The maxillary sinus of the face is the most prominent paranasal sinus and has a volume of 10 milliliters (ml). It acts as a protective covering for the face, helps in the resonance of the voicebox, and reduces the weight of the facial skeleton.
Inverted papilloma is a non-cancerous (benign) tumor of the maxillary sinus. It is a commonly occurring benign tumor with the potential for local invasion and malignant transformation. It mainly affects middle-aged men (40 - 60 years) and has a higher prevalence in males than females (with a male-to-female ratio of 3.5:1).
What Are the Clinical Features of Inverted Papillomas?
Inverted papilloma is similar to many other lesions of the sinonasal (tumors that occur in the nasal cavity or nasal sinuses) cavity. Some of the following clinical features can be seen in these tumors -
Patients frequently complain of nasal obstruction.
Patients feel pain in the sinus region on the face.
Epistaxis or nasal bleeding may be a frequent observation by the patient.
Some patients may show severe nasal congestion without experiencing any of the above-mentioned signs. Also, they may experience changes in the sense of smell (anosmia) over time, accompanied mainly by facial pain.
What Is the Potential of Inverted Papillomas for Local and Malignant Spread?
The majority of inverted papillomas are non-malignant or benign lesions. But approximately 5 - 15 % of cases of inverted papillomas may give rise to common forms of skin cancers such as
squamous cell carcinomas. In addition, inverted papillomas may not distantly metastasize to other body organs. Although, they tend to be highly aggressive with the potential for local spread, specifically in the nasopharynx, cranial base, orbit or middle ear.
Since the lesion always grows inwardly, inverted papillomas cause invasive bone destruction around the paranasal sinuses. They may also impact the region of the orbit (eyes) and the spaces between the brain and the facial sinuses. This may be life-threatening in the long term, especially when they are not diagnosed correctly or left untreated.
How Can Inverted Papillomas Be Diagnosed?
Inverted papillomas can be diagnosed using imaging modalities such as MRI (magnetic resonance imaging) and CT (computed tomography). These methods can be used to visualize the masses in the maxillary sinus more accurately. For example, in MRI imaging, these masses may present as a convoluted cerebriform pattern in T1 and T2 contrast weighted images which is a diagnostic sign of inverted papilloma.
What Is the Differential Diagnosis of Inverted Papilloma?
Diagnosing inverted papillomas is challenging for dentists as they resemble many other lesions. Also, they resemble other lesions of sinonasal regions, either with or without polypoid masses, which include
Lesions or masses of the nasal cavity and middle meatus.
Conditions like chronic rhinosinusitis.
Antrochoanal polyp or Killian polyp of the maxillary sinus.
Certain undefined polyp lesions, such as isolated nasal polyps.
Benign or malignant tumors of the sinonasal area (certain cancerous or malignant tumors may have the ability to mimic commonly occurring inflammatory lesions).
Other sinonasal papillomas.
What Is the Management of Inverted Papillomas?
Inverted papillomas of the maxillary sinus are diagnostically challenging because they resemble sinonasal diseases of other origins. Also, these lesions require an adequate and extensive surgical approach for excision.
Some of the methods that can be used to remove this tumor are -
1. Medial Maxillectomy-
Surgeons may recommend the surgical procedure known as classical medial maxillectomy in cases where it is tough to approach the papilloma through direct methods. In this procedure, the medial wall of the maxillary sinus is resected along with the inferior turbinate and nasolacrimal duct to remove the tumor completely.
Other traditional surgical methods such as transoral sublabial access or Caldwell-Luc procedure and Canine-fossa-trephination can also be used.
2. Conservative Endoscopic or Endonasal Prelacrimal Surgical Approach -
Nowadays, surgeons mostly use the approach through the endoscopic technique (the conservative endoscopic or endonasal prelacrimal surgical approach to the sinus) to excise the tumor. In addition, it improves the long-term prognosis and helps preserve the inferior turbinate and the nasolacrimal duct.
Inverted papilloma of the maxillary sinus is a benign yet aggressive lesion. Prompt diagnosis and conservative treatment approach offer a better prognosis and minimize the possibility of recurrence or malignant transformation.