EWSR1 and mesothelioma: Moreover, the EWSR1::ATF1 fusion is characteristic of hyalinizing clear cell carcinoma of the head and neck (HCCC; defined by distinctive morphology and epithelial/squamous cell immunophenotype) [10] and has been reported in a rare subset of conventional mesothelioma with predominance of epithelioid morphology and early age of onset [11].