In association to our undestanding of the pathogenesis and biopsy diagnosis of mantle cell lymphoma using immunohistochemical detection of cyclin D1 expression and/or FISH detection of t(11;14)(q13;q32) all the lymphomas interfering with these factors are discussed in a form of a review. This includes a cyclin D1 negative mantle cell lymphoma, as well as other than MCL lymphomas showing positive intranuclear cyclin D1 positivity due to the changes either at transcriptional or postranscriptional levels. In addition to the MCL, the cyclin D1 positivity might be detected in the cells of hairy cell leukemia, plasmocytic lymphoma and diffuse large B-cell lymphoma. In the first two lymphomas the differential diagnostic problems usually do not arise (with exception of G3 plasmacytoma) and cyclin D1 expression might be of interess to understand better their biology, or to represent a prognostically significant factor. In contrast, cyclin D1 positivity in diffuse large B-cell lymphomas demonstrates the possible role of cyclins in the pathogenesis of this lymphoma and may lead to the problems of the differential diagnosis of aggressive variant of pleomorphic MCL (especially when occuring with CD5 positivity coexpression ). The review includes discussion related to the significance of cyclin D1 positivity and to the approach in the immunohistochemical and FISH analysis of the biopsy material.