hodgkin lymphoma and anaplastic variants of non-hodgkin lymphoma

background and objectives: classic hodgkin lymphoma (chl), anaplastic large cell lymphoma (alcl) and some cases of diffuse large b cell lymphoma (dlbcl) have overlapping morphologic features. since they all represent distinct clinico-pathologic entities, we explored the differential diagnostic impact of immunophenotyping to discriminate between them. materials and methods: we included 61 cases diagnosed as chl, alcl, and anaplastic variant of dlbcl. we reviewed morphologic microscopic findings by conventional staining and immunohistochemistry (ihc) with antibodies against pax-5, cd30, cd15, cd45, ema, alk-1, and lmp-1. results: fifty cases corresponded to chl (81.97%), 4 cases to alcl (6.56%), and 4 cases to dlbcl (6.56%) excluding 3 cases, which remained unclassifiable (4.92%). pax-5 was expressed in 94% of chl and 100% of dlbcl cases. lmp-1 was expressed in 52% of chl and 25% of dlbcl cases. ema was invariably expressed in all 4 cases of alk+alcl. it was expressed in 4/50 cases (8%) of chl and in 2/4 cases (50%) of dlbcl. cd45 was expressed in all cases of alcl and dlbcl but also in 3/50 cases (6%) of chl. conclusion: the differentiation between alcl and chl based on ema and cd45 is not reliable. utilization of pax-5 in combination with other markers such as cd15 and lmp-1 is recommended. cd20 and pax-5 are not too helpful in the differentiation of chl and dlbcl, while cd15 and cd79a were found to be quite useful discriminative markers for this purpose.