Juvenile nasopharyngeal angiofibroma

Juvenile nasopharyngeal angiofibromas (JNA) are a rare benign but locally aggressive vascular tumour.

Epidemiology

Juvenile nasopharyngeal angiofibromas occur almost exclusively in males and usually in adolescence (~15 years). They account for only 0.5% of all head and neck tumours ², but are the most common of the benign nasopharyngeal neoplasms.

Clinical presentation

The presentation is typically with obstructive symptoms, epistaxis, and chronic otomastoiditis due to obstruction of the Eustachian tube. Patients may present with life-threatening epistaxis. On examination, it may be seen as a pale reddish-blue mass. It is, as the name suggests, very vascular and a biopsy can sometimes be fatal.

Pathology

Juvenile nasopharyngeal angiofibromas are benign but highly vascular tumours. They may be locally aggressive.

The exact site of origin is contentious as these masses usually present when they have reached considerable size. However, most authors agree that JNAs arise from the posterior choanal tissues in the region of the sphenopalatine foramen. 

Staging

See: staging of juvenile nasopharyngeal angiofibromas

Radiographic features

Imaging plays an important role in diagnosis, as biopsies should be avoided due to the risk of brisk haemorrhage, as well as staging.

Although these masses are thought to arise from the region of the sphenopalatine foramen, they are usually sizeable at diagnosis, frequently with extension medially into the nasopharynx, laterally into the pterygopalatine fossa and over time beyond, into the orbit, paranasal sinuses, intracranial cavity and infratemporal fossa. 

Plain radiograph

Plain radiographs no longer play a role in the workup of a suspected juvenile nasopharyngeal angiofibroma, however they may still be obtained in some instances during the assessment of nasal obstruction, or symptoms of sinus obstructions. Findings include ³: 

• visualisation of a nasopharyngeal mass
• opacification of the sphenoid sinus
• anterior bowing of the posterior wall of the maxillary antrum (Holman-Miller sign) ⁷
• widening of the pterygomaxillary fissure and pterygopalatine fossa
• erosion of the medial pterygoid plate

CT

CT is particularly useful at delineating bony changes. Findings are similar to those described above. Typically a lobulated non-encapsulated soft tissue mass is demonstrated centred on the sphenopalatine foramen (which is often widened) and usually bowing the posterior wall of the maxillary antrum anteriorly. There is marked contrast enhancement following administration of contrast, reflecting the prominent vascularity. 

Extensive bony destruction is usually not a feature, but rather bone is remodelled or resorbed. This feature may be helpful is differentiating from other more aggressive lesions. Intracranial extension can however occur.

Angiography (DSA)

Angiography, although not essential, is often useful in both defining the feeding vessels as well as in preoperative embolisation. Supply of these tumours is usually via ³:

• external carotid artery: majority
  • internal maxillary artery
  • ascending pharyngeal artery
  • palatine arteries
• internal carotid artery: less common, usually in larger tumours
  • sphenoidal branches
  • ophthalmic artery

Of note, enlargement of feeding vessels is not a common finding ⁶.

MRI

MRI is excellent at evaluating tumour extension into the orbit and intracranial compartments.

• T1: intermediate signal
• T2: heterogeneous signal: flow voids appear dark
• T1 C+ (Gd):  shows prominent enhancement

The presence of prominent flow voids lead to a salt and pepper appearance on most sequences and are characteristic ^5,6.

Treatment and prognosis

Surgical resection (either open or increasingly endoscopic) is the treatment of choice, usually performed with pre-operative embolisation to help with haemostasis. Irradiation may be an option if surgery is not possible or only incomplete resection achieved ^2,4,6.

In cases where there is skull base involvement a high recurrence rate (up to 50%) has been reported ^2,4.

Complications

• acute haemorrhage

Differential diagnosis

Imaging differential considerations include:

• angiomatous polyp: variant of a sinonasal polyp, located toward ostium/hardly extend to the nasopharynx, elderly age, less vascularity
• rhabdomyosarcoma (head and neck)
• nasopharyngeal carcinoma (NPC)
• nasopharyngeal teratoma
• nasopharyngeal lymphoma ¹⁰
• lymphangioma: no contrast enhancement
• encephalocoele: no contrast enhancement
• esthesioneuroblastoma