Distribution and ZAP-70 expression of WHO lymphoma categories in Shanxi, China: a review of 447 cases using a tissue...

This study aims to assess the distribution of lymphoma subtypes in Shanxi, China, according to the World Health Organization (WHO) classification, and to compare the relative distribution with other areas of the world. H&E-stained tissue sections from the archives of the Shanxi Tumor Hospital, China, were reviewed and 447 cases with sufficient materials were selected for detailed study. A panel of antibodies and probes was assembled, including antibodies to ALK1, bcl-6, CDs 1alpha, 3, 4, 5, 7, 8, 10, 15, 20, 23, 30, 43, 56, 68, 79alpha, and 99, cyclin D1, EMA, kappa, lambda, LMP1, PAX5, TdT, Vs38C and ZAP70, plus EBER RNA probe by in situ hybridization. The 447 lymphoma cases, subtyped according to the WHO classification, were assembled in triplicate into 11 tissue microarrays and examined with the panel of markers described. Among the 447 cases, 385 (82.6%) were confirmed to be non-Hodgkin lymphomas (NHL) and 62 (13.9%) were Hodgkin lymphomas of classic type (CHL). Of the NHL cases, 68.6% were B-cell lymphomas and 30.6% T/NK-cell lymphomas. Histiocytic neoplasms accounted for only three cases (0.8%). Diffuse large B-cell lymphomas (DLBCL) were the most common subtype (35.1%), followed by peripheral T-cell lymphomas unspecified (PTun, 12.0%), extranodal marginal zone B-cell lymphomas (MALT lymphomas, 11.7%), follicular lymphomas (FL, 8.6%), T-lymphoblastic lymphomas (T-LBL, 7.0%), anaplastic large cell lymphomas (ALCL, 4.2%), B small lymphocytic lymphomas (B SLL, 3.6%), and mantle cell lymphomas (MCL, 2.6%). Of 263 B-cell neoplasms, 105 (39.9%) expressed immunoglobulin light chain, including 52 kappa and 53 lambda, detectable in paraffin sections. The incidence of DLBCL was similar to many Western countries and Asia. The frequency of FL was, however, much lower than the usual pattern in Western countries, although NK/T-cell lymphomas were more common (30.6%), similar to other countries in Asia, including Japan and Korea. With regard to markers of EBV infection, 8 of 385 (2.1%) NHL cases gave positive findings by both in situ hybridization (EBER RNA) and immunohistochemistry (LMP-1), whereas 24 (6.2%) expressed only the EBER and 12 (3.1%) expressed only LMP-1. EBV positivity was found in 24 of 119 (20.2%) T and NK cell lymphomas, in 20 of 263 (7.6%) B cell neoplasms, and in 37 of 62 (59.7%) CHLs. In CHLs there was complete concordance of results by both in situ hybridization (EBER RNA) and immunohistochemistry (LMP-1) procedures. ZAP70 was detected in most T cell-lineage disorders (61.4%) and also in a subset of B small lymphocytic lymphomas (50%). However, ZAP-70 was expressed in a minority of other types of B-cell lymphomas, including precursor B-cell acute lymphoblastic leukemia (25%), diffuse large B-cell lymphoma (26.7%), follicular lymphoma (15.2%), and lymphoplasmacytic lymphoma (9.1%). Immunohistochemical analysis represents an effective method for assessing ZAP-70 expression and reveals that a variety of B-cell malignant neoplasms express ZAP-70, albeit at low frequency.