Pleomorphic adenoma of the soft palate

Pleomorphic Adenoma of the Soft Palate

Authors: Kishore C Shetty*, Vadisha Bhat**, Shubha P Bhat***

*Professor of ENT, **Associate Professor of ENT, ***Assistant Professor of Pathology

Institution: K S Hegde Medical Academy, Deralakatte, Mangalore- 575018, Karnataka, India

Corresponding Author:

Dr Vadisha Bhat

Associate Professor of ENT

K S Hegde Medical Academy

Deralakatte, Mangalore 575018

Karnataka, India

Email: [email protected]

Abstract:

The majority of minor salivary gland tumors are malignant. Pleomorphic adenoma is a benign

neoplasm which is commonly encountered in parotid and other major salivary glands.

Occasionally, they may develop in minor salivary glands of the palate. We report a case of

pleomorphic adenoma of minor salivary glands in the soft palate.

Introduction:

Salivary gland tumors account for less than 3% of the head and neck tumors.1 Mixed tumor of

the salivary gland, or pleomorphic adenoma, is a benign tumor arising mainly in the major

salivary glands (65%), especially in the parotid and, less frequently, in accessory salivary glands

(35%).2 A small minority (8%) are located in the oral cavity, neck and nasal cavity.

3 The most

common site for minor salivary gland pleomorphic adenoma is the palate, though it can also

occur in the upper lip, cheek, floor of the mouth, larynx and trachea.4 Intraoral pleomorphic

adenoma appears as a slowly growing, painless mass, usually in the fourth or fifth decade.5 It

has its highest incidence between 30 to 60 years of age with female predominance.6 Fine-needle

aspiration cytology (FNAC) and incisional biopsy can aid as diagnostic tools.1,7,8

Surgical

resection is the treatment of choice.6 Pleomorphic adenoma generally does not recur after

adequate surgical excision.8 The potential risk of malignant transformation of the pleomorphic

adenoma is about 6%. The risk is increased by delay in diagnosis.2 We report a case of

pleomorphic adenoma of the soft palate in an elderly lady, which was treated surgically.

Case Report:

A female of 65 years presented with a slow-growing swelling

on the soft palate. The swelling was noticed when she started having a foreign body sensation in

the oral cavity. The swelling was painless and she did not complain of dysphagia or difficulty in

breathing. On examination, there was a swelling measuring 4 cm by 3 cm on the soft palate to

the left of midline. The mass was reaching up to the upper pole of the left tonsil. The lateral

margin of the mass could not be demarcated. On palpation, the swelling was firm in consistency,

with a small stony hard area, within. The mucosa overlying the swelling was intact, but was

stretched and shiny compared to the other area (Figure 1 to the right). There were no enlarged

cervical lymph nodes. A clinical diagnosis of minor salivary gland neoplasm was made. Fine

needle aspiration cytology of the mass showed features suggestive of Pleomorphic adenoma. CT

scan of the neck was done with contrast, which showed a well-defined, mildly-enhancing mass

measuring about 4 cm by 3 cm on the right soft palate with areas of calcification. Laterally, the

mass was impinging on the medial pterygoid muscle but without loss of plane. Inferiorly the

lesion extended up to the upper pole of the tonsil resulting in the inferior displacement of the

tonsil. The major vessels were normal. (Figures 2,3,4)

Figure 2: Axial CT Scan Figure 3: Axial CT Scan

Lower Level Figure 4: Coronal CT Scan

Excision of the mass was done under general anesthesia, with the patient in Rose’s position. The mass was excised with preservation of the overlying mucosa. Incision was closed in two layers

with absorbable sutures (Figures 6,7,8).

Figure 5: Sagittal

Reconstruction

CT Scan

Figure 6: Tumor Being

Exposed After Elevation of

Mucosa

Figure 7: Wound Sutured After

Excision of Tumor

Left Picture: Wound Sutured After Excision of Tumor

Right Picture: The mass was irregular in shape measuring 4.5 cm by 3 cm, firm in consistency

with some stoney hard areas (Figure 8 to the right). Cut surface showed pale/white solid areas,

cystic and myxoid areas.

The mass was sent for histopathological examination, which confirmed the diagnosis of

pleomorphic adenoma (Figure 9, 10). There was no evidence of malignancy.

Figure 9: Histopathology: Pleomorphic

Adenoma

Figure 10: Histopathology: Pleomorphic

Adenoma

High Magnification

The postoperative period was uneventful and the patient was allowed to take clear liquids after 4

hours, liquid and semisolids on the next day. She started taking regular food after 2 days and

was discharged on the third day. She is under regular follow up and there is no evidence of

recurrence or any other lesion in a 5 month follow-up period.

Discussion:

Neoplasms of the minor salivary glands are rare and represent 9%-23% of glandular tumors.9

The majority (40%-50%) of them are malignant,7 with only 18% being benign. Pleomorphic

adenoma is the commonest benign minor salivary gland tumor. It is commonly found in females

than in males, with a male/female ratio varying from 1:1.4 to 1:1.76. The palate being the most

common site, followed by lip, buccal mucosa, floor of mouth, tongue, tonsil, pharynx, retromolar

area and nasal cavity.10

It presents as a painless slow-growing mass.6 Our patient was a 65-year-

old female who presented with a slow-growing, painless swelling on the soft palate for one-year

duration. Differential diagnoses for this case include: Odontogenic and nonodontogenic cysts,

soft-tissue tumors, lymphomas and salivary gland tumors.8 The diagnosis of pleomorphic

adenoma is established on the basis of history, physical examination, cytology and

histopathology. CT scan and MRI can provide information of the location, size and extension of

tumor to surrounding superficial and deep structures.5

Fine-needle aspiration cytology and

incisional biopsy can aid in the diagnosis. The treatment of choice for pleomorphic adenoma in

the minor salivary gland is wide local excision with the removal of periosteum or bone if they

are involved.8

Our patient underwent excision of the mass in total with preservation of the

overlying mucosa. Microscopically, the intraoral pleomorphic adenoma lacks a well-defined

fibrous capsule. The tumor tissue is composed of epithelial and a mesenchymal component. The

epithelial component consists of tumor cells arranged in ducts, cords and sheets. Ducts are lined

by inner cuboidal and outer spindle-shaped myoepithelial cells. The mesenchymal area is

present in the hypocellular area and is composed of stellate and spindle-shaped myoepithelial

cells dispersed in a chondromyxoid matrix.2,5

Immunohistochemical stains prove positive for various cytokeratins, S100 protein, glial fibrillary

acid protein, vimentin, and smooth muscle actin. This describes the “mixed” nature of the tumor, both, stromal and epithelial lined.

2

Recurrences are not frequent. Simple enucleation of this tumor is believed to lead to a high local

recurrence rate and should be avoided. Rupture of the capsule, or tumor spillage, is also believed

to increase the risk of recurrence, so meticulous dissection is necessary.8 Rare cases of a

metastatic nature and malignant transformation have been reported.4

Conclusion:

The majority of minor salivary gland tumors of the soft palate are malignant in nature.

Nonulcerated, firm, dome shaped, nontender palatal masses of long duration should raise a high

index of suspicion for pleomorphic adenoma. CT scan with contrast and Fine Needle Aspiration

Cytology will aid in diagnosis. Complete extramucosal excision of the mass by a transoral route

provides cure.

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