20.1 Introduction and Epidemiology

Juvenile nasopharyngeal angiofibroma (JNA) is a highly vascular, benign, yet locally aggressive tumor with a propensity toward skull base erosion and intracranial extension. Early description of this neoplasm was given by Hippocrates in the 4th century BC. In 1878, Bensch first elaborated the morphological and clinical features of JNA. ¹ It was Chaveau in 1906 who suggested the term “juvenile nasopharyngeal angiofibroma.” ²

JNA is noted to be the most common benign tumor originating in the nasopharynx. ³ Biswas et al reported JNA as one of the most common benign otolaryngological tumors. ⁴ In accordance with available literature, JNA accounts for 0.05 to 0.5% of all head and neck neoplasms. ^{5 ,​ 6} The incidence of JNA is approximately 1/150,000 and almost exclusively affects adolescent males between the ages of 10 and 25 years. ^{7 ,​ 8} It is agreed that the incidence of JNA is higher in the Indian subcontinent and Egypt than in the United States and Europe. Furthermore, a study conducted by Mishra and Mishra states that India harbors the maximum burden of the disease, with a fourfold increase in incidence in the last decade. ⁹

This chapter reviews the endoscopic approach to this formidable tumor and summarizes pertinent literature with respect to its evolving management. The approaches described in the chapter are based largely on the author’s experience in managing an extensive series of nasal angiofibroma patients for more than two decades. The emphasis is on a thorough understanding of tumor extensions on imaging, pathways of spread, and endoscopic approaches to curtail perioperative mortality, as well as on achieving better surgical outcomes.

20.2 Natural History

It is proposed that after its intradiploic origin, JNA tends to spread submucosally along certain pathways. It is observed that the tumor commonly follows an anterolateral or less commonly, a posterior pathway. The anterior pathway of spread is from the nasopharynx to the sphenoid sinus superomedially and through the pterygopalatine fossa to the infratemporal fossa laterally. From here, the tumor takes multiple directions: superiorly to the temporal fossa, inferiorly to the parapharyngeal space, and laterally to the cheek (▶ Fig. 20.1a). In the less common posterior pathway, the tumor spreads to the quadrangular space extending to Meckel’s cave and then to the cavernous sinus (▶ Fig. 20.1b). It is vital to extirpate the tumor surgically from all these extensions to avoid recurrence. Though spontaneous regression is noted in a few cases with postoperative residual tumors, the factors governing this behavior are still under investigation.

20.3 Clinical Assessment

Most commonly, JNA declares itself with gradually progressive painless nasal obstruction with intermittent unprovoked epistaxis. As a dictum, any adolescent male presenting with epistaxis should be subjected to endoscopic examination to rule out JNA.

Prolonged obstruction can cause sinusitis, headache, and hyposmia. Eustachian tube blockage by the mass can present with complaints of ear pain, effusion, and conductive hearing loss. The tumor may push the soft palate, protrude in the oral cavity, or extend into parapharyngeal space, causing difficulty in speech and swallowing.

Patients with advanced tumors extending posteriorly to the nasopharynx present with mouth breathing, snoring, and rhinolalia clausa (hypernasal speech).

The tumor extending anteriorly can obstruct the nasolacrimal duct and can cause dacryocystitis (infection of the lacrimal sac) and spread to the cheek, which can lead to a typical “frog face” facial deformity. Superior extension and invasion of the orbit lead to proptosis and diplopia in extreme gaze due to compromised space. Extension into the cavernous sinus can, albeit rarely, present with cranial nerve palsies (third to sixth cranial nerves).

A thorough general and otorhinolaryngological examination along with an examination of cranial nerves should be performed. On inspection of the face, swelling may be evident in the cheek or temporal fossa. The oral cavity should be examined for trismus or bulge in the soft palate. A 2.7-mm scope is preferred for nasal endoscopy in pediatric patients. It reveals a smooth, reddish, and lobulated mass in the nasopharynx. The patients should never be subjected to biopsy if JNA is suspected.

20.4 Imaging

Preoperative imaging is an integral part of workup for the diagnosis and management of JNA. Accurate preoperative imaging is essential for determining the extensions of the disease. CT scan forms the basis for the staging system of JNA and has prognostic significance. The osseous details, such as bone erosion and widening of foramen and fissures, are detected in CT scan bone windows. In the soft tissue and intermediate windows, contrast-enhancing extensions of the tumor should be studied at intervals as thin as 0.625 mm in both axial and coronal planes. Coronal CT images are preferred for evaluating the stage of the tumor, showing the relationship of the tumor to the vital structures, and choosing a surgical approach for providing adequate exposure.

A typical finding in a contrast-enhanced CT (CECT) scan is a lobulated nonencapsulated enhancing mass in nasopharynx and pterygopalatine fossa following administration of contrast. Lloyd et al ¹⁰ described the following three characteristic features suggesting a diagnosis of JNA:

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  A soft-tissue mass in the nasopharynx and the nasal cavity.

  
  
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  A mass in the pterygopalatine fossa.

  
  
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  Erosion of the posterior osseous margin of the sphenopalatine foramen extending to the base of the medial pterygoid plate. The “Holman–Miller” sign represents anterior bowing of posterior maxillary wall on axial CT sections.

20.4.2 Significance of the Pterygoid Wedge

The pterygoid wedge is defined as a triangular area at the anterior junction of the lateral and the medial pterygoid plates. The involvement of the pterygoid wedge was observed in 99.1% of our preoperative images. The characteristic widening of the pterygoid wedge to a quadrangular appearance was observed in our cases consistently and was coined the “RAM HARAN” sign (▶ Fig. 20.2). In advanced cases and revision cases, this sign is not encountered due to bone destruction and surgical resection, respectively.

In the authors’ series of 242 cases, it was observed that the average width of the pterygoid wedge of the involved side was approximately twice that of the uninvolved side. The pterygoid wedge was involved in 99.1% of our series, even in the earliest stages where other proposed sites of inception remained uninvolved. The pterygoid wedge was observed as the epicenter of the tumor.

At the authors’ center, early postoperative evaluation included a CECT scan done after 36 hours of surgery to identify any residual tumor. It is of vital importance to assess any residual tumor in the soft-tissue window. Complete removal of the tumor is confirmed by the absence of enhancing areas in the sinonasal cavity or the nasopharynx. Another interesting finding seen in postoperative coronal scans was the typical appearance imparted by the interrelation of the medial and lateral pterygoid plates. Owing to complete removal of the pterygoid wedge, the pterygoid plates are seen as two parallel lines. This characteristic appearance was consistently noted by the authors in their series (▶ Fig. 20.3). Though MRI is superior in evaluating postoperative recurrence as it delineates soft tissues better, it can sometimes be misleading, showing fibrosis as contrast enhancement, and is more prone to motion artifacts.

On MRI, the tumor shows a characteristic “salt and pepper” appearance, which is given by the tumor and the flow void areas, respectively. There can be several flow voids, owing to the tumor’s highly vascular nature. The lesion characteristically shows low to intermediate signal intensity on T1-weighted images. On T2-weighted images, heterogeneous intermediate signal intensity is seen in the tumor mass, with flow voids appearing as dark areas, and in contrast-enhanced MR images, avid enhancement especially with T1-weighted images. MRI is even more important postoperatively to show any residual or recurrent tumor and monitor the effects of radiotherapy. ¹³

Digital subtraction angiography (DSA) is useful in defining both the feeding vessels and preoperative embolization. Residual tumor vascularity after embolization is employed as a criterion to stage JNAs in the University of Pennsylvania Medical Center (UPMC) classification system. ¹⁴ At our center, JNAs with feeders from the internal carotid artery (ICA) system are identified preoperatively. Such JNAs may have to be subjected to multiple-stage operations.

Preoperative embolization of JNA has shown to decrease intraoperative blood loss and operative time. Preoperative embolization is generally done 24 to 48 hours before the surgical procedure to avoid chances of revascularization. Even with newer agents, embolization is associated with risks like cranial nerve injuries, stroke, and blindness. The benefits of embolization should be gauged against risks of neurological complications.

20.5 Staging System

Staging is vital to describe the extent of tumor, facilitate decision-making regarding management protocol, and prognosticate outcome. An ideal staging system for JNA should provide information regarding prognosis, treatment options, anticipated blood loss, and possible complications that may ensue.

The first staging system for JNA was proposed by Sessions et al in 1981. ¹⁵ It was based on anatomical location and was similar to that used for nasopharyngeal carcinoma. Many modifications in classifications were described by Chandler et al, ¹⁶ Fisch, ¹⁷ Bremer et al, ¹⁸ and Andrews et al. ¹⁹ The most accepted classification was Radkowski et al’s classification, which was a modification of Session’s classification. ²⁰ It described that the skull base extension was associated with higher levels of recurrence. It differentiated between minimal skull base erosion, minimal intracranial extension, and massive intracranial extension.

In the past decade, the endoscopic approach has emerged as an alternative to the external approach due to reduced morbidity and reduced recurrence rates. Based on advancement in imaging technology and expanded use of endoscopes, a new staging system was proposed by Onerci et al in 2006, ²¹ introducing endoscopes as a viable alternative. Snyderman et al ¹⁴ noted two important factors: route of skull base extension and residual vascularity after embolization to predict prognosis in angiofibroma patients, and proposed an endoscopic staging system for JNA. They noted that tumor size and extent of disease are less important in predicting complete tumor removal.

We have formulated a staging system that relies on tumor extensions on preoperative CECT imaging. This system emphasizes stratifying patients based on preoperative imaging into stages and proposes a tailor-made surgical approach for each stage (▶ Table 20.3). In our study, limits of the single-corridor, transnasal endoscopic approach were explored. In limited cases, an endoscopic multicorridor approach was employed to be minimally invasive. The tumors beyond that were managed by open approaches. The reproducibility of this staging system depends on the experience and skill of the surgeon. The various staging systems are elaborated in ▶ Table 20.1 .

20.6 Endoscopic Approach

Different viewpoints about optimal surgical approaches are discussed in the literature. The very fact that numerous approaches were developed to access angiofibromas confirms the inaccessibility of this lesion. Moreover, JNA has a high propensity of postoperative recurrence, especially in areas that are surgically difficult to access. The introduction of endoscopes has improved visualization and surgical access in otorhinolaryngological disorders. The first endoscopic excision of JNA was performed by Reida Kamel in 1996. Since then, technical advancements and growing surgical expertise are constantly expanding the limits of endonasal endoscopic JNA surgery. Owing to better surgical outcomes, this corridor has now evolved as a preferred approach for small and medium-sized tumors.

20.7 Principles

Principles and philosophies of endoscopic approach should be followed to ensure better outcomes and results in comparison to conventional techniques.

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13 Sellar Arachnoid Cysts 16 Craniopharyngioma 21 Optic Pathway Glioma and Juvenile Pilocytic Astrocytoma 23 Chordoma 25 Malignant Skull Base Tumors 26 Subperiosteal Orbital Abscess

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