Juvenile Nasopharyngeal Angiofibroma (JNA)

Overview

Pathology and Histology

• Numerous thin-walled vascular spaces lined by a single layer of endothelial cells, with no smooth muscle in the vessel walls (making them unable to constrict and explaining the severe, uncontrolled hemorrhage)
• These vascular channels are embedded in a dense collagenous fibrous stroma containing bland fibroblasts
• A mixed arterio-capillary component with muscularized channels also exists

Molecular Pathology

• CTNNB1 mutations (encoding β-catenin) are present in the majority of sporadic cases - activating the Wnt/β-catenin pathway
• JA can also arise syndromically in familial adenomatous polyposis (FAP), driven by germline APC mutations (also leading to β-catenin activation)
• Other molecular markers implicated: androgen receptor, bFGF, H-Ras, IL-6, c-Kit, c-Myc, PDGFa, TP53, VEGFA, and β-catenin show variable expression
• VEGF signaling and FGFR pathway are upregulated, suggesting angiogenic drive

Origin and Pathogenesis

Routes of Spread

Clinical Features

• Recurrent severe epistaxis - often massive and the presenting complaint; may cause anemia
• Nasal obstruction - progressive, usually unilateral at first
• Purulent rhinorrhea
• Facial swelling / "frog face" deformity (anterior bulging)
• Loss of vision - from compression of optic nerve by superior/orbital extension
• Conductive hearing loss (eustachian tube compression)
• Cheek anesthesia (V2 involvement in ITF extension)
• Intracranial extension: headache, cranial nerve palsies

Imaging

CT (Computed Tomography)

• Defines bony erosion and extent
• Widening of the pterygopalatine fossa - pathognomonic finding
• Erosion of the medial pterygoid plate
• Erosion in the region of the vidian canal aperture
• Anterior bowing of the posterior maxillary sinus wall

MRI (Magnetic Resonance Imaging)

• Defines soft-tissue extent and intracranial/orbital involvement
• Contrast-enhanced T1 shows diffuse or patchy enhancement
• Identifies dural enhancement suggesting intracranial spread
• Flow voids within the tumor on T2 (highly vascular lesion)

Pathognomonic radiological sign:

A nasal mass + widened pterygopalatine fossa in an adolescent male = pathognomonic for JNA

DSA (Digital Subtraction Angiography)

• Shows enlarged intratumoral vessels with a mixed pattern of arterioles
• Intense inhomogenous tumor blush in the venous phase showing full extent
• Blood supply primarily from external carotid artery branches (maxillary artery, sphenopalatine artery)
• If there is intracranial extension: internal carotid artery branches may contribute

Staging Systems

Management

Pre-operative Embolization

• Performed 24-48 hours before surgery (angiography + embolization in same session)
• Agents: PVA particles (transarterial) or NBCA/Onyx (transarterial or direct tumor puncture)
• Direct puncture with Onyx has improved the degree of devascularization
• Reduces intraoperative blood loss and tumor size
• Intracranial supply from ICA increases embolization risk (neurological deficit)
• For smaller, localized lesions - some centers now consider embolization unnecessary before endoscopic resection

Surgical Approaches

• Endoscopic resection - now preferred for Stages I-II and selected Stage III lesions (smaller tumors without significant spread)
• Midfacial degloving - allows ligation of the feeding maxillary artery; good exposure without facial scar
• Lateral rhinotomy - older open approach, still used for larger lesions
• Both open approaches allow ligation of the maxillary artery

Radiation Therapy

• Reserved for unresectable or recurrent disease, especially with intracranial extension
• Risk of radiation-induced malignancy in young patients limits its use

Hormonal Therapy

• Estrogen therapy has been used historically to reduce vascularity pre-operatively, but is largely abandoned due to side effects

Medical / Targeted Therapy

• Flutamide (anti-androgen) has been explored given androgen receptor expression
• Anti-VEGF agents (given VEGFA upregulation) are under investigation

Prognosis and Outcomes

• Recurrence rate: up to 20% after surgical resection
• Mortality: approximately 9% of cases can be fatal (from massive hemorrhage or intracranial spread)
• Spontaneous regression has been reported, particularly in older adolescents - consistent with the hormonal dependence theory
• Residual disease after surgery can be observed with imaging if it remains stable (no further growth mandate) - serial contrast-enhanced MRI is the standard follow-up modality

Key Points Summary

• Cummings Otolaryngology Head and Neck Surgery - JUVENILE ANGIOFIBROMA section (pp. 988-991)
• Robbins, Cotran & Kumar Pathologic Basis of Disease - Sinonasal Angiofibroma, p. 690
• Grainger & Allison's Diagnostic Radiology - Juvenile Angiofibroma (p. 1605)
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol. 1 - Juvenile Nasopharyngeal Angiofibroma
• Bailey and Love's Short Practice of Surgery, 28th Ed. - Angiofibroma, p. 9684

Juvenile Nasopharyngeal Angiofibroma (JNA)

Overview

Pathology and Histology

• Thin-walled vascular spaces lined by a single layer of endothelial cells with no smooth muscle in vessel walls - this is why bleeding is uncontrollable (vessels cannot vasoconstrict)
• Embedded in a dense collagenous fibrous stroma with bland fibroblasts
• Some authorities classify it as a vascular malformation / hamartoma rather than a true neoplasm

Molecular Pathology

Pathogenesis and Origin

Routes of Spread

Clinical Features

1. Recurrent severe epistaxis - uncontrolled, may cause anemia
2. Progressive nasal obstruction - usually unilateral initially
3. Purulent rhinorrhea

• Facial swelling / "frog face" deformity (anterior bulge of cheek)
• Visual loss - optic nerve compression from orbital/superior extension
• Conductive hearing loss (Eustachian tube obstruction)
• Cheek hypoesthesia (V2, from ITF involvement)
• Headache and cranial nerve palsies (intracranial extension)

Key pearl: These symptoms in a young male = always suspect JNA. Biopsy must be avoided unless imaging is non-diagnostic - risk of catastrophic hemorrhage.

Imaging

CT

• Defines bony erosion and tumor extent
• Widened pterygopalatine fossa - pathognomonic finding
• Erosion of the medial pterygoid plate
• Erosion at the vidian canal aperture
• Anterior bowing of the posterior maxillary sinus wall

MRI (with contrast)

• Best for soft-tissue extent, orbital, intracranial involvement
• Diffuse/patchy enhancement with contrast
• Flow voids on T2 (reflects high vascularity)
• Dural enhancement = intracranial spread
• Complements CT for preoperative planning

DSA (Digital Subtraction Angiography)

• Enlarged intratumoral vessels + intense inhomogenous tumor blush in venous phase
• Primary supply: ECA branches (maxillary artery, sphenopalatine artery)
• ICA contribution if intracranial spread present
• Used as part of pre-operative embolization

Nasal mass + widened pterygopalatine fossa in an adolescent male = JNA until proven otherwise

Staging Systems

Management

Step 1 - Pre-operative Embolization

• Performed 24-48 hours before surgery
• Transarterial: PVA particles or NBCA liquid embolic (for ECA-supplied tumors)
• Direct puncture: Onyx injection - improved devascularization, used when ICA involvement increases transarterial risk
• Goals: reduce intraoperative blood loss, induce tumor shrinkage, improve surgical access
• Smaller Stage I-II lesions: some centers now omit embolization before endoscopic resection
• ICA supply = higher risk of neurological deficit from embolization

Step 2 - Surgical Resection

Step 3 - Adjuvant Options

Prognosis

Quick-Reference Summary

Sinonasal Inverted Papilloma

Definition and Overview

• Incidence: 0.74 to 2.3 new cases per 100,000 per year; represents 0.4-4.7% of all surgically removed nasal tumors
• Sex: Male predominance - M:F ratio of 2-4:1
• Age: Most common in the 5th and 6th decades of life (middle-aged adults)

Types of Sinonasal Papilloma

These are distinct entities with different mutations: EGFR = inverted; KRAS = oncocytic. This distinction is preserved even in malignant transformation.

Histopathology

• Hyperplastic ribbons of multilayered epithelium grow inward in a bulbous, pushing pattern
• The epithelium is a mixture of squamous cells, ciliated columnar cells, and mucus-secreting (muco-cyte) cells, with transmigrating neutrophils
• A distinct, intact basement membrane is maintained throughout (distinguishes it from carcinoma)
• The surface is lined by thin respiratory epithelium while the underlying stroma contains multiple nodules of thick neoplastic epithelium growing inward

Molecular Pathology and Etiology

Key Molecular Drivers

HPV - The Controversy

Environmental Risk Factors

• Organic solvent exposure - significantly associated with IP (dose-response relationship)
• Smoking - not associated with development, but confers a 12-fold higher risk of malignant transformation (26.4% vs. 2.8% in smokers vs. non-smokers; p<0.001)
• Alcohol - no demonstrated association

Sites of Origin

Bilateral involvement of the frontal sinus is not uncommon (16%).

Clinical Features

• Unilateral nasal obstruction with watery rhinorrhea - most common symptom
• Unilateral chronic rhinosinusitis - headache, facial pressure/pain from sinus drainage obstruction
• Epistaxis (less common than in JNA)

• Epiphora (lacrimal obstruction)
• Proptosis and diplopia - orbital involvement; also raises suspicion for malignant transformation
• Invasion of orbit or cranial vault in locally aggressive cases

• Pale, polypoid mass with a papillary or cerebriform (brain-like) surface protruding from the middle meatus
• Coexisting inflammatory polyps may make diagnosis trickier
• Biopsy is required for definitive histology (unlike JNA where biopsy is avoided)

Imaging

CT

• Primary modality; defines bony involvement and extent
• Unilateral middle meatal mass with ostiomeatal pattern opacification
• Focal hyperostosis at the site of tumor attachment - useful for identifying the origin
• Calcification in 10% of cases at the attachment site
• Characteristic lobulated outline
• Bony thickening of sinus roof at insertion

MRI (with gadolinium)

• Superior to CT for differentiating tumor from retained secretions/inflammatory mucosa
• Cerebriform/columnar pattern on T1 gadolinium-enhanced MRI - pathognomonic for IP
  • Reflects alternating parallel folds of cellular metaplastic epithelium and less cellular stroma
• Best for assessing frontal sinus involvement (distinguishes tumor from obstructed mucus)
• Preferred for detecting recurrence (CT used for initial staging)

Malignant Transformation

• Overall rate: 5-15% (Cummings); Robbins cites up to 5%
• Synchronous carcinoma (present at time of IP diagnosis) is more common than metachronous (arising after initial treatment)
• Vast majority are squamous cell carcinomas (SCC)
• Rare associated malignancies: sinonasal undifferentiated carcinoma (SNUC), mucoepidermoid carcinoma, verrucous carcinoma
• Risk factors for malignant transformation:
  • Smoking (12x increased risk)
  • High-risk HPV subtypes (controversial)
  • Recurrent disease

Staging (Krouse Classification - most widely used)

Treatment

Principle

Surgical Approaches

Modern Trend - Pedicle-Oriented Resection

• Tumor debulked first to identify the stalk/origin
• Subperiosteal dissection + bone drilling limited to the attachment point only
• Equal recurrence rates to radical demucolization but shorter operative times and fewer complications

Recurrence and Follow-up

• Recurrence rate: 0-30% depending on approach; often due to residual disease rather than true recurrence
• HPV DNA in adjacent normal-appearing mucosa may contribute to recurrence (explains why complete field resection was historically advocated)
• Smoking is an independent risk factor for recurrence
• Follow-up: Regular nasal endoscopy + MRI (preferred over CT for detecting early recurrence)
• Endoscopic surveillance is the standard; CT used mainly for initial staging

Key Summary Table