INTRANASAL PLEOMORPHIC ADENOMA ARISING FROM THE LATERAL NASAL WALL

SUMMARY

Pleomorphic adenoma is very rare in the sinonasal region, with the most common localization on the nasal septum, followed by lateral nasal wall. In the case presented, a 72-year-old woman was complaining of the right sided nasal obstruction without any other symptoms. The symptom started a year before and increased progressively. Anterior rhinoscopy revealed a mucosa-covered, smooth-surfaced, soft, polypoid, pale, grayish-pink in color mass in the right nasal cavity, approximately 2x2 cm in size. Nasal endoscopy showed the mass to have a broad base on the lateral nasal wall. Computerized tomography scan showed a homogeneous, solid soft tissue mass, 25x18x12 mm in size, which was attached to the lateral nasal wall, behind the nasal vestibule, just in front of the inferior turbinate. Endonasal endoscopic complete tumor excision was performed, during which some spillage of the tumor occurred. Histology diagnosis was pleomorphic adenoma of minor salivary glands. The patient was followed up on regular basis and had no tumor recurrence in the 6^th postoperative year. Intranasal pleomorphic adenoma arising from the lateral nasal wall in front of the inferior turbinate is extremely rare, so the presented case is probably the first ever published.

Introduction

Pleomorphic adenoma (PA) is the most common neoplasm of salivary glands. It occurs mostly in major salivary glands. In minor salivary glands, it can occur anywhere within their distribution in the upper aerodigestive tract, where the incidence is 8%-10% of PA cases (1, 2).

Pleomorphic adenoma is rare in the sinonasal region. Rha et al. published a single institution case series combined with a comprehensive review of the literature (1). Their search of the literature over a 50-year period yielded only 93 published cases of sinonasal PA (+8 cases of carcinoma ex PA), and the authors described seven cases of their own. They also found that sinonasal PA involves patients in the fifth decade of life on average, with some female predominance (1). Patients usually presented within 1 year of the onset of symptoms, with the most frequent symptom being unilateral nasal obstruction, followed by epistaxis (1-4). Karligkiotis et al. published a case series of 5 patients, suggesting a total number of less than 120 cases (arising from the nasal septum, lateral nasal wall, and nasopharynx) published so far (4). In the sinonasal region, the most common localization of PA is nasal septum, followed by lateral nasal wall, usually the inferior turbinate (1-4).

Intranasal PA is a painless, slow-growing mass, so computerized tomography (CT) will show nonspecific benign features (5). Usually, it is a well-defined soft-tissue mass, which can show adjacent bony displacement and expanding erosion. Magnetic resonance imaging (MRI) will show iso- to hyperintensity on T2-weighted images (WI) and hypointensity on T1-WI (5).

Complete surgical excision of the tumor is the treatment of choice for intranasal PA, which can be achieved with endonasal endoscopic surgical approach in most cases (1, 2). Approximately only 50 endoscopically treated cases have been reported in the literature so far^4.

On histology, intranasal, like any other PA, is a mixed (two-component) tumor. There is a cellular component comprising epithelial and myoepithelial cells, and mesenchymatous stroma (myxoid, hyaline, chondroid, and osteoid) (5). Intranasal PAs have a more dominant epithelial component (vs. stromal components) than is seen in the major salivary gland PAs (3, 5).

Case Report

A 72-year-old woman was referred to our Department of Otorhinolaryngology and Head and Neck Surgery for evaluation of unilateral nasal obstruction. She was complaining only of the right sided nasal obstruction without any other symptoms. The symptom started a year before and increased progressively.

Anterior rhinoscopy revealed a mucosa-covered mass in the right nasal cavity, approximately 2x2 cm in size. The mass was smooth-surfaced, soft, polypoid, pale, grayish-pink in color. Nasal endoscopy showed the mass to have a broad base on the lateral nasal wall (Fig. 1). CT scan showed a homogeneous, solid soft tissue mass, 25x18x12 mm in size, which was attached to the lateral nasal wall, behind the nasal vestibule, just in front of the inferior turbinate, with no intratumoral calcifications (Fig. 2). The mass pushed against the surrounding structures without invading them. The radiologist’s diagnosis was a slow growing benign lesion.

Fig. 1.

Nasal endoscopy of the intranasal pleomorphic adenoma.

Fig. 2.

Axial computed tomography scan of the intranasal pleomorphic adenoma (tumor marked with arrow).

Endonasal endoscopic complete tumor excision was performed under general anesthesia, during which some spillage of the tumor occurred. Macroscopically, it was a well-circumscribed, round, soft tumor, mostly gelatinous with homogeneous whitish-yellowish content and thin capsule (Fig. 3). The histopathologist made a definitive diagnosis of pleomorphic adenoma of minor salivary glands (Fig. 4).

Fig. 3.

Macroscopic view of the intranasal pleomorphic adenoma (tumor content marked with arrow).

Fig. 4.

Tumor histology: pleomorphic adenoma, a mixture of ductal epithelial cells, basal and myoepithelial cells, and variable amounts of stroma, both hyaline and chondromyxoid (hematoxylin-eosin, X100).

The patient was discharged from the hospital one day after surgery without any complications. The patient was followed up on regular basis and had no tumor recurrence at 5.5-year postoperative follow up (she was operated on in December 2016) (Fig. 5).

Fig. 5.

Nasal endoscopy: postoperative follow up at 5.5 years (no tumor recurrence).

Discussion

Pleomorphic adenoma of the minor salivary glands can be found in the oral cavity (hard palate, soft palate, superior lip), ear, external nose and nasal cavity, paranasal sinuses, nasopharynx, lower eyelid, larynx, trachea, pterygopalatine fossa, etc. (1, 2). However, they are extremely rare in the nasal cavity (1, 4).

The mean age of patients with intranasal PA is 45.4 years (1); however, our patient was much older, 72 years of age. The most frequent symptom in these patients at presentation is unilateral nasal obstruction, as in our case, but they can also present with epistaxis, nasal mass, cheek or nasal swelling, external deformity, mucopurulent rhinorrhea, and epiphora (1-4).

Intranasal PAs are most often localized on the nasal septum, and according to Rha, it is found in 57.4% of all patients (1-3). The lateral nasal wall is a possible localization, usually on the inferior turbinate (1, 2). In the literature available on PubMed database, we found no case of intranasal PA localized on the lateral nasal wall in front of the inferior turbinate, as in the case presented.

The natural history of intranasal PA is slow growth with conformity of the adjacent anatomy, as also seen on our patient’s CT scan (1, 3, 6). Endonasal endoscopic complete resection of the tumor was done. The reported case is typical considering its size (25x18x12 mm) and broad base. The mean size of intranasal PA is usually 3.6 cm (range 0.5-10 cm) and most of them have a broad base (1, 3). Cross-sectionally, they are well-circumscribed, round or lobular nodular tumors surrounded by a fibrous capsule of varying thickness, firm consistency, or in some cases, as in ours, are soft and myxoid (gelatinous) (1, 5).

In postoperative follow up, the main problems with PA are the possibility of recurrence, malignant transformation, and metastasizing. The reported recurrence rate of intranasal PA (≤10%) is lower than that recorded in parotid PA (1, 3).

During surgery, we had some tumor spillage. Tumor disruption and spillage have been reported as variables with an independent effect on parotid PA recurrence of punctured tumors (26.9%). Recurrence has been reported in 80% of cases with spillage (6). Despite these data, our patient is still without recurrence after 5.5 years of follow up.

Malignant transformation of PA has been reported, meaning carcinoma ex PA and malignant mixed tumor (1, 2, 4). The diagnosis of benign metastasizing PA of the salivary gland is extremely rare and still under debate (1, 4).

Postoperative long-term follow up is necessary in all patients (1, 2), so we will continue to follow up our patient.

Conclusion

Intranasal PA arising from the lateral nasal wall in front of the inferior turbinate is extremely rare, so the case presented may be the first ever published. Complete surgical excision is the treatment of choice, if possible, by means of endoscopic endonasal surgery, paying special attention not to cause tumor spillage and puncture. The patients need long-term postoperative follow up.