Cutaneous B cell lymphomas: standards in diagnostic and clinical work‐up. Hints, pitfalls and recent advances

Abstract

Cutaneous B cell lymphomas: standards in diagnostic and clinical work-up. Hints, pitfalls and recent advances This review focuses upon the pragmatic diagnostic approach of suspicious B cell infiltrations in the skin and lists the necessary histopathological and molecular tools for a thorough work-up. We start with the description of different histopathological patterns of cutaneous B cell infiltrations and recommend patterndependent immunohistochemical staining algorithms for further differential diagnosis. A summarised description of the current World Health Organisation (WHO) subtypes of primary cutaneous B cell lymphomas highlighting their most relevant clinical, histopathological and molecular features is included.Differential diagnostic clues towards secondary infiltrations by systemic B cell lymphomas, B cell-rich T cell lymphoproliferative disorders and pseudolymphomas are provided. Furthermore, the most important pitfalls also elaborating on rare differential diagnoses are highlighted with helpful hints to solve arising diagnostic difficulties. The clinical work-up and the staging examinations depending on the type of B cell infiltrate are relevant for patient care and a short overview of the main diagnostic standards is given.

Cyclin D1 expression, cell proliferation, and clonal persistence characterize primary cutaneous CD4+ small or medium T‐cell lymphoproliferative disorder

“…However, in contrast to previous reports, we do not believe that the presence of clonal plasma cells and/or clonal immunoglobulin gene rearrangements in PCSM‐LPD is a recurrent phenomenon 5,17 . Primary cutaneous marginal zone lymphomas frequently harbour light‐chain‐restricted plasma cells and may present with abundant reactive CD4(+) and PD1(+)‐cells 18–20 . Whilst single cases with overlapping features of T‐and B‐cell lymphoproliferative disorders certainly exist, we cannot confirm this overlap to be a recurrent finding in our study.…”

“…5,17 Primary cutaneous marginal zone lymphomas frequently harbour light-chain-restricted plasma cells and may present with abundant reactive CD4(+) and PD1(+)-cells. [18][19][20] Whilst single cases with overlapping features of T-and B-cell lymphoproliferative disorders certainly exist, we cannot confirm this overlap to be a recurrent finding in our study. The discrepancies between our data and the published data with respect to B-cell clonality may be due to our inclusion criteria, as we systematically excluded marginal zone lymphomas by staining for light chains and/or additional BCR-clonality analysis.…”