From the Guidelines
Pleomorphic carcinoma originates from the epithelial lining of various organs, with the most common site being the salivary glands, particularly the parotid gland, followed by the submandibular and sublingual glands. The cancer arises from the epithelial cells that undergo malignant transformation with significant cellular and nuclear pleomorphism (variation in size and shape) 1. This rare and aggressive cancer typically contains a mixture of epithelial and mesenchymal components, suggesting that the tumor cells undergo epithelial-mesenchymal transition during development.
Key Points
- The risk of malignancy is inversely proportional to the size of the gland, with the sublingual gland having a higher risk of cancer compared to the parotid gland 1.
- The majority of salivary gland tumors are benign, with pleomorphic adenoma being the most common benign tumor, while a smaller percentage are malignant tumors, including mucoepidermoid carcinoma, adenoid cystic carcinoma, lymphoma, and acinic cell carcinoma 1.
- Patients with pleomorphic carcinoma typically present with a palpable abnormality or pain, and may experience weakness of the facial muscles if there is perineural spread of disease 1.
- The pleomorphic appearance results from genetic instability and mutations that lead to dedifferentiation of the cells, causing them to lose their specialized characteristics and adopt a more primitive, disorganized growth pattern 1.
Diagnosis and Treatment
- MRI orbits, face, and neck without and with IV contrast is recommended for staging and post-therapy assessment of head and neck cancer, including pleomorphic carcinoma, due to its superior soft tissue contrast resolution and ability to delineate the soft tissue extent of the tumor 1.
- Surgical excision is the primary treatment for pleomorphic carcinoma, with the goal of complete excision and minimizing the risk to the facial nerve 1.
From the Research
Origin of Pleomorphic Carcinoma
- Pleomorphic carcinoma, also known as carcinoma ex pleomorphic adenoma, is a rare malignancy that originates from the salivary glands 2, 3.
- The majority of cases arise in the major salivary glands, with the parotid gland being the most common site, followed by the submandibular gland 2, 3.
- Pleomorphic adenoma, a benign tumor, is the most common neoplasm of the major salivary glands and can undergo malignant transformation, resulting in carcinoma ex pleomorphic adenoma 2, 4.
- The minor salivary glands can also be affected, with the palate being a rare site for pleomorphic adenoma and carcinoma ex pleomorphic adenoma 3, 5.
- The malignant component of the tumor can vary, including salivary duct carcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, squamous cell carcinoma, or adenocarcinoma, not otherwise specified 3.
Sites of Origin
- Parotid gland: the most common site for pleomorphic adenoma and carcinoma ex pleomorphic adenoma 2, 3, 4, 6.
- Submandibular gland: the second most common site for pleomorphic adenoma and carcinoma ex pleomorphic adenoma 2, 3, 4, 6.
- Minor salivary glands: including the palate, lip, nasal cavity, pharynx, larynx, and trachea 3, 5, 4.
- Other sites: pleomorphic adenoma and carcinoma ex pleomorphic adenoma can also occur in other rare sites, such as the upper lip 5.