Hybrid intercalated duct lesion of the parotid: A case report.

Background: Intercalated duct lesions (IDLs) are considered relatively benign and rare tumors of salivary glands, that were only described recently. Their histopathological appearance may range from ductal hyperplasia to encapsulated adenoma with hybrid patterns of both variants. It is thought that IDLs may be the precursor for malignant proliferations, therefore their correct diagnosis remains crucial for proper lesion management. It is the first reported IDL case arising from the accessory parotid gland (APG), which stands for less frequent but higher malignancy rate tumor developmental area.

Case Summary: A 24-years-old male with no accompanying diseases was referred to the hospital with a painless nodule on the right cheek. On physical examination, the stiff, immobile, and painless mass was palpable in the anterior portion of the right parotideomasseteric region, just superior to the parotid duct. Ultrasound examination demonstrated 1.5 cm × 1.0 cm hypoechogenic mass on the anterior part of the right parotid gland. Ultrasound-guided fine needle aspiration cytology, followed by liquid-based fine needle aspiration biopsy were performed. However, the results were uninformative. A contrast-enhanced magnetic resonance imaging (MRI) of the parotid was obtained, demonstrating a 1.5 cm × 1.0 cm × 0.5 cm tumor with high intensity capsule together with low intensity core in the very anterior part of right superficial lobe, situated in the APG. An MRI features were uncharacteristic to common parotid tumors, therefore surgical resection followed up. After histopathological examination, the final diagnosis of hybrid IDL was confirmed.

Conclusion: Fine needle aspiration biopsy might not always be diagnostic, and given the malignant potential, the surgical resection of such lesion remains the treatment of choice.