Pitfalls in Classifying Lymphomas
Tawatchai Pongpruttipan MD*, Panitta Sitthinamsuwan MD*, Pimpattana Rungkaew MD*, Ruchira Ruangchira-urai MD*, Akkrarash Vongjirad MD*, Sanya Sukpanichnant MD*
Affiliation : * Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University
Background : Although the WHO classification (2001) requires a great deal of morphologic, immunophenotypic,
genetic, and clinical features for classifying lymphomas, it is still feasible to misdiagnose under limited
resources, especially a limited panel of antibodies used for immunophenotyping. To identify pitfalls in classi-
fying lymphomas among hematopathologist, general pathologists, and pathology residents under this situa-
tion.
Materials and Methods : Newly diagnosed lymphoma cases from 1 July 2002 to 30 June 2003 at Siriraj Hospital
were included for two rounds of individually blinded review by a hematopathologist, two general patholo-
gists, and three pathology residents. Final diagnoses were given by consensus. Pitfalls were determined from
misdiagnosis, in each case analyzed in terms of frequency.
Results : One hundred and four lymphoma cases included 61 diffuse large B-cell lymphoma (DLBCL, 58.6%),
12 MALT lymphoma (11.5%), eight follicular lymphoma (FL, 7.7%), seven classical Hodgkin lymphoma (HL,
6.7%), four unspecified peripheral T-cell lymphoma (PTCL, 3.8%), three Burkitt lymphoma (BL, 2.9%), two
subcutaneous panniculitis-like T-cell lymphoma (SPTCL, 1.9%), and seven other uncommon types (1% each).
Pitfalls were low in frequency on diagnosis of DLBCL, nodular sclerosis HL, and SPTCL (8% each), but not
different among the participants only in DLBCL. Pitfalls in diagnosis of MALT lymphoma, mixed cellularity
HL, BL, unspecified PTCL, and FL were 60%, 50%, 33%, 29%, and 24%, respectively. However, considering
hematopathologist and non-hematopathologist groups, pitfalls in the former were lower, especially in the
uncommon types of lymphoma.
Conclusion : Pitfalls in classifying lymphomas are common. Interest in hematopathology reduces misdiagno-
sis in lymphomas other than DLBCL.
Keywords : Misdiagnosis, Pitfall, Lymphoma, Pathology, WHO Classification
