Warthin tumor (papillary cystadenoma lymphomatosum) is the second most common benign tumor of the parotid gland, accounting for 5-15% of all parotid neoplasms. It almost always arises in the posterior-inferior tail of the parotid gland; this location is due to the embryological concentration of lymphoid tissue in this area. Bilateral involvement occurs in 10-20% and multifocality in 12-20% — this feature distinguishes it from other salivary gland tumors. Histologically, it contains double-layered oncocytic epithelium with lymphoid stroma; oncocytic cells harbor abundant mitochondria. It is significantly more common in males (M:F = 5:1) and has a strong association with smoking. Typical age range is 50-70. Malignant transformation is extremely rare (<1%). Clinically, it presents as a slowly growing, painless, palpable mass; sometimes complicated by inflammatory episodes characterized by recurrent swelling.
Age Range
50-80
Peak Age
65
Gender
Male predominant
Prevalence
Common
The characteristic imaging findings of Warthin tumor arise from the unique histological composition of the tumor. The double-layered oncocytic epithelium and underlying lymphoid stroma create two distinct tissue components. The dense mitochondrial content of oncocytic cells provides an active uptake mechanism for Tc-99m pertechnetate (NIS expression) and these cells also actively metabolize FDG. The lymphoid stroma and proteinaceous/hemorrhagic cystic fluid produce intermediate-to-low signal on T2-weighted MRI — this is the exact opposite of the marked T2 hyperintensity of pleomorphic adenoma and is critically important in differential diagnosis. Proteinaceous or cholesterol-rich fluid in cystic cavities can produce T1 hyperintensity. The embryological association of heterotopic salivary gland tissue with lymphoid tissue in the parotid tail explains the specific localization and tendency for bilateral/multifocal occurrence. Smoking triggering chronic inflammation that stimulates oncocytic metaplasia and lymphoid hyperplasia explains the strong epidemiological association with smoking.
In Warthin tumor, Tc-99m pertechnetate is actively accumulated through Na⁺/I⁻ symporter (NIS) expression of oncocytic cells, creating a hot nodule. This finding is nearly pathognomonic among salivary gland tumors — only Warthin tumor and oncocytoma show pertechnetate uptake. All other salivary gland tumors including pleomorphic adenoma appear as cold nodules.
On T2-weighted sequences, Warthin tumor shows intermediate-to-low signal; this finding clearly differentiates from the marked T2 hyperintensity of pleomorphic adenoma. The dense cellularity of lymphoid stroma and proteinaceous cystic fluid shorten T2 relaxation time, producing intermediate signal. Hemorrhage or dense proteinaceous material in cystic cavities may produce even lower T2 signal. Solid components generally appear isointense or mildly hypointense to muscle. This T2 signal pattern is the most valuable single MRI criterion for distinguishing Warthin tumor from pleomorphic adenoma and has accuracy exceeding 90%.
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The mass in the parotid tail demonstrates intermediate-to-low signal on T2-weighted sequences; this signal pattern is more consistent with Warthin tumor than pleomorphic adenoma.
On T1-weighted sequences, the cystic components of Warthin tumor typically show hyperintense signal; this finding results from proteinaceous or cholesterol-rich fluid content in cystic cavities. Solid components appear isointense or mildly hypointense to muscle on T1. Focal high T1 signal may be observed with internal hemorrhage. Fluid-fluid levels may be seen — upper portion proteinaceous/hemorrhagic fluid (T1 hyperintense), lower portion serous fluid (T1 hypointense). This T1 hyperintense cystic component finding increases diagnostic accuracy when evaluated together with T2 intermediate signal.
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The cystic components of the lesion demonstrate hyperintense signal on T1-weighted sequences; this finding is consistent with proteinaceous/hemorrhagic cystic content and supports Warthin tumor.
On contrast-enhanced CT, Warthin tumor appears as a cystic-solid mixed mass in the parotid tail. Solid components show homogeneous enhancement. Cystic areas may be of fluid density or slightly hyperdense due to proteinaceous content. The tumor is generally well-defined and may show lobulated contours. In bilateral involvement, symmetric or asymmetric masses are seen in both parotid tails. On non-contrast CT, the solid component has soft tissue density (30-50 HU). Calcification is rare. Surrounding fat tissue planes are preserved — this finding supports benignity.
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A well-defined cystic-solid mixed mass is identified in the parotid tail, with solid components demonstrating homogeneous enhancement on post-contrast series; location and morphology are consistent with Warthin tumor.
On B-mode ultrasonography, Warthin tumor typically appears as a well-defined, oval or round, cystic-solid mixed mass in the parotid tail. Cystic areas may be anechoic or contain low-level internal echoes (proteinaceous content). The solid component appears hypoechoic or isoechoic. A multicystic pattern with thin septa is commonly seen. In bilateral involvement, similar-appearing masses are found in both parotid tails — this finding is highly specific for Warthin tumor. During inflammatory episodes, the tumor margins may become indistinct and periglandular edema may be seen. Posterior acoustic enhancement may be observed due to the cystic component.
Report Sentence
A well-defined mass with cystic-solid mixed echopattern is identified in the parotid tail, with thin septal structures and posterior acoustic enhancement; consistent with Warthin tumor.
On Tc-99m pertechnetate scintigraphy, Warthin tumor demonstrates prominent radiotracer uptake (hot nodule). This finding results from active pertechnetate uptake through the Na⁺/I⁻ symporter (NIS) on the basolateral membrane of oncocytic cells. Warthin tumor is one of only two salivary gland tumors showing pertechnetate uptake (the other being oncocytoma). On delayed images (30-60 minutes), uptake persists because oncocytic cells continue to actively retain pertechnetate intracellularly. This finding has specificity exceeding 95% for distinguishing from pleomorphic adenoma (cold nodule). SPECT/CT fusion more precisely localizes the uptake.
Report Sentence
On Tc-99m pertechnetate scintigraphy, the mass in the parotid tail demonstrates prominent radiotracer uptake (hot nodule); this finding is consistent with Warthin tumor or oncocytoma.
On FDG PET-CT, Warthin tumor typically shows moderate-to-high FDG uptake (SUVmax typically 3-8). The high metabolic activity of oncocytic cells (abundant mitochondria, high glucose metabolism) is the primary cause of FDG uptake. This FDG avidity may confuse Warthin tumor with malignant tumors — false positive results have been reported, particularly with metastatic lymph nodes or lymphoma. Cystic components show low FDG uptake; heterogeneous uptake pattern (high in solid areas, low in cystic areas) may be a diagnostic clue. Symmetric FDG uptake in bilateral parotid tails strongly suggests Warthin tumor.
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On FDG PET-CT, the mass in the parotid tail demonstrates moderate-to-high FDG uptake (SUVmax: [value]); this finding alone is insufficient for benign-malignant differentiation but Warthin tumor should be primarily considered in the presence of bilateral uptake.
On diffusion-weighted imaging, Warthin tumor typically shows diffusion restriction; ADC values are relatively low (typically 0.8-1.2 × 10⁻³ mm²/s). The dense cellularity of lymphoid stroma and compact arrangement of oncocytic cells cause intracellular water restriction. These low ADC values clearly separate from pleomorphic adenoma (ADC >1.5 × 10⁻³ mm²/s) but may overlap with malignant tumors. The combination of T2 intermediate signal + low ADC is highly specific for Warthin tumor. In cystic components, ADC values are higher and reflect fluid diffusion.
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The lesion demonstrates true diffusion restriction on diffusion-weighted sequences with low signal on ADC maps (ADC: [value] × 10⁻³ mm²/s); combined with T2 intermediate signal, these findings are consistent with Warthin tumor.
Criteria
Typical Warthin tumor containing both cystic and solid components. Most common form (70-80%).
Distinct Features
Well-defined cystic-solid mixed mass, intermediate-to-low T2 signal, T1 cystic component hyperintensity, thin septa, posterior acoustic enhancement, pertechnetate uptake. Located in parotid tail.
Criteria
Variant with predominant solid component and minimal cystic component. Less common (10-15%).
Distinct Features
Homogeneous solid mass, intermediate T2 signal, prominent enhancement, decreased posterior acoustic enhancement. May mimic pleomorphic adenoma but T2 hyperintensity is absent and pertechnetate uptake is present. ADC values are low.
Criteria
Warthin tumor in both parotid glands and/or multiple foci in the same gland. Seen in 10-20% of patients.
Distinct Features
Similar-appearing cystic-solid masses in both parotid tails. May be synchronous or metachronous. This feature is highly distinguishing from other salivary gland tumors. Bilateral involvement nearly confirms the diagnosis.
Criteria
Warthin tumor that has undergone or is undergoing acute inflammatory episode. Presents with pain, swelling, redness.
Distinct Features
Blurred tumor margins, periglandular fat infiltration, surrounding edema, debris in cystic cavities, wall thickening. May mimic inflammatory acute sialadenitis or abscess. Aspiration fluid is usually dark brown (old hemorrhage + cholesterol crystals).
Distinguishing Feature
Pleomorphic adenoma is markedly hyperintense on T2 (Warthin is low-intermediate), has high ADC (Warthin has low ADC), no pertechnetate uptake (Warthin is hot nodule), usually unilateral/unifocal, anywhere in the parotid superficial lobe (Warthin in tail).
Distinguishing Feature
Oncocytoma also shows pertechnetate uptake (hot nodule — oncocytic cells) but is usually solid, with minimal cystic component, unilateral/unifocal, and rarer than Warthin. T2 signal level on MRI may be similar but absence of cystic component is distinguishing.
Distinguishing Feature
Low-grade mucoepidermoid carcinoma may also be cystic-solid but does not show pertechnetate uptake, cystic component may show hyperintensity on T1 due to mucinous content, does not have specific localization to the parotid tail, and is usually unilateral.
Distinguishing Feature
Lymphoma is solid and homogeneous, no cystic component, shows low T2 signal and very low ADC. MALT lymphoma may develop in the setting of Sjögren syndrome. Bilateral parotid involvement may occur but diffuse infiltration pattern dominates rather than cystic-solid mixed structure.
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
Preoperatif İİAB tanı doğrulama için yapılabilir ancak zorunlu değildir. Asemptomatik hastalarda konservatif izlem de kabul edilebilir. Cerrahi gerektiğinde süperfisiyal parotidektomi uygulanır. Malign dönüşüm riski <1% olduğundan acil cerrahi endikasyonu yoktur.Warthin tumor is a benign tumor with extremely low risk of malignant transformation (<1%). Conservative follow-up or surgical treatment options are available for asymptomatic patients. Surgical indications: cosmetic concerns, size increase, recurrent inflammatory episodes, or suspicion of malignancy. Superficial parotidectomy is the standard surgical approach; facial nerve must be preserved. Recurrence rate is low (2-5%). FNAB can be performed for diagnostic purposes; aspirate typically contains dark-colored fluid (proteinaceous, with cholesterol crystals) and oncocytic cells + lymphocyte layer. Contralateral parotid follow-up is recommended in the presence of bilateral involvement.
Superficial parotidectomy is the treatment option. Risk of malignant transformation is very low (<1%). May be bilateral or multifocal.