Pathological features and types of T and NK cell lymphomas based on 152 cases

Objective To study the pathological features of T and NK cell lymphomas and the relative frequency of each type of these lymphomas.Methods 152 cases of T and NK cell lymphomas selected from archival tissues of lymphoid neoplasms diagnosed during the period of 1985～2005 were studied based on morphology,immunohistochemistry and in situ hybridization for Epstein-Barr virus(EBER) and correlated clinical findings,and reclassified according to new WHO classification(2001).Results The mean age of all the patients was 43 years old,ranged from 4 to 80 years old.The ratio of male to female was 3 to 1.There were 83 cases(54.6%) of extranodal lymphomas and 69 cases(45.4%) of nodal lymphomas.Ten types were identified in 152 cases of T and NK cell lymphoma.The most frequent type of the lymphoma was extranodal nasal NK/T cell lymphoma(52 cases,34.2%), followed by unspecified peripheral T cell lymphoma(31 cases,20.4%),precursor T lymphoblastic lymphoma(25 cases,16.4%) and anaplastic large cell lymphoma(21 cases,13.8%).Epstein-Barr virus was detected in 51 of 52 cases(98%) of extralnodal nasal NK/T cell lymphoma.Conclusions T and NK cell lymphomas show great morphological diversity.And each type has certain pathological features,which are the base of further classification.The most common type is extranodal nasal NK/T cell lymphoma.Frequency of T and NK cell lymphomas showed in this study in China is different from that in European and American countries,suggesting there may be different etiological factors.