|S/no.||Diagnostic points and pitfalls|
|1.||B-immunoblasts in infectious mononucleosis can show clustering and/or be HRS-like. This can lead to a misdiagnosis of DLBCL or CHL.|
|2.||Reactive immunoblasts can show variable expression of CD45/LCA and B cell markers, resembling HRS cells of CHL.|
|3.||In some extranodal sites, eg, spleen, circulating activated CD8-positive T cells can be present in large numbers and be morphologically and immunophenotypically atypical, thus mimicking T cell lymphoma.|
|4.||Molecular clonality studies in infectious mononucleosis may show an oligoclonal/clonal band/peak. This, combined with an atypical morphology, may lead to an erroneous diagnosis of lymphoma, which can be avoided by close correlation with clinical and serological findings.|
CHL, classical Hodgkin lymphoma; DLBCL, diffuse large B cell lymphoma; HRS, Hodgkin/Reed-Sternberg; LCA, leucocyte common antigen.