title: Is there a spectrum of cytologic atypia in type a thymomas analogous to that seen in type B thymomas? A pilot study of 13 cases.
abstract: Thirteen cases of type A thymoma are reported showing the characteristic architectural attributes of this tumor type (World Health Organization), such as lobulation, perivascular spaces, gland-like formations, and cystic changes, but also displaying atypical features, as defined by increased mitotic activity, mild to moderate nuclear atypia, and/or scattered small foci of necrosis. The tumors were similar to type B3 thymomas in many respects, except for the fact that the tumor cells were spindled instead of round/polygonal. The existence of these cases suggests the desirability of an expansion of the type A thymoma category, analogous to that currently used for type B tumors. The various nomenclature options that could be used to name these tumors have been discussed.
authors.affiliation: Department of Histopathology, The Christie Hospital, NHS Foundation Trust, Wilmslow Road, Manchester, UK. DNonaka@msn.com
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nonaka
authors.forename: Juan
authors.initials: J
authors.lastname: Rosai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002467:Cell Nucleus / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008938:Mitosis; D010865:Pilot Projects; D009626:Terminology as Topic; D013934:Thymectomy; D013945:Thymoma / Q000145:classification / Q000473:pathology* / Q000601:surgery; D013950:Thymus Gland / Q000473:pathology* / Q000601:surgery; D013953:Thymus Neoplasms / Q000145:classification / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome