CD56-POSITIVE DIFFUSE LARGE B CELL LYMPHOMA: COMPREHENSIVE ANALYSIS OF CLINICAL, PATHOLOGICAL AND MOLECULAR CHARACTERISTICS WITH LITERATURE REVIEW.

CD56-positive DLBCL

Abstract

BACKGROUND: Diffuse large B-cell lymphoma, NOS (DLBCL, NOS) is the most common non-Hodgkin lymphoma. Expression of CD56 in DLBCL, NOS is highly unusual. Little is known about  its incidence and clinical importance. So far, no genetic profiling was performed in CD56 positive DLBCL, NOS.

MATERIALS AND METHODS: Tissue microarrays have been constructed, sectioned and stained by H&E and immunohistochemistry for 229 patients with DLBCL diagosed 2008-2017. For CD56 positive cases, clinical data were gathered including age at diagnosis, stage of the disease, IPI score, treatment scheme and number of cycles, radiotherapy treatment, treatment outcome and possible relapse of the disease. Overall survival (OS) and progression-free survival (PFS) were calculated. For four patients, RNA was extracted and targeted RNA (cDNA) sequencing of 125 genes was performed with Archer FusionPlex Lymphoma kit.

RESULTS: CD56 expression was found in 7 cases (3%). Intensity of expression varied from moderate focal up to very intensive and diffuse. All patients had de novo DLBCL. Median age at diagnosis was 54.5 years. Five of them were females and 2 males. According to the Hans algorithm, 6 patients had GBC type and one non-GBC (ABC) type, double expressor. Genetic profiling of four patients according to the Schmitz classification, showed that 1 case was of BN2 subtype, 1 of EZB subtype, 2 were unclassified. All 6 treated patients reached a complete response and experienced no progression of the disease in the median follow up period of 80.5 months.

CONCLUSION: We report on one of the largest series of CD56+DLBCL, NOS with detailed clinico-pathological data and for the first time described genetical findings in a limited number of patients. Our results show that CD56 expression is rare but present in prognostically favourable subtypes of DLBCL, NOS as tested by immunohistochemical or genetic profiling.