Lymphomatous papillary cystadenomas (Warthin tumors)

• Well-defined, heterogeneous solid-cystic lesion in the parotid tail/superficial lobe of the parotid gland
• Presence of a mural nodule within cystic components—strongly suggestive feature
• Multiple sponge-like anechoic or low-attenuation areas within an ovoid mass with sharp margins
• Bilateral or multifocal parotid masses in an older male patient

• Ultrasound: Ovoid mass with well-defined margins, multiple irregular sponge-like anechoic areas, and increased vascularity; larger lesions (>5 cm) tend to have greater cystic content and may be nearly entirely cystic.
• CT: Well-defined heterogeneous solid-cystic lesion in the superficial lobe or parotid tail without calcification; cystic changes appear as lower attenuation intralesional areas with moderate enhancement of solid components; mural nodules are strongly suggestive of Warthin tumor.
• MRI T1: Low to intermediate signal intensity with potential focal high signal from cholesterol-containing cyst components.
• MRI T2: Heterogeneous and variable signal intensity reflecting the mixed solid-cystic nature.
• MRI T1 post-gadolinium: Cystic components do not enhance while solid parts demonstrate enhancement, allowing clear delineation of solid versus cystic components.
• Nuclear medicine: Characteristic uptake on Tc99-pertechnetate, thallium, and FDG-PET imaging, reflecting the lymphoid origin of these tumors.
• Size and distribution: Usually small (1–4 cm), favor the parotid tail at the mandibular angle level, with tendency for multicentric presentation in up to 20% of cases.
• Greater propensity for cystic change than any other salivary gland tumor, with cystic components seen in approximately 30% of cases.

• Pleomorphic adenoma: The most common benign parotid tumor; typically homogeneous or minimally heterogeneous without the characteristic sponge-like cystic pattern and mural nodules seen in Warthin tumors.
• Mucoepidermoid carcinoma: Malignant tumor with more aggressive features, invasion, and typically heterogeneous appearance; clinical context and lack of benign features distinguish from Warthin.
• Adenoid cystic carcinoma: Malignant salivary gland tumor with perineural invasion and different imaging characteristics; typically lacks the distinctive cystic heterogeneity of Warthin tumors.
• Acinic cell carcinoma: Salivary gland malignancy with different signal characteristics and clinical presentation; benign imaging features and multicentric bilateral presentation favor Warthin.
• Parotid lymphoma or benign lymphoepithelial lesions: Can mimic Warthin tumor but lack the sharply demarcated mural nodules and typical sponge-like cystic pattern.
• Sjögren syndrome: Causes bilateral multifocal parotid involvement but typically produces smaller punctate cystic foci (punctate sialoadenopathy) rather than large well-defined masses with mural nodules.

Describe as: "Well-defined heterogeneous mass in the parotid tail with mixed solid and cystic components, characterized by sponge-like anechoic/low-attenuation areas and enhancement of solid portions—findings consistent with Warthin tumor. Note presence and location of any mural nodules, which are highly suggestive. Always specify if bilateral or multifocal masses are present, and recommend correlation with smoking history and age (typically 6th decade)."

• Mistaking the heterogeneous solid-cystic appearance for a malignancy or complex cyst; the presence of a sharply defined mural nodule is a reassuring benign feature rather than a malignant sign in this context.
• Overlooking bilateral or multifocal disease, which occurs in up to 20% of cases and is the most common cause of multiple solid parotid masses; always image both glands.
• Confusing Warthin tumor with pleomorphic adenoma on imaging; the sponge-like cystic heterogeneity and mural nodules favor Warthin, while pleomorphic adenomas tend to be more homogeneous.
• Failure to correlate with clinical history (smoking, radiation, older age, male gender) and ectopic locations (submandibular gland, larynx, oral cavity); small percentage occur outside the parotid.