Atypical mature bone in the otosclerotic otic capsule as the differentiated zone of an invasive osseous neoplasm

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumours of the Ear

In the recently published 5th Edition of the World Health Organisation Classification of Head and Neck Tumours, there are relatively few changes to report in terms of nomenclature in lesions of ear and temporal bone and fewer developments in molecular pathogenesis in comparison to other sites, particularly in sinonasal tract. Ear and temporal bone tumours are rare and biopsy material is limited. As a result, resources in the literature are scarce with few large series, no controlled clinical trials and the approaches to staging and management are not standardised. New entities are difficult to characterise. The number of entries has, however, increased for tumours of the ear and temporal bone (thirteen) compared to the 4th Edition (eleven). Some lesions previously included in the 4th Edition considered to have no site-specific features have been excluded to be discussed elsewhere and other benign lesions that are specific to this site have been included. The tumours and tumour-like entities of ear and temporal bone are discussed here mindful that the chapter in the 5th edition better correlates disease processes with clinical information and imaging and as far as possible standardises nomenclature.

Update From the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumours of the Ear

The 2017 fourth edition of the World Health Organization Classification of Tumours, specifically as it relates to the ear (Chap. 9), has several changes. Importantly, the number of entities has been significantly reduced by omitting tumors or lesions if they do not occur exclusively or predominantly at this site or if they are discussed in detail elsewhere in the book. These entities include: embryonal rhabdomyosarcoma, osteoma, exostosis, angiolymphoid hyperplasia with eosinophilia, Schneiderian papilloma, inverted papilloma, lipoma of the internal auditory canal, hemangioma, hematolymphoid tumors, and secondary tumors. Paraganglioma was included in the neck chapter. New entries include otosclerosis and cholesteatoma, while refinements to nomenclature, classification and criteria were incorporated into the ceruminous gland tumors and epithelial tumors of the middle and inner ear. Specifically, the middle and inner ear were combined, as practical limitations of origin and imaging make a definitive separation artificial. The classification reflects the state of current understanding for these uncommon entities, with this update only highlighting selected entities that were the most significantly changed.