Pitfalls in the pattern of bone marrow infiltration in lymphoproliferative disorders

Diagnostic pitfalls in the biopsies of bone marrow (BM) involved in lymphoproliferative disorders may not be recognized by the pathologist, unless he is aware of them. Apparently uninvolved BM may prove to be infiltrated by neoplastic cells after immunohistochemistry or molecular techniques are applied. Moreover, overlap in the immunophenotypical profile between different lymphoma subtypes and the established exclusiveness of BM patterns of involvement in certain lymphomas, may lead to diagnostic underestimation or overinterpretation. This article approaches the pitfalls in a systematic way, focusing primarily on the pattern of BM involvement in lymphoproliferative lesions as a potentially misleading diagnostic parameter. In this context, the presentation and discussion of pitfalls in terms of 'what should be considered' by the pathologist are preceded by a brief outline of 'what is known' for each disease entity that pitfalls refer to.