SUBCUTANEOUS PANNICULITIS‐LIKE T‐CELL LYMPHOMA: MOLECULAR AND MUTATIONAL CHARACTERIZATION COMPARED WITH LUPUS PANNICULITIS AND HISTOPATHOLOGIC OVERLAPPING CASES

Abstract

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare cytotoxic primary cutaneous lymphoma whose histopathologic differential diagnosis with lupus erythematosus panniculitis (LEP) can be challenging, and overlapping cases have been described. In this study we investigate whether gene expression profiling using a customized NanoString platform may identify markers that can be used to improve our understanding of the disease and to make a more precise differential diagnosis. Twenty-two cases of SPTCL, LEP and overlapping cases were analyzed using a customized NanoString platform that includes 208 genes related to T-cell differentiation, stromal signatures, oncogenes and tumor suppressor genes. Unsupervised analysis of the gene expression of the samples identified three clusters of samples that differentiated SPTCL from LEP samples. Most overlapping cases (4/5) were clustered with LEP cases, and only one case was grouped with the SPTCL cases. We identified 60 and 30 genes that were respectively upregulated and downregulated in SPTCL compared with LEP. Differentially expressed genes were observed when comparing overlapping with LEP cases. Gene set enrichment analysis recognized gene sets defining each group. We identified mutations in epigenetic modificatory genes ARID1A, EZH2, TET2, DNMT3A, and NCOR1; the tumor suppressor gene TP53, and PLCG1 gene in four out of the six SPTCL samples analyzed. Only one case showed HAVCR2 mutation. In conclusion, SPTCL and LEP have distinctive molecular profiles. The molecular background of overlapping cases more closely resembles LEP than it does SPTCL. The research was funded by: Instituto de Salud Carlos III, from the Ministry of Science and Innovation of Spain, PI17/2172. Keywords: Diagnostic and Prognostic Biomarkers, Cutaneous non-Hodgkin lymphoma No conflicts of interest pertinent to the abstract.