Pleomorphic adenoma is the most frequent benign tumor of the salivary gland. It is a slow-growing tumor and is characterized by varying amount of myxochondroid stroma, produced by the myoepithelial cells. About 90% of benign neoplasm of major salivary glands is associated with the parotid gland. The occurrence of submandibular gland pleomorphic adenoma is uncommon. Pleomorphic adenoma have low proliferative rate and have a good prognosis. Presented here is the case of a 35-year-old lady with a swelling below the right angle of the mandible.
Keywords: Pleomorphic adenoma, salivary gland neoplasm, sub-mandibular gland
Salivary gland tumors are rare and account for nearly 3% of head and neck tumors. About 90% of benign neoplasm of major salivary glands is associated with the parotid gland. Pleomorphic adenoma is the most common benign tumor of the salivary gland.1 Pleomorphic adenoma is characterized by varying amount of myxochondroid stroma that is produced by the myoepithelial cells. Microscopic findings of necrosis, nuclear atypia, hyalinization, invasion of adjacent tissue and heightened abnormal mitotic activity are linked with an aggressive behavior or malignant transformation of pleomorphic adenoma. At times, histopathological confusion could occur due to extensive squamous differentiation, usually seen on fine-needle aspiration cytology (FNAC). Thus, at times, it could be misdiagnosed. Capsule infiltration, though not associated with malignant transformation, might play a role in pleomorphic adenoma recurrence.2 Pleomorphic adenoma have low proliferative rate and have a good prognosis.3
A 35-year-old lady presented to the outpatient department (OPD) with a swelling below the right angle of the mandible (Fig. 1 a and b).
Figure 1 a and b. Swelling below the right angle of the mandible.
The swelling was present since 2-3 years which was slowly growing in size. The swelling was nontender and mobile and measured 5 × 6 cm. There was no rise in temperature.
Patient was then planned for surgery after getting the basic preoperative investigations done which were: Hemoglobin (Hb) - 12.4 g/dL, total leukocyte count (TC) - 9,800 cells/mm3, differential count (DC) - N55L38E6M1, erythrocyte sedimentation rate (ESR) - 18 mm/hr, bleeding time (BT) - 2 minutes 15 seconds, clotting time (CT) - 3 minutes 35 seconds, blood group - B-ve, ICTC - negative, random blood sugar (RBS) - 104.5 mg/dL, urine - within normal limit. The surgery was done under general anesthesia (Fig. 2).
Figure 2. Intraoperative image.
The gland was excised in toto (Fig. 3), hemostasis was checked for and achieved. The patient tolerated the procedure well.
Figure 3. Excised gland.
The excised gland was sent for histopathological examination (Fig. 4). The microscopic picture coincided with the diagnosis of pleomorphic adenoma (Fig. 5). The microscopic picture showed proliferation of both epithelial and stromal elements.
Figure 4. Cut section of the gland.
Figure 5. Microscopic picture pointed to diagnosis of pleomorphic adenoma.
The epithelial proliferation is in the form of acini, tubercles, trabeculae. The stromal component is of chondromyxoid; at places stroma were seen having cartilaginous tissue.
Patient was put on broad-spectrum antibiotic postoperatively for a week and discharged on the 5th postoperative day. On the 10th postoperative day, the patient was called for follow-up and subcuticular suture removal; wound was healthy (Fig. 6).
Figure 6. Healthy wound on 10th day postoperatively.
Cases of submandibular gland pleomorphic adenoma are uncommon, though parotid gland cases are often encountered.1 Pleomorphic adenoma is the commonest benign tumor of the salivary glands4 and accounts for 90% of all salivary gland tumors.1
The submandibular gland represents the second most common site of pleomorphic adenoma after the parotid gland.1
Pleomorphic adenoma, an epithelial tumor of complex morphology, has epithelial and myoepithelial elements intermingled with mucoid, myxoid or chondroid tissue arranged in varied patterns and embedded in a mucopolysaccharide stroma.1
The differential diagnosis includes basal cell adenoma, adenocarcinoma, mucoepidermoid carcinoma and lymphoma.
Investigations like magnetic resonance imaging (MRI) and computed tomography (CT) are gold standard, while adjunctive procedures such as ultrasound-guided needle aspiration and FNAC may not assist with confirmation of diagnosis.
A direct submandibular incision is generally recommended, which gives easy access. The excision should be always in toto. Incomplete removal would result in recurrence. At times, the benign pleomorphic adenoma could transform into a malignant one (carcinoma ex-pleomorphic adenoma), with 25% of untreated pleomorphic adenomas estimated to undergo malignant transformation;5 hence, early definitive treatment is needed.
Pleomorphic adenoma is the most common benign neoplasm of the salivary gland and more commonly seen in parotid gland. It is uncommonly seen in sub-mandibular gland. Surgical excision in toto is the treatment of choice. If left untreated, it could cause recurrence and long-standing pleomorphic adenoma could become malignant.
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- Alves FA, Perez DE, Almeida OP, Lopes MA, Kowalski LP. Pleomorphic adenoma of the submandibular gland: clinicopathological and immunohistochemical features of 60 cases in Brazil. Arch Otolaryngol Head Neck Surg.2002;128(12):1400-3.
- Kazanceva A, Groma V, Smane L, Kornevs E, Teibe U. Proliferative potential in benign mixed salivary gland tumors and its value in primary and recurrent neoplasms. Stomatologija. 2011;13(2):35-41.
- Spiro RH. Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg. 1986;8(3):177-84.
- Bagga M, Bhatnagar D, Bhatnagar D. An unusual presentation of pleomorphic adenoma: A case report. J Indian Acad Oral Med Radiol. 2016;28:191-4.