A 13 year old boy presented with a huge mass on his right arm of 6 months duration. Histopathological examination revealed sheets of malignant small round blue cells with immunopositivity for LCA, CD43, CD45Ro, CD30, EMA, ALK-1 and CD99, and negativity for CD20, TdT, myogenin, myoD1, NSE, bcl-6, bcl-2 and CD10. Fluorescent In-Situ Hybridization (FISH) testing excluded the diagnosis of Ewing's sarcoma/PNET. Pathologists need to be aware of the diagnosis of a small cell variant of ALCL, as well as of the fact that CD99 expression commonly occurs in cases of ALK-positive ALCL, in order to distinguish this entity from Ewing's sarcoma/PNET.
Matched MeSH terms: Lymphoma, Large B-Cell, Diffuse/immunology*
Recent reports have divided diffuse large B cell lymphoma (DLBCL) into germinal centre B cell-like and activated B cell-like subgroups with implicated differences in prognosis.
Matched MeSH terms: Lymphoma, Large B-Cell, Diffuse/immunology