A potential diagnostic pitfall for hobnail variant of papillary thyroid carcinoma

Aims Hobnail variant of papillary thyroid carcinoma (PTC) is an aggressive PTC subtype characterised by a hobnail cytomorphology. However, some classic PTC have a ‘hobnail‐like’ cytomorphology associated with thick, hyalinised, variably oedematous fibrovascular cores that appears to be a form of ischaemic/degenerative atypia. Methods and results We studied three cohorts to compare the histopathological characteristics and clinical outcome of...