Pleomorphic adenoma (PA) is the most common tumor of the salivary gland and is characterized by cytomorphological and architectural diversity [1]. Patients usually present with a painless, mobile mass with no other associated symptoms. Standard radiological examinations in surgical dentistry are generally of no value. Recurrences and malignant transformation are rare and the prognosis is usually excellent. We report a case of pleomorphic adenoma located in the vestibule of the upper anterior sector, more precisely the alveolar mucosa

A 24-year-old young woman, with no particular medical history, consulted t the department of oral surgery and pathology of Ibnou Rochd’s hospital of Casablanca, in June 2020 regarding a painless discomfort in the upper anterior buccal mucosa. That had been progressing over a year ago. Upon exo-oral examination, facial symmetry is conserved. No lymphadenopathy was revealed on palpation of the lymph node areas. During the intraoral examination, a nodular formation was reported, lined with a healthy mucosa, and located on the mucco-gingival line and facing the upper left canine. On palpation, this nodule is asymptomatic, firm and mobile in relation to the underlying plane (Figure1). The radiological examination did not reveal any particularities. (Figure 2). Intraoral surgical removal of the tumor was performed under local anesthesia. The intervention consisted of a simple superficial incision of the mucosa, allowing the exteriorization of a gelatinous nodule (Figure 3). Two stitches were made. Histological analysis specifies that it is a well-defined nodular lesion, measuring 1.5x 1 cm corresponding to a nodular center, surrounded by fibrosis (Figure 4). The lesion is a mixed proliferation of monomorphic epithelia without atypias or mitosis and a mesenchymal tissue with myxochondroid and fibro-collagen foci. The histological analysis confirmed the diagnosis of a pleomorphic adenoma excised in toto.

Figure 1: Intraoral examination: a nodular formation lined with a healthy mucosa,  located on the mucco-gingival line and facing the upper left canine.

Figure 2: The radiological examination did not reveal any particularities.

Figure 3: A simple superficial incision of the mucosa, allowing the exteriorization of a gelatinous nodule.

Figure 4: well-defined nodular lesion, measuring 1.5x 1 cm.

Pleomorphic adenoma (PA) is one of the most common benign tumors of the salivary glands [1]. It’s also called mixed tumor because of its dual composition, epithelial and mesenchymal [2,3]. In general, they affect the main salivary glands with a major predilection for the parotid glands (75%), and occurs rarely in the minor salivary glands. They are distributed between the submandibular gland (10%) and the accessory salivary glands (5 to 10% of cases) (4,5). For our patient, the tumor was intra-oral developing on the upper buccal mucosa. Other rarer locations have been reported in the literature such as the nasal septum, nasal vestibule, tuberosity and base of the tongue [4,6].  PA occurs in people of all ages, however, it is more common in the third to sixth decade of life, with a female predominance (Ratio 2: 1) [7]. Regardless of its location, the pleomorphic adenoma usually progresses in a slow and asymptomatic manner.  The intraoral is described in the literature usually as submucosal swelling that is small, painless, bumpy and lined with a normal and non inflammatory mucosa [6]. This was the case with our patient. Macroscopically the tumor is nodular, well circumscribed. Its consistency is variable, firm, soft, or sometimes gelatiniform the same as was described in our case [6]. Histologically, pleomorphic adenoma is characterized by a cellular polymorphism with the presence of myoepithelial, epithelial and stromal cells, hence the name mixed tumor [3]. In the oral cavity, this tumor has the particularity of not being encapsulated [4,6]. Its pleomorphic nature is in reference to a great architectural richness as opposed to the monomorphism of the epithelial and myoepithelial cells, of which the tumor is composed. PA may exhibit significant variability in its architecture, cell types, and structure of the stroma. The latter often being myxochondroid [8]. The treatment is mainly surgical. Large and complete excision is the treatment of choice to prevent recurrence [4].  On a clinical level, the differential diagnosis is brought with all benign tumors of the oral mucosa having a nodular or gelatiniform appearance. Its prognosis is generally good, but remains marked by a high risk of recurrence after surgery, and the possibility of a carcinomatous transformation, which requires a regular monitoring [6]. 

The diagnosis of pleomorphic adenoma is based on a complete and thorough history, clinical examination and histopathology analysis. Excision with safety margins must always be performed to avoid recurrence similarly as the presented case.

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