RADIOLOGICAL FEATURES OF JUVENILE NASOPHARYNGEAL ANGIOFIBROMA

Abstract

Juvenile nasopharyngeal angiofibroma is a rare nasopharyngeal tumour that presents with recurrent epistaxis. A case report and the role of radiologic imaging modalities in diagnosing this entity is presented.

Introduction

Juvenile nasopharyngeal angiofibroma is an uncommon benign tumour of the nasopharynx which arises in the region of the sphenopalatine foramen and it grows insidiously invading surrounding structures. It was first described by Hippocrates in the 5^th century BC. It was Friedberg who first used the term angiofibroma in 1940. It is the commonest benign tumour of the nasopharynx but accounting for 0.5% of all head and neck tumours1. It is a vascular tumour and believed to affect males exclusively. It presents commonly with nasal obstruction and recurrent epistaxis in young adolescent males. It presents in the second decade of life within the age range of 5-25 years. The nasopharynx is not easily accessible but has a high capacity and as such, tumours in this region tend to present late. Making a diagnosis of this condition requires a high index of suspicion as it mimics other sinonasal conditions and approaching it as such may result in fatal outcome. We present a case of a 15 year old male with juvenile nasopharyngeal angiofibroma and discuss the steps necessary for radiological diagnosis.

Case Report

A.H was a 15 year old male who presented with a 2-year history of nasal obstruction and recurrent nasal bleeding. He had had about ten episodes of epistaxis in the last year. The most recent episode lasted for a duration of 5 days and required hospital admission as against previous episodes which usually resolved with minimal intervention. Examination revealed a young man who was not acutely ill looking but anxious. He was not pale and other vital signs were essentially with normal limits. The nasal cavity revealed fresh blood in both nasal cavities but the bleeding site could not be visualized. There was no nasal secretion and there was no area of tenderness on the face. The palate appeared tented but no mass was visualized in the oropharynx. An impression of epistaxis secondary to rhinosinusitis was made; plain radiograph of the paranasal sinuses showed an opaque mass in the post nasal space but the sinuses were clear.

The CT scan of the nasopharynx revealed a markedly contrast enhancing lesion measuring 4.0cm by 3.7cm by 2.5cm in the posterior nasal space and nasopharynx with complete occlusion of the adjacent airway as shown in Figure1. There was mild erosion of the medial aspect of the medial pterygoid bone and the base of the left sphenoid sinus with a little extension of the mass into it (Figure 2). A radiological diagnosis of juvenile nasopharyngeal angiofibroma (JNA) was made. The patient was referred afterwards to a hospital in India where he had pre-operative embolization and endoscopic excision. The mass was found to extend from the nasopharynx to the left pharyngopalantine fossa and left sphenoid sinus with an extra axial extension intracranially into the medial temporal region. Histopathological examination of the specimen showed a polypoidal tumour composed of spindle cells with many scattered dilated capillaries lined by endothelial cells no malignant cells were seen.

A diagnosis of angiofibroma was subsequently made.

Figure 1 .

Contrast enhanced axial CT scan of the nasopharynx showing contrast enhancing mass in the posterior nasal space and nasopharynx with occlusion of the adjacent airway.

Figure 2 .

Axial CT of the nasopharynx (bone window) showing mild erosion of the medial aspect of the left medial pterygoid bone

Discussion

Juvenile nasopharyngeal angiofibromas (JNA) is an uncommon histologically benign but locally aggressive vascular tumour, accounting for 0.05% of all head and neck tumours1, but are the most common of benign nasopharyngeal tumours2. As the name implies, JNA is a disease of the young and occurs almost exclusively in adolescent males. It can occur in the second decade usually between the ages of 5 and 25 and a mean age of 15 years2. The index patient was a 15-year old male.

The male preponderance of JNA has been explained by genetic studies which showed the close relationship between these angiomas and androgen receptor expression, demonstrated by the presence of androgen, testosterone, and dihydrotestosterone receptors, and the lack of estrogen and progesterone receptors indicating that this tumor is possibly androgendependent2,3.

Patients commonly present with obstructive nasal symptoms, recurrent epistaxis and nasopharyngeal mass as seen in this case report. Other symptoms may include hard and soft palate deformity, chronic otomastoiditis, hearing loss, dacrocystitis, hyposomia or anosomia while advanced lesions may cause facial swelling, proptosis, neuropathy of cranial nerves and massive haemorrhage3.

Furthermore, rhinoscopy may reveal a pale reddish blue mass2. Biopsy of JNA can produces significant life threatening haemorrhage and as such should be avoided. Imaging techniques play an important role in diagnosis as well as staging of JNA since it exhibits a characteristic appearance on imaging that often makes obtaining a biopsy unnecessary. With infratemporal involvement, JNA produces a thinning and anterior bowing of the posterior wall of maxillary sinus (Holman miller sign)2, other signs of tumour erosion include displacement of the hard palate and erosion of the medial pterygoid plate and orbital fissure enlargement4. Erosion of the medial pterygoid was evident on the CT scan of our patient. Such a diagnostic approach should be borne in mind given the potentially high risk for significant hemorrhage from such neoplasms. The site of origin of JNA can either be from the sphenopalatine foramen which communicates between the nasal cavity and the pterygopalatine fossa or from the vidian (pterygoid) canal, though these theories are known to be controversial2,3.

Though plain radiographs are likely to be obtained as preliminary investigations, cross sectional multiplanar CT and MRI clinch the diagnosis of JNA. Angiography is also diagnostic and also has an interventional role. Plain films of the paranasal sinuses are the first line of investigation for sinonasal pathology, the radiographic findings1,3 may include demonstration of the nasopharyngeal mass which may extend into the pterygopalatine fossa resulting in widening of the pterygopalatine fossa and anterior bowing of the posterior wall of the ipsilateral maxillary antral wall4. The lateral view of the plain radiograph of the skull may demonstrate opacification of the sphenoid sinus which may spread to also include the maxillary and ethmoid sinuses. Another plain film finding is widening of the inferior and superior orbital fissures which is an indication of spread into the orbit and intracranial extension.

Computed Tomographic findings similar to those described for plain film features are clearly demonstrable with better resolution. JNA is demonstrable as an avidly enhancing lobulated non-encapsulated soft tissue nasopharyngeal mass on CT scan following intravenous administration of contrast medium reflecting its characteristic vascularity. This was observed on the scan of the index patient. Intraorbital and intracranial extension is also better demonstrable. There was however no intracranial extension of JNA in our patient. Bone window setting highlights the important advantage of CT imaging in its superiority in evaluating bony details compared to plain films and magnetic resonance imaging (MRI), and this is best exemplified with an anterior bowing to the posterior maxillary sinus wall that JNA is commonly associated with5 and is referred to as the Holman-Miller sign3. Widening of the sphenopalatine foramen may also be observed. Bony erosion is common as also seen in the patient presented. Extensive bony destruction may also be seen especially in advanced disease.3

MRI because of its better soft issue characterization in comparison to CT is able to delineate mucosal inflammation versus sinus fluid. It is also valuable at evaluating tumour extension into the orbit and intracranial compartments and is accurate in tumour staging. JNA is of intermediate signal intensity and heterogenous signal intensity on T1 and T2 weighted spin echo sequences respectively. Multiple flow voids will also be seen within the tumour on both sequences. Just as with CT scanning, following intravenous administration of Gadolinium, JNA shows prominent enhancement, again demonstrating the vascularity of this benign tumour5. The presence of prominent flow-voids seen on MRI scans represents enlarged tumour vessesls2. MR imaging also better delineates spread in the region of the cavernous sinus and into the middle cranial fossa2.

Angiography is useful in identifying and defining the major feeding vessels which are commonly the internal maxillary artery and the ascending pharyngeal artery 2. Angiography is also useful in preoperative embolization to aid subsequent surgery. The rationale is that occluding the responsible artery from which the JNA originates will decrease intraoperative blood loss and even decrease the tumor size to augment resection of the tumour. Preoperative embolization is generally undertaken 24-72 hours prior to resection and often employs either gelfoam or polyvinyl alcohol foam. A number of studies support the role of embolization in reducing intraoperative blood loss6,7. However, Moulin et al6 reported statistical significance of this occurrence mainly for larger staged tumors while Liu et al7 noted similar findings only for smaller ones limited to the nasal cavity or nasopharynx. Despite its utility in managing JNA, angiography may not be a required diagnostic endeavor and surgical excision may still be performed in its absence5,8.

Conclusions

Juvenile nasopharyngeal angiofibroma is an uncommon condition occurring in adolescent males which requires a high index of suspicion to diagnose. Characteristic signs on radiologic imaging modalities help to confirm diagnosis as biopsy stands the risk of fatal haemorrhage.