and extension beyond the confines of the sinonasal cavity, typically late in the disease process, can also lead to less common presenting complaints such as external nasal mass/deformity, globe displacement, epiphora, vision loss, diplopia, oral cavity obstruction,⁴ meningitis, subarachnoid hemorrhage, or even pneumocephalus.⁵

Diagnostic Work-up

The diagnostic work-up for any nasal mass begins with a thorough history, noting length, location, severity, and change-over time of symptoms. As noted above, presenting symptoms will vary, but tend to parallel those of inflammatory sinonasal disorders, such as rhinosinusitis.

A complete head and neck examination including nasal endoscopy should be performed. When possible, a biopsy of unilateral nasal masses should be done. Vascular tumors or encephaloceles, as suggested by clinical picture or imaging, should not be biopsied. Signs indicative of advanced tumors, such as cerebrospinal fluid rhinorrhea, globe displacement, external nasal deformity, and numbness, should be identified. Furthermore, superimposed paranasal sinus infections should be identified and addressed before surgical intervention.

Imaging studies generally include CT and magnetic resonance imaging (MRI) scans. CT scans best characterize the bony anatomy and can suggest intracranial or orbital extension. However, in cases with extensive paranasal sinus opacification or with skull base erosion, MRI better distinguishes tumor from adjacent secretions or neural tissue. When indicated by the extent of the lesion, referral to ophthalmology, neurosurgery, or oral and maxillofacial surgery, or dentistry should be made.

Treatment

In general, complete excision of most benign sinonasal tumors is curative. Currently, minimally invasive, endoscopic approaches are the mainstay. However, strategically placed incisions, such as brow, eyelid, or gingivobuccal sulcus incisions, may improve access and extirpation of difficult-to-reach tumors, as discussed in Harvey et al.¹ For more advanced disease or for improved access, traditional “open” approaches may be necessary. Close postoperative surveillance is required not only to detect recurrent tumors but also to assess the physiologic function of the sinonasal cavity following treatment.

Specific Neoplasms

Table 25.1 provides a complete list of tumors, organized in the fashion of the World Health Organization guidelines.⁶ The following is a brief description of some of the more common benign tumors found in the sinonasal cavity.

Table 25.1 Benign Neoplasms of the Nose and Paranasal Sinuses

^aTumors of increased malignant potential.

Inverted papilloma is the most common of the epithelial benign tumors. Refer to Chapter 26 for further details.

Exophytic

Exophytic papilloma (EP) is the second most common Schneiderian papilloma and is located almost exclusively on the nasal septum.^6,7 Also referred to as everted or fungiform papilloma, these lesions exhibit a histologic pattern of branching exophytic proliferations with fibrovascular cores covered by epithelial hyperplasia varying from squamous to transitional to respiratory in addition to occasional mucin-filled microcysts.^6,7 EPs are more common in males by a factor of 2:1 to 10:1 and are typically diagnosed in the third to sixth decades.^6,7 There is strong evidence associating the development of EP with human papilloma virus (HPV) infection, primarily subtypes 6 and 11. In Lawson’s recent meta-analysis of HPV in all Schneiderian papillomas, the adjusted prevalence of HPV in the setting of EP ranged from 45 to 86%.⁸ Physical examination reveals small (0.1 to 1.5 cm) yellow-tan or gray verrucous exophytic lesion affixed to underlying mucosa by a narrow stalk.⁷ Unlike inverted papilloma, malignant transformation is exceedingly rare.⁷ Complete resection, including a small margin of healthy tissue at the point of attachment, is curative, but incomplete resection can lead to recurrence rates of 22 to 50%.^6,7

Oncocytic

Oncocytic Schneiderian papilloma (OSP), or cylindrical cell papilloma, is the least common Schneiderian papilloma, representing 3 to 7% of papillomas.^3,7,9 OSPs are equally distributed among males and females and are diagnosed most frequently in the sixth decade.⁶ Like inverted papilloma, OSPs are rarely identified on the septum and localize to the maxillary, ethmoid, or rarely sphenoid sinuses.³ Physical examination typically reveals a polypoid pink, gray, or tan lesion emanating from the lateral aspect of the nasal cavity.^6,9 Oncocytic papillomas are highly metabolically active and have also been identified on positron emission tomography scan in the process of metastatic evaluation, raising concern for potential metastasis.¹⁰ No association between OSP and HPV has been identified.^6,8 Histologically, OSPs demonstrate exophytic fronds in addition to endophytic areas with oncocytic change and seromucinous glands with frequent microabscesses.^6,7 Although malignant transformation to squamous cell carcinoma, mucoepidermoid carcinoma, sinonasal undifferentiated carcinoma, and small cell carcinoma has been identified in 4 to 17% of cases,^3,6,9 the reported rate is controversial and based on a small population.³ Nonetheless, complete resection with attention to the point of attachment is indicated to minimize recurrence, which has been reported at the rates of 33 to 40%,^3,10 necessitating careful long-term follow-up.

Glandular Tumors

Glandular tumors identified in the sinonasal tract are nearly all of salivary gland origin and are benign in 25%.6 Diagnosed in the third to seventh decades, pleomorphic adenoma demonstrates no sex preponderance and is thought to arise from minor salivary glands or ectopic rests of tissue and are primarily located in the submucosal tissues of the septum in 90% of cases,^6,11 though origin within the maxillary sinus¹² and lateral nasal wall¹³ has been reported. Several hundred cases of sinonasal pleomorphic adenoma have been reported,¹⁴ making this the most common benign sinonasal salivary gland tumor. Histologically, sinonasal pleomorphic adenomas appear similar to their major salivary counterparts with unencapsulated epithelial and myoepithelial ductal components in a chondromyxoid stroma, though reports have indicated that sinonasal tumors demonstrate less stromal component.¹² Surgical excision is indicated and curative, with recurrence rates of 5 to 7.5%.^11,13 Risk of malignant transformation is low and proportional to the length of time for which the tumor has persisted.¹² Additional salivary gland tumors reported less frequently in the sinonasal tract include myoepthelioma¹⁵ and oncocytoma.⁶ These are managed in a similar fashion.

Tumors of Bone, Cartilage, and Odontogenic Origin

Osteoma

Usually identified between the second and third decades,^2,16,17 osteomas demonstrate a male preponderance of 1.5:1 to 3:1. Osteomas are predominately identified in the frontal (60 to 70%)^2,18 or ethmoid (20 to 55%)¹⁶ sinuses, with a minority identified in the maxillary (less than 5%) and sphenoid (rare) sinuses.² Although histologically these tumors may exhibit an eburnated (ivory), spongy, or mixed appearance,^2,6,16 they have a characteristic radiodense, sharply demarcated appearance with polypoid or sessile projection of bone into the affected sinus^5,6,16 (Fig. 25.1). Osteomas are uniformly benign with no reports of malignant transformation,² so asymptomatic lesions may be followed with serial imaging. Resection is indicated if the tumor is symptomatic or at risk for becoming symptomatic because of its location and growth potential. Recurrence rates are very low.^2,6 Osteomas can be associated with Gardner syndrome, especially if multiple osteomas are identified. As only 7% exhibit multifocal osteomas in the absence of Gardner syndrome,¹⁶ the finding of multiple osteomas should trigger review of imaging to identify supernumerary teeth and referral for gastrointestinal evaluation to identify colonic polyposis, the third characteristic manifestation of Gardner syndrome.^1,2

Fibrous Dysplasia

Fibrous dysplasia (FD) is a neoplasm characterized by bone remodeling and can have disfiguring consequences. Presentation is location dependent, but it may include painless mass, nasal obstruction, epiphora, headache, pressure, vision changes, or cosmetic changes.^4,6,19,20 Monostotic FD is equally distributed between the sexes and six times more common than polyostotic FD, which has a 3:1 female predominance. FD is primarily a disease of youth, affecting patients in their second and third decades with three-quarters of cases diagnosed before 30 years of age.^2,4,6 Within the nose and sinuses, FD affects the maxilla with greatest frequency, followed by the frontal, sphenoid, and ethmoid bones.²⁰ FD demonstrates a characteristic ground-glass appearance on CT imaging¹ (Fig. 25.2A), and histologic findings of fibrous stroma with spindle cells and collagen fibers perpendicular to trabeculae of bone without osteoblastic rimming confirm the diagnosis.⁶ FD rarely undergoes malignant transformation (0.5% of polyostotic FD), typically in the setting of McCune-Albright syndrome.^2,6

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