Imaging of benign salivary gland tumors under the fifth WHO classification, with a focus on rare histologic types and newly listed entities—Part II

The World Health Organization (WHO) Classification of Head and Neck Tumors was updated from the fourth edition (published in 2017) to the fifth edition (published in 2024). The current WHO classification lists 15 benign and 21 malignant epithelial salivary gland tumors (SGTs). Among the benign epithelial tumors, four entities are newly listed: intercalated duct adenoma/hyperplasia, striated duct adenoma, sclerosing polycystic adenoma, and keratocystoma. This second article in a two-part review series summarizes the four newly listed benign SGTs, focusing on their classification background, clinicopathologic features, and reported imaging findings. As the published imaging literature remains limited, radiologic-pathologic correlation remains essential for recognizing these rare entities and avoiding overinterpretation of benign lesions. The aims of this review are to clarify the currently recognized imaging features of these rare tumors while emphasizing the need for careful integration of imaging, histopathologic, immunohistochemical, and molecular findings.