Inverted Papilloma

ByA. Mendelson, MD
Please read the disclaimer

An inverted papilloma is a type of benign tumor that often arises in the nasal cavity or sinuses. Although not cancer, it has a tendency to grow aggressively and recur, and in rare cases, it can turn into cancer. If your radiology report mentions “inverted papilloma,” it typically means a mass was found in the nasal or sinus region that has imaging features suggesting this type of tumor. A CT or MRI scan is usually the key step in identifying and evaluating this finding.

What Is an Inverted Papilloma?

An inverted papilloma is a growth that comes from the lining of the nasal cavity or the sinuses. It grows inward into the surrounding tissues, which is why it’s called “inverted.” While the tumor is non-cancerous in most cases, it has a known risk of coming back after treatment and can occasionally transform into squamous cell carcinoma.

Symptoms That May Lead to Imaging

Patients may experience:

  • Nasal obstruction or congestion

  • Frequent nosebleeds

  • Sinus infections

  • Loss of smell

  • Facial pressure or pain

These symptoms may prompt a doctor to order a CT scan or MRI to investigate further.

CT Scan Features of Inverted Papilloma

A CT (computed tomography) scan uses X-rays to create detailed images of your sinuses and nasal structures. Radiologists often look for:

  • A unilateral (one-sided) mass in the nasal cavity or sinus

  • Sinus opacification (cloudy appearance inside the sinus)

  • A mass that may extend into nearby sinuses or cause expansion

CT is helpful in assessing the bony anatomy and the extent of sinus involvement, but it cannot confirm the diagnosis on its own.

MRI Findings of Inverted Papilloma

MRI (magnetic resonance imaging) uses magnetic fields to provide better soft tissue contrast than CT. It is especially useful when evaluating a suspected inverted papilloma. Radiologic features often include:

  • A lobulated mass with a characteristic “cerebriform” (brain-like) pattern on T2-weighted and contrast-enhanced T1-weighted images

  • Moderate to strong enhancement after contrast administration

  • Extension into adjacent tissues like the orbit or cranial cavity, if advanced

  • Helps differentiate between tumor and retained mucus

MRI is often used in surgical planning to map out the tumor’s full extent and avoid leaving behind residual tissue.

Diagnosis and Biopsy

Although imaging can strongly suggest inverted papilloma, a biopsy is necessary to confirm the diagnosis. Often, this is done through nasal endoscopy. Histology shows characteristic inward growth of the epithelial cells, giving it the name “inverted.”

Risk of Malignant Transformation

Up to 15% of inverted papillomas may transform into cancer, most commonly squamous cell carcinoma. This is why radiologists and ENT surgeons take these tumors seriously. Imaging helps monitor for any suspicious features such as:

  • Irregular or destructive bone changes

  • Invasion beyond expected boundaries

  • Heterogeneous or necrotic appearance on MRI

If these features are seen, further evaluation and sometimes additional biopsies are recommended.

Treatment Options

Surgical removal is the mainstay of treatment. This is typically done using endoscopic sinus surgery. Complete removal is crucial because recurrence rates can be high if any tissue is left behind. Imaging helps the surgeon plan the operation.

Post-surgery, regular imaging follow-up with MRI or CT is often recommended as recurrence can happen even after what seems to be successful surgery.

Follow-Up Imaging

MRI is preferred for follow-up due to its ability to detect subtle recurrences in soft tissue, especially near the surgical site.

Common Misinterpretations

It’s easy to confuse inverted papilloma with other benign or malignant sinus tumors on imaging. Mucoceles, fungal sinusitis, and polyps can appear similar, especially on CT. MRI helps distinguish between these entities using tissue contrast and enhancement patterns.

Why Imaging Matters

Radiology plays a central role in:

  • Identifying the lesion

  • Differentiating it from other masses

  • Planning surgical treatment

  • Detecting recurrence

  • Assessing potential transformation into cancer

Conclusion

If your radiology report mentions an inverted papilloma, it means a mass has been found that shows features of this tumor. While not usually cancerous, it requires surgical removal and long-term follow-up due to its potential to recur or, in rare cases, become malignant. CT and MRI are essential tools in diagnosis, treatment planning, and post-operative surveillance. Always follow up with your ENT specialist for further care.

References

https://pubmed.ncbi.nlm.nih.gov/26632214/

https://radiopaedia.org/articles/inverted-papilloma

https://journalotohns.biomedcentral.com/articles/10.1186/s40463-020-00420-x

Disclaimer: The content of this website is provided for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.

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