Pathology of Pleomorphic Adenomas

Study Notes

Pathology of Salivary Neoplasms

Salivary neoplasms constitute 1.2% of all neoplasms and 5% of head and neck tumors.
The majority of these neoplasms are benign and most commonly arise in the parotid gland.

Pleomorphic Adenoma (Mixed Salivary Tumor)

The commonest tumor of salivary glands, representing 75% of parotid and 50% of submandibular gland neoplasms.
Distribution is equal between males and females, occurring in the fourth decade of life.
Characterized by slow rate of growth, perineural spread, and incomplete removal, leading to a high recurrence rate.

Warthin's Tumor (Adenolymphoma)

Usually found in the lower part of the parotid gland, representing 15% of all parotid tumors and bilateral in 10-15% of cases.
Thought to arise from heterotopic salivary tissue in the parotid lymph nodes.
Macroscopically, multiple cysts of variable sizes are seen.
Microscopically, the tumor is formed of epithelial-lined spaces filled with creamy material, surrounded by lymphoid tissue.
Tends to affect elderly people and is related to smoking.

Pathology of Carcinoma of Salivary Glands

Occurs in elderly age, more common in females, and may start de-novo or on top of a mixed salivary tumor.
Types of carcinoma:
- Mucoepidermoid carcinoma: arises from the duct epithelium, the commonest member of the group, affecting the parotid.
- Adenoid cystic carcinoma (cylindroma): the commonest malignancy affecting the minor salivary glands.
- Acinic cell carcinoma
- Adenocarcinoma
- Carcinoma ex pleomorphic adenoma
- Epidermoid carcinoma (squamous cell carcinoma)
- Lymphoma

Clinical Picture of Benign Salivary Neoplasm

Symptoms: painless, slowly growing swelling in the parotid region.
Signs:
- Inspection shows a swelling over the angle of the mandible, elevating the lobule of the ear.
- The swelling is superficial to the masseter muscle, and the facial nerve is not affected.
On palpation:
- The swelling is not hot, not tender, not attached to the skin, masseter, or mandible.
- The swelling is well-defined, with varying consistency from firm to cystic.

Clinical Picture of Carcinoma of the Parotid

The patient commonly complains of a steadily enlarging swelling on the side of the face.

Description

This quiz covers the characteristics of pleomorphic adenomas, including their epithelial, myoepithelial and stromal components, and their tendency to recur after enucleation. Learn about their slow growth and potential for malignant transformation.