From the Journals

BCL expression intensity key in distinguishing FL lesions



Intensity of BCL2 expression, and to a lesser extent expression of t(14;18), may help distinguish common and indolent cutaneous lymphomas from poorer-prognosis cutaneous lesions secondary to systemic follicular lymphomas, results of a recent investigation show.

Strong expression of BCL2 was almost always associated with secondary cutaneous follicular lymphoma (SCFL), and infrequently associated with primary cutaneous follicular center-cell lymphoma (PCFCL), according to the study results.

The translocation t(14;18) was likewise linked to secondary lesions, occurring less frequently in PCFCL in the study, reported recently in the Journal of Cutaneous Pathology.

“BCL2 expression intensity is the single most valuable clue in differentiating PCFCL from SCFL cases on histopathological grounds,” said Ramon M. Pujol, MD, PhD, of Hospital del Mar, Barcelona, Spain, and colleagues.

One of the main cutaneous B-cell lymphoma subtypes, PCFCL is marked by frequent relapses, but little incidence of systemic spread, meaning that conservative, skin-based therapies are usually warranted. By contrast, patients with SCFLs have a poor prognosis and may require systemic therapy, the investigators noted in their report.

Previous investigations have yielded conflicting results on the role of BCL2 expression, CD10 expression, and presence of t(14;18) translocation in distinguishing PCFCL from SCFL.

While early studies suggested most PCFCLs were negative for these markers, some recent reports suggested BCL positivity in PCFCLs is as high as 86%, the investigators said.

Accordingly, Dr. Pujol and colleagues evaluated clinicopathologic and genetic features in a large series of patients, including 59 with PCFCL and 22 with SCFL.

Significant BCL2 expression was seen in 69% of PCFCLs and in 100% of SCFLs (P = .003) in this patient series; however, when looking at BCL2 intensity, investigators found strong expression almost exclusively in SCFL. Strong expression was seen in 46% of those patients with secondary lymphomas, versus just 4%, or two cases, in the PCFCL group (P = .001).

The t(14;18) translocation was seen in 64% of SCFLs and only 9.1% of PCFCLs (P = .001).

Similar to what was seen for BCL2, expression of CD10 was observed in 66% of PCFCLs and 91% of SCFLs, and again, intensity differences mattered. Strong CD10 expression was seen in 62% of secondary lymphomas and 16% of PCFCLs (P = .01). But the high number of positive PCFCLs made this marker less useful than BCL2, the investigators said.

“We believe that differences in BCL2 and CD10 expression between our results and older previous studies could reflect the improvement of antigen retrieval laboratory techniques,” they said.

The investigators did not report disclosures related to the research.

SOURCE: Servitje O et al. J Cutan Pathol. 2019;46:182-9.

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