Pleomorphic adenoma of the soft palate: major tumor in a minor gland

Salivary gland tumors are a relatively rare and morphologically diverse group of lesions. Pleomorphic adenoma is a benign tumor of the salivary gland that consists of a combination of epithelial and mesenchymal elements. The tumor most commonly arises from the parotid (60-70%) or submandibular glands. It develops less frequently in a minor salivary gland, presenting as an intraoral mass depend on the soft palate. We describe a case of benign pleomorphic adenoma of soft palate in a 45 year old female with computed tomography and histopathological findings. This patient presented in ENT department with history of gradually increasing mass lesion in the palatal region over a period of few months.


Introduction
Pleomorphic adenoma is the most common tumor (60%) of major and minor salivary glands, nearly 70% of the tumors of minor salivary glands are Pleomorphic adenomas, and the most common intraoral site is the palate, followed by upper lip and buccal mucosa [1]. Studies have reported that in world population 13.9-51.4% of all salivary gland tumors arise from an intraoral site and 34.7-67.1% of them are benign [2]. This is a tumor of diverse histological and topographical presentation. The differential diagnoses are many and atypical presentations of this tumor are not uncommon. We report a case of a pleomorphic adenoma with predominant plasmacytoid myoepithelial cells arising in minor salivary glands of the soft palate in a 45 year old female.

Patient and observation
A 45 year-old unmarried female, presented in the department of otorhinolaryngology with chief compliant of slow growing swelling over palate since last 6 months. The lady also complained of pain over swelling while swallowing along with difficulty in deglutition because of swelling. There was no history of headache, vertigo, ear discharge, trauma or any other associated symptoms. There was no history of fever, weight loss, bleeding, pus discharge or any other type of discharge from the swelling. The personal history of the patient did not reveal any history of smoking, or any other addiction. On past history there was no history of similar illness in past neither there was any past history of significant medical or surgical illness. There was no family history of similar complaints.
The patient did not take any treatment for the above complaints

Discussion
Pleomorphic adenoma is the most common tumor of major salivary glands, although approximately 80% of these are found in parotid gland. About 4-5% of pleomorphic adenomas are seen in minor salivary glands, amongst which palate is one of the site [1]. Other sites include submandibular gland (8%), lips, buccal mucosa, gingiva and tongue. It is composed of epithelial and myoepithelial cells arranged with various morphological patterns, demarcated from surrounding tissues by a fibrous capsule [3]. It also ranks first as the most common tumor of the intraoral salivary glands of which palate is the most common intraoral site, followed by upper lip and Page number not for citation purposes 3 buccal mucosa. Muco-epidermoid carcinoma is the most common malignant salivary gland tumor, while pleomorphic adenoma is the most common benign counterpart. Pleomorphic adenoma of the palate is rare [3]. Patients with pleomorphic adenomas of the minor salivary glands present mostly in fourth to sixth decades, with a slight predominance in female [4]. They usually present as a unilateral, painless, slow-growing mass in the parotid gland.
However, when they originate in the hard and soft palate they present typically as a firm or rubbery submucosal mass without ulceration or surrounding inflammation. propensity for malignant transformation is documented to be 1.9-23.3% [7]. We performed complete excision of tumor with overlying mucosa and surgical wound was closed with advancement of adjacent mucosa. This produced an excellent result. The excised region can be left to heal by secondary intention also. In this case the tumor itself served as tissue expander, to advance adequate mucosal coverage, and achieve primary healing.

Conclusion
Pleomorphic adenoma, though a common entity, is still a challenging tumor for pathologist, radiologist, and the surgeon. Its diverse histological and topographical property makes the tumor special. The examining clinician and treating surgeon must be aware of its recurrence, longevity, and malignant potential if incorrectly diagnosed or treated.