Pleomorphic adenoma of the nasal cavity

Pleomorphic adenomas represent 80% of the salivary gland’s benign tumors. They are most often found in the parotid gland or in the submandibular gland. Pleomorphic adenomas of the nasal cavity are rare, with less than fifty cases reported to date. There are no treatment or follow up guidelines. The purpose of this article is to review the cases already described in the literature and to share our clinical experience. We describe the case of a 38-year-old woman with a history of a slow growing intranasal tumor with recurrent epistaxis, obstruction, and aesthetic deformation. The pre-operative assessment suggested a benign tumor, but the biopsies were inconclusive. The decision was taken to perform an open rhinoplasty to have an en bloc resection with margins control. The diagnosis of pleomorphic adenoma was established on the excised tumor. There were no post-operative complications. The early follow-up showed no signs of recurrence. We decided to closely follow the patient with frequent clinical examinations and yearly enhanced-MRIs for at least five years due to the recurrence and malignant transformation risks.


Introduction
Salivary gland tumors are rare, they represent around 3 % of all neoplasms. They are mainly located within the major salivary glands. Pleomorphic adenomas (PAs) represent 80% of benign tumors and are mostly found in the parotid gland or in the submandibular gland. Only 8 to 10 % of PAs grow in the minor salivary glands [1,2].
PAs are benign tumors which are at a risk of transforming into malignant tumors, mostly into carcinoma ex pleomorphic adenoma [3]. In the literature [1,4], this risk is estimated between 0% and 6% and increases further when the diagnosis of the tumor is delayed. If there is a malignant change, the prognosis gets worse, with a 5 years survival rate ranging between 30 to 50% [2].
Only a few case reports and case series have described PAs of the sinusonasal tract. There are no clear guidelines today regarding their diagnosis, treatment and follow up.
Having managed of a case of a woman with a pleomorphic adenoma of the nasal cavity, we therefore aim to describe its clinicopathological characteristics and treatment outcomes and to review the literature.

Case report
We are presenting the case of a 38-year-old woman (who has given her consent about the present report) with a history of multiple sclerosis. She had developed over 2 years a mass in the right nasal cavity causing an obstruction, recurrent bleeding and deformation of the nasal pyramid. There were no pain symptoms.
The clinical examination showed no abnormalities of the skin but the anterior rhinoscopy revealed a round mass on the lateral wall of the nasal cavity with a normal aspect of the mucosa. Biopsies under local anesthesia were performed but were inconclusive, showing inflammatory tissues and mycelial filaments. The CT-scan ( Figure 1) without contrast injection showed a nodular formation with well-defined limits, measuring 22mm x 15mm in the right nasal cavity. There was a doubt on a slightly lytic nature on the septum. The density was tissular, heterogenous, without necrosis and with slightly calcified borders. There were no lymphadenopathies.

Discussion
Heterotopic salivary glands are abnormally located; they are different from the accessory salivary glands which are a detached part of a major salivary gland that develops along the external ductal systems. They might originate from ectopic embryonic epithelial cells derived from ectoderm or from remanent vomero-nasal organs [5]. The heterotopic salivary glands are rarely the site of diseases [11].
The clinical presentation of our patient was quite similar to the other cases of intra-nasal PAs described in literature ( Table 1). PAs of minor salivary glands affect mainly women with a mean age of around 40 years old [5,7]. The most frequent symptoms are nasal obstruction and recurrent epistaxis [2], the aesthetic deformation of the nose is found in long evolving cases. The diagnosis is often delayed with symptoms evolving for over a year before diagnosis [5]. PAs of the nasal cavity mainly originate from the septum, although most of the mucosal glands of the nasal cavity are located on the lateral wall [6]. Cases have been reported in the nasal cavity, paranasal sinuses, nasopharynx, oropharynx, hypopharynx and the larynx.
In the upper respiratory tract, the most favorable site is the nasal cavity, followed by the maxillary sinus and the nasopharynx.
The differential diagnosis of intra-nasal PAs are: inverting papilloma, nasal polyp, malignant tumor such as carcinoma ex pleomorphic adenoma, unclassified mixed tumors, pyogenic granuloma, chondroma, and adenoid cystic carcinoma [5,12]. Despite the variety of tumors, the role of preoperative biopsy is discussed. In our case the biopsy was performed under local anesthesia without endoscopic guidance which might have produced too many superficial fragments. In their review, Rha et al found the biopsy and the final anatomopathological diagnosis to be different in 6 out of 14 preoperative biopsies [1].
Multiple surgical techniques are described. The main goal of the PA surgery is to remove the tumor completely, if possible en bloc. This can be achieved endoscopically or through an open surgery such as lateral rhinotomy, midfacial degloving or transpalatal surgery [1]. There is no gold standard surgical technique today. Karakus et al. argues that an endoscopic approach might produce less morbidity, reduce blood loss during surgery, decrease hospital stay, avoid external scars and excessive unnecessary resection, and enable the surgeon to better visualize the margins of the tumor [13].
The recurrence rate of intranasal PAs is reported to be of 8% with a mean follow up of 29 months. The known risk factors of recurrence are: the paranasal sinus location and a carcinoma ex pleomorphic adenoma component [1]. For PAs located in the parotid, the recurrence rate ranges from 2% to 5%, it occurs when the removal is subtotal. Zbären et al showed that stroma-rich tumors (myxoid PAs) are more likely to have an incomplete capsule and satellite tumors, making their recurrence potential higher [14].
There are no guidelines for intranasal PA follow up. Conventional surveillance regimens in PAs include a detailed history and clinical examination every 1-3 months for the first year after completion of treatment, every 2-6 months in the second year, and every 4-8 months for years 3 to 5. Five years after the completion of the treatment and if there is no evidence of recurrence, the patient may go on life-long yearly follow-ups. The role of imaging in the follow-ups is debated and is not compulsory. It is admitted that the first post-operative imaging should be made at least 6 months after treatment. After that, it is up to the clinician to individually adapt the frequency of enhanced MRIs [15,16]. We decided to perform an annual MRI for the first five years as the patient is at high risk of recurrence [17].

Conclusion
PAs must be kept in mind as a potential diagnosis for intranasal tumor with slow evolution and persistent symptoms. A biopsy alone does not allow to make a reliable diagnosis. The treatment of these tumors is surgical. There are no guidelines on the follow-ups, and in our experience and according to literature, the follow-up must be done clinically and with repeated MRI controls due to the recurrence and malignant transformation risks.

Compliance with Ethical Standards
There are no conflicts of interest for the authors in this study. The patient gave an informed consent.