Overlapping morphologic and immunophenotypic profiles in small B-cell lymphoma. A report of two cases

Abstract

We present two cases of small B-cell lymphomas of particular diagnostic interest because the histological patterns were at variance with their immunophenotype. One of these lymphomas, involving the gallbladder and duodenum, showed a marginal zone lymphoma-like (MALT type) pattern of cellular infiltration with CD5 negativity but (unexpectedly) Cyclin D1 positivity. Fluorescence in situ hybridization analysis of this case was performed because of the aberrant expression of Cyclin D1, and was clearly positive for the Cyclin D1 gene translocation. The second case, occurring in a lymph node, showed the typical growth pattern of a follicular lymphoma but it had an atypical immunophenotype, namely, expression of Cyclin D1, CD10, and Bcl2 and focally Bcl6, accompanied by a lack of CD5 and CD23. The Cyclin D1 gene translocation was detected by fluorescence in situ hybridisation (FISH), whereas c-myc and Bcl2 genes translocation were absent. Numerical chromosomal changes, which were visualized for chromosomes 8, 11, and 18 could be correlated to the aberrant immunoprofile. In this context, we discuss the diagnostic value of Cyclin D1, CD5, CD23, CD10, Bcl6 markers revealed by immunohistochemistry, as well as the significance of detection by FISH of chromosomal translocations such as t(11;14) and t(14;18). The question still remains as to whether such cases should be designated as specific lymphoma entities or reported as unclassifiable and the chromosome aberration reported.

A low-grade follicular lymphoma with strong expression of cyclin D1, but without evidence of CCND1 translocation or amplification

“…In contrast to two cases classified as cyclin D1-positive follicular lymphomas, which harboured CCND1 translocation1 2 and could be perhaps regarded as hybrid tumours sharing genetic and immunophenotypic features of a follicular lymphoma and a mantle lymphoma, this case presented otherwise all classical characteristics of a low-grade follicular lymphoma, including non-translocated CCND1. Its morphology in tinctorial stains was virtually diagnostic on its own, with very well defined follicles, dominated by centrocytes, but also containing unmistakable centroblasts, and it carried translocated BCL2.…”

How I treat: diagnosing and managing “in situ” lymphoma

“…These probably represent a divergent evolutionary pathway, possibly dictated by a different set of secondary events distinct from those seen in overt MCL. 25,31 Patients with "in situ" MCL need proper evaluation to exclude the coexistence of overt MCL. In the absence of coexisting overt MCL, the clinical impact of the diagnosis is doubtful and close follow-up is essential.…”

Early Lymph Node Involvement by Mantle Cell Lymphoma Limited to the Germinal Center

“…While unusual, a follicular growth pattern has also been described, which morphologically mimics follicular lymphoma. [1][2][3] In addition to mimicking other B-cell lymphomas, MCL may occasionally mimic reactive follicular hyperplasia. A subtle mantle zone growth pattern is well known, in which neoplastic lymphocytes are present only in widened mantle zones.…”