What Is Warthin's Tumor?
Warthin's tumor, also known as Cystadenolymphoma, is a benign and frequent salivary gland neoplasm that represents about 2 to 15 percent of all primary epithelial tumors of the parotid gland. It is a common tumor of the parotid gland with a double layer of epithelial cells resting on a dense lymphoid stroma. Other names of this tumor are,
- Papillary cystadenoma lymphomatosum papilliferum.
- Adenolymphoma.
It is the most common or rather the second most benign salivary gland tumor after pleomorphic adenoma.
What Are The Clinical Features of Warthin's Tumor?
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Appearance: People with Warthin's tumor are usually asymptomatic. In appearance, Warthin's tumors appear as round or ovoid nodular masses that are usually painless. They can either be fluctuant or firm on palpation. Warthin's tumor is a slow-growing multicentric tumor and can affect either one or both parotid glands. Almost 70% of bilateral salivary gland tumors are Warthin's tumors. Occasionally they can also occur within the oral cavity, larynx, or cervical lymph nodes.
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Prevalence: Usually, the prevalence is more in male smokers and in patients on radiation therapies, particularly after the fourth decade of life. But it is more prevalent in the sixth to seventh decade of life. Also, males are more predisposed than females.
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Microscopic Appearance: Warthin's tumor is histologically characterized by a dense lymphoid connective tissue or stroma and a double layer of oncocyte-filled epithelium with a papillary or a cystic architectural pattern.
In What Other Sites Can Warthin's Tumor Develop?
The incidence of Warthin's tumor outside the parotid gland boundaries or extra parotid space is very rare but is possible. In a few reported cases, there is evidence of Warthin's tumor occurring in the peri-parotid lymph node, nasopharynx, eyelid, and oral cavity. Also, it may, in some cases, occur simultaneously alongside pleomorphic adenoma and salivary duct carcinoma (as per dental literature, multiple cases of simultaneous histomorphologic pattern changes are observed alongside these lesions also).
Is Warthin's Tumor a Cancer?
Warthin's tumor is not a cancerous tumor. It is benign. But it can transform into cancer. Though it has an extremely rare or low chance of turning or evolving into a malignant lesion, a few cases with a malignant change of around 1% exist in long-standing or chronic cases. In such cases, they transform into the following malignant lesions:
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Lymphoma - It is a malignancy or cancer of the lymphatic system and can be of two types - non-Hodgkin’s and Hodgkin’s lymphoma.
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Merkel Cell Carcinoma - These are very rare forms of skin cancer that can be usually found on the neck, face, and head region.
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Adenocarcinoma - They are the cancerous tumor in the epithelial tissues that are formed from the glandular structures.
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Basal Cell Carcinoma - These are the skin cancer types that start in the basal cell.
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Mucoepidermoid carcinoma - It is the malignant and most common invasive salivary gland tumor.
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Oncocytic Carcinoma - It is a malignant epithelial tumor that arises from the monocytes.
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Salivary Duct Carcinoma - It is a salivary malignancy that can be mainly found in parotid and submandibular salivary glands.
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Squamous Cell Carcinoma - It is a skin cancer that occurs in the squamous cells of the outer and middle layers of the skin.
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Warthin's Adenocarcinoma - It is also a salivary gland tumor and a malignant form of Warthin’s tumor.
How Is Warthin's Tumor Diagnosed?
Diagnostic Criteria To Identify Warthin's Tumor:
1) Magnetic Resonance Imaging (MRI) - On MRI examination, Warthin's tumors are often seen as encapsulated lesions. The lesions are well-defined and can be bilateral too on an MRI scan. The signal characteristics usually are:
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T1 - It means it is a low to intermediate focal signal that is of high intensity and shows a cystic lesion with cholesterol components.
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T2- A signal intensity that is variating and shows the presence of heterogeneous lesions.
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T1 C+: The solid portions of the cyst are enhanced radiographically, while the cystic components do not take up the contrast.
For the diagnosis of Warthin's tumor, these lesions show low or intermediate T1-weighted signal features, whereas the neoplasm shows intermediate signal intensity on T2-weighted images. The solid portion is predominant in Warthin's tumors, and small cystic portions or components may be seen with thin uniform walls and without any contrast or enhancement. A well-defined contour is a crucial finding in distinguishing benign tumors from malignant or metastatic neoplasms. Magnetic resonance imaging will identify not only the capsule but also the cystic content of the mass with higher soft-tissue resolution.
2) CT (Computed Tomography) Scan Diagnosis - In a CT scan, Warthin's tumor appears as a well-defined solid cystic lesion of the superficial lobe of the parotid gland or of the parotid gland duct tail with intralesional attenuations signifying cystic changes. Mural nodules (composed of reactive or benign element cells) are usually clearly indicative of the diagnosis of this tumor on a CT scan.
3) Cytology - On cytologic examination, the smears characteristically show oncocytic epithelial cells without atypia and alongside infiltration by polymorphous lymphocytes and cellular debris. Mucinous differentiation and squamous cells with mixed inflammation are not usually observed in this benign lesion. If they are observed, then it indicates a lesion similar to the differential diagnosis.
4) Fine Needle Aspiration Cytology (FNAC) - Fine needle aspiration cytology is a beneficial diagnostic method for the preoperative assessment of Warthin's tumor. When there is a presence of both lymphocytes and oncocytes in the tissue fragments in the cystic contents of the tumor, then a positive diagnosis of Warthin's tumor can be made by the pathologist. Hence, FNAC remains a reliable method for diagnosis.
5) Immunoreactivity Test - The epithelial component as per immunohistochemistry is that the epithelium is immunoreactive for cytokeratin cocktail. The lymphoid portions also show kappa and lambda light-chain polyclonal variants.
What Other Tumors Are Similar To Warthin's Tumor?
Differential Diagnosis:
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Pleomorphic adenoma.
Other salivary gland tumors like,
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Mucoepidermoid carcinoma.
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Adenoid cystic carcinoma.
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Acinic cell carcinoma.
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BLEL (benign lymphoepithelial lesion).
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Infiltrative lesions.
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Parotid gland metastasis or malignancy of nodes.
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Parotid non-Hodgkin's lymphoma.
How Can Warthin's Tumor Be Treated?
Management By The Surgeon: An oral and maxillofacial surgeon or the dentist, after diagnosing the lesion as a parotid gland tumor, may cross-check the diagnosis by repeating FNAC (Fine needle aspiration cytology) in patients with anatomic or physiologic disorders or alterations as well as in comorbid patients to ensure an alternative option to surgery. This is because, in these patients with the above conditions or alterations, the risk of facial nerve paralysis may exist. However, in a majority of the cases with Warthin's tumor, the only mainline strategy is surgical management which is parotidectomy or surgical resection of the affected parotid gland with facial nerve preservation.
In clinical cases which do not warrant a full resection of the gland, capsular dissection is a reasonable alternative for some oral surgeons.
Either way, Warthin's tumor has a recurrence rate of less than 2 % after parotidectomy. Radiation therapy, immunotherapy, or chemotherapy is unnecessary in the management of this benign tumor. Some maxillofacial surgeons also believe that since the nature of the tumor is non-recurrent and without any malignant potential, enucleation remains an efficacious surgical alternative to preserve the facial nerve and to conservatively treat the tumor. Enucleation is also considered a safer option and with lesser postoperative complications, though with increased operating time.
Conclusion:
Warthin's tumor is a painless nodular lesion of the salivary gland with no malignant risk and with a negligible recurrence rate. However, it requires medical attention from the surgeon, timely diagnosis by proper criteria, and diagnostic tools that can prevent malignant potential as well as recurrence rate in 1-2% of the severely affected cases. Facial nerve preservation with conservative surgical treatment remains the focus of the management strategy in these cases.
