Solitary polyps of the uncinate process.

Abstract

Cases of a solitary polyp of the nasal cavity are much less common than cases of massive polyposis. The most important factor in the formation of solitary polyps is the anatomic variations that result in mucosal contacts. We report the case of a patient who had bilateral solitary polyps of the uncinate process. Radiologic and clinical examinations revealed a medially bent uncinate process in the right nasal cavity and a bifid uncinate process in the left nasal cavity. These structures were the origins of the polyps.

Introduction

Nasal polyps can arise in the form of solitary lesions or massive polyposis. The most common sites of origin for nasal polyposis are where the uncinate process, the middle concha, and the ethmoid bulla are in contact with each other. (1) Various theories and causal factors have been proposed to explain the formation of nasal polyps--including chronic infection, allergy, aspirin intolerance, cystic fibrosis, and ciliary dyskinesia--but the exact etiology of these lesions is unknown. (2) Whatever the initial cause, if the stimulus persists, the resultant mucosal swelling and edema can lead to polypoid degeneration of the mucosa. (1)

We report an unusual case of bilateral solitary polyps in which the lesions originated in the uncinate process. Increased exposure to irritants by the uncinate process and contact between the mucosal surfaces of the uncinate process and the middle conchae were thought to have led to the development of both lesions.

Case report

A 76-year-old man presented with a 3-month history of headache and nasal obstruction. Findings on anterior rhinoscopic examination were unremarkable. Endoscopy detected a single, pale, pedunculated, polypoid mass in each nasal cavity (figure 1). Both polyps originated in the middle meatus and obstructed the osteomeatal complex, and the mass on the right extended to the choana. Computed tomography (CT) of the paranasal sinuses demonstrated a solitary polypoid mass in the middle meatus bilaterally (figure 2). CT also detected maxillary sinusitis and concha bullosa on both sides and a bifid uncinate process on the left. The patient had no history of systemic disease (e.g., allergy, diabetes mellitus, aspirin intolerance, ciliary dyskinesia, etc.), and the results of allergy skin testing were negative. The diagnosis was a solitary polyp in each nasal cavity.

[FIGURES 1-2 OMITTED]

Endoscopic sinus surgery was performed, and both polyps were removed via uncinatectomy. Examination during surgery revealed that the polyp on the right had originated in a medial bend in the uncinate process and the polyp on the left had originated in the bifid uncinate process. Mucoid secretion was aspirated from each maxillary sinus ostium. The mucosal lining of both maxillary sinuses appeared to be normal.

Histopathologic examination of each polyp specimen revealed intact surface epithelium made up of respiratory epithelium (figure 3). The stroma was markedly edematous and was infiltrated by chronic inflammatory cells--predominantly eosinophils, plasma cells, and lymphocytes. These findings were compatible with a nasal polyp.

[FIGURE 3 OMITTED]

The patient's headache and nasal obstruction resolved during the first week after surgery, and he had experienced no recurrence at the 5-month follow-up.

Discussion

The mechanism by which solitary nasal polyps and nasal polyposis develop is unknown, and the issue is controversial. However, it is well known that the osteomeatal complex--especially that portion that faces the ethmoid infundibulum, which is sensitive to the polypoid transformation of the mucosa--is usually involved in the pathogenesis of nasal polyposis. (1) Although the uncinate process is one of the most common sites affected by nasal polyposis, it is rare for a solitary polyp to arise from this structure. (1,3) Systemic factors such as chronic infection, allergy, aspirin intolerance, cystic fibrosis, and ciliary dyskinesia are all known to be important in the pathogenesis of nasal polyposis. (2) However, the mechanism of the formation of solitary polyps of the uncinate process without involvement of the osteomeatal complex might not be explainable by systemic factors only. Local factors--specifically, anatomic structures or variations that alter airflow and cause mucosal contacts--might be much more important in the formation of solitary nasal polyps. (1)

The uncinate process is a shield-like formation that protects the ethmoid infundibulum from direct exposure to airflow. The anterior surface of the uncinate process is the surface that is probably most exposed to airflow. Air-borne irritants that pass into the nose can trigger inflammation, which usually occurs on the surface that has the greatest exposure. It follows that the anterior surface of the uncinate process is the most likely surface to be affected. If variations of the uncinate process increase the anterior surface area (as occurred in our case), this situation may result in increased exposure to irritants and create conditions that promote polypoid transformation of the mucosa. The variations in the uncinate process, which result in mucosal contact between the uncinate process and the middle concha, can also predispose to polypoid transformation. (1) We speculate that the trigger mechanism for the formation of solitary polyps might be local factors, such as increased exposure of irritants and/or mucosal contact, instead of systemic factors, which result in disseminated nasal polyposis.

The uncinate process is a delicate shelf that attaches laterally and extends posteriorly to the inferior concha. (1) The upper part of the uncinate process may attach solely to the lamina papyracea, the cribriform plate, or the middle concha, or it may divide and attach to some combination of these structures. (1) In our patient, the left uncinate process was divided along its entire length. The medial division was attached superiorly to the middle concha, and the lateral division was attached to both the fovea ethmoidalis and the lamina papyracea. Both portions of this bifid uncinate process attached to the inferior concha posteriorly. There was no mucosal continuity between the two divisions of this variant process. To our knowledge, this type of variation (bifid uncinate process) has not been defined in the literature, although there are some reports of patients who presented with a slit or ostium of the anterior surface of the uncinate process.

Our patient had a medial bend in the uncinate process of the right nasal cavity, and that is where the right-sided polyp originated. On the left, the polyp originated in the medial division of the bifid uncinate process. Neither polyp involved the osteomeatal complex. Only the left maxillary sinus ostium was occluded by polypoid mucosa. The right-sided polyp mimicked an antrochoanal polyp and extended posteriorly to the nasopharynx without involving the maxillary sinus.

Choanal polyps arising from the antrum, sphenoid sinus, septum, superior concha, and inferior concha have been reported previously. Our case is of particular interest because it illustrates an uncommon presentation of a choanal polyp--the one that originated in the right uncinate process. Choanal and antrochoanal polyps are often unilateral, and inverted papilloma should always be included in the differential diagnosis. (4) The literature also contains a few reports of bilateral antrochoanal polyps. (5,6) The polyps in our patient were not considered to be bilateral choanal polyps because the polyp on the left uncinate process did not extend to the nasopharynx while the one on the right did.

Treatment strategies for solitary nasal polyps should be based on eliminating mucosal contacts, as this will prevent recurrence. Both of our patient's polyps were removed via limited endoscopic sinus surgery (uncinatectomy only), which is an appropriate treatment for solitary uncinate polyps. More advanced endoscopic sinus surgery may be required when additional pathology is seen in the adjacent paranasal sinuses.

References

(1.) Stammberger H. Endoscopic and radiologic diagnosis. In: Stammberger H. Functional Endoscopic Sinus Surgery: The Messerklinger Technique. Philadelphia: B.C. Decker; 1991:145-271.

(2.) Pawankar R. Nasal polyposis: An update: Editorial review. Curr Opin Allergy Clin Immunol 2003;3:1-6.

(3.) Yanagisawa E, Joe JK. Polypoid change of the uncinate process. Ear Nose Throat J 2000;79:142-4.

(4.) Ku PK, Tong MC, Ho RW, van Hasselt A. Case report of a mass that mimicked an antrochoanal polyp. Ear Nose Throat J 1999;78: 556-7.

(5.) Sinha SN, Kumar A. Bilateral antrochoanal polyps. Ear Nose Throat J 1980;59:178-9.

(6.) Basu SK, Bandyopadhyay SN, Bora H. Bilateral antrochoanal polyps. J Laryngol Otol 2001; 115:561-2.

Can Alper Cagici, MD; Cem Ozer, MD; Ismail Yilmaz, MD; Filiz Aka Bolat, MD; Ozcan Cakmak, MD

From the ENT Department (Dr. Cagici, Dr. Ozer, Dr. Yilmaz, and Dr. Cakmak) and the Department of Pathology (Dr. Bolat), Baskent University Faculty of Medicine, Adana Teaching and Medical Research Center, Adana, Turkey.

Reprint requests: Dr. Can Alper Cagici, ENT Department, Baskent University Faculty of Medicine, Adana Teaching and Medical Research Center, Baraj Yolu 1. Durak, 01150 Seyhan, Adana, Turkey. Phone: [phone]; fax: [phone]; e-mail: [e-mail]