Inverted Papilloma of the Nose (Schneiderian / Ringertz tumour): 10-mark answer

Definition (1 mark)

Aetiology and pathology (1.5 marks)

• The cause is uncertain. HPV (types 6, 11, 16, 18) has been implicated, but its role is still debated. Cummings notes that studies using transcriptionally active HPV detection found it rarely, so HPV may be a colonizer.
• Exposure to organic solvents is a risk factor. Smoking is linked to recurrence and malignant change (Cummings Otolaryngology Head and Neck Surgery, Inverted Papilloma).
• Microscopy: ribbons of basement membrane-enclosed epithelium grow downward into the stroma. The epithelium is multilayered, made of squamous or ciliated columnar cells mixed with mucocytes and transmigrating neutrophils.
• The basement membrane is intact.

Incidence and site (1 mark)

• Men are affected more than women (about 2 to 3:1). It is most common between 40 and 70 years, and almost always unilateral.
• The usual site of origin is the lateral wall of the nose in the middle meatus. Less often it arises from the maxillary, frontal or sphenoid sinus.

Clinical features (1.5 marks)

• Unilateral nasal obstruction
• Nasal discharge
• Epistaxis
• Anosmia or facial pain, less commonly
• If it invades the orbit: proptosis, diplopia and epiphora (lacrimation)

• Simple nasal polyp (usually bilateral, translucent and not friable)
• Antrochoanal polyp
• Angiofibroma
• Malignancy
• Fungal sinusitis

Investigations (2 marks)

1. Diagnostic nasal endoscopy.
2. CT scan. It shows a unilateral soft tissue mass in the middle meatus and maxillary sinus. Bone remodelling, erosion and focal hyperostosis at the site of origin are seen (Scott-Brown, Fig. 117.13).
3. MRI. It shows the extent of the lesion and separates tumour from retained secretions. The convoluted cerebriform pattern on T2 and post-contrast images is highly suggestive of IP. Necrosis suggests a coexisting carcinoma (Scott-Brown's Otorhinolaryngology, Specific Types of Neoplasms).
4. Biopsy confirms the diagnosis. Take multiple, deep biopsies to exclude associated carcinoma.

Staging (0.5 mark)

• T1: confined to the nasal cavity.
• T2: ethmoid sinuses and/or medial and superior maxillary sinus.
• T3: lateral, inferior, anterior or posterior maxillary wall, or sphenoid or frontal sinus.
• T4: extension outside the sinonasal tract, or any malignancy.

Treatment (2 marks)

• Medial maxillectomy is the standard operation. It can be done by:
  • lateral rhinotomy (Weber-Ferguson incision)
  • sublabial degloving approach
  • the endoscopic approach, which is now preferred for most tumours.
• Wider external approaches are needed for tumour extending to the frontal sinus or orbit.
• Tumour with carcinoma needs craniofacial resection or radical surgery, with postoperative radiotherapy.
• Radiotherapy is not advised for benign IP because it may induce malignancy.
• Follow-up is long term with endoscopy and imaging, because recurrence is common.

Complications and prognosis (0.5 mark)

• Recurrence is common, up to about 20%. It is usually due to incomplete removal.
• Malignant transformation, mostly to squamous cell carcinoma, occurs in about 5 to 15% of cases (Cummings).
• Local invasion of the orbit and skull base can occur.

Diagram for the exam

Key points to memorise

• Unilateral polyp in a man aged 40 to 70 is IP until proven otherwise.
• Cerebriform pattern on MRI.
• Medial maxillectomy.
• No radiotherapy.
• Risk of malignancy, 5 to 15%.