Special mesenchymal neoplasms of the head and neck: Update from the 2022 WHO

Abstract

Similar to the approach adopted in the classification of tumors in other organs, anew feature of the current Word Health Organization (WHO) classification of the head and neck tumors is the exclusion of soft tissue tumors from single organs and their inclusion in aseparate chapter devoted to them. This applies to tumors that are principally ubiquitous but show apredilection for the head and neck sites. The only exception to this rule represents those entities that are almost restricted to aspecific head and neck site/organ (such as nasopharyngeal angiofibroma, sinonasal glomangiopericytoma, and biphenotypic sinonasal sarcoma), which remain in their respective organ chapters. Included among soft tissue tumors are some old but still underrecognized entities, such as phosphaturic mesenchymal tumors, and newly defined entities, such as GLI1-altered tumors. The aim of including these entities is to enhance recognition of these uncommon but likely under-recognized entities to better characterize them in the future. This review summarizes the main features of these rare entities and discusses their differential diagnoses.