Expression of TFH Markers and Detection of RHOA p.G17V and IDH2 p.R172K/S Mutations in Cutaneous Localizations of Angioimmunoblastic T-Cell Lymphomas

Am J Surg Pathol. 2017 Dec;41(12):1581-1592. doi: 10.1097/PAS.0000000000000956.

Abstract

Skin biopsies of 41 angioimmunoblastic T-cell lymphoma patients were retrospectively analyzed for the expression of follicular helper T-cell (TFH) markers, Epstein-Barr virus (EBV), and the presence of RHOA (p.G17V) and IDH2 (p.R172K/S) mutations using allele-specific polymerase chain reaction. We categorized cases into 4 distinctive patterns: (1) low-density lymphocytic perivascular infiltrates (n=11), (2) dense perivascular infiltrates with atypical cells and occasional inflammatory cells (n=13), (3) diffuse infiltrates reminiscent of angioimmunoblastic T-cell lymphoma (n=4), or (4) other aspects (n=13). Two EBV and 2 plasmacytoid lymphoproliferative disorders were seen. We observed variable expression of TFH markers (CD10 [50%], BCLB6 [84%], PD1 [94%], CXCL13 [84%], and ICOS [97.5%]), and EBV B-blasts (26%). A TFH phenotype was identified in 82% and 73%, respectively, of cases with the most challenging patterns 1 and 2. TFH markers and EBV can thus help for diagnosis and are detected in samples with low-density infiltrates. We found RHOA G17V and IDH2 R172K/S mutations in the skin in 14/18 (78%) and 3/16 (19%) cases, respectively. The RHOA G17V mutation was identified in a proportion of biopsies with patterns 1 and 2, which represent a diagnostic challenge. The RHOA G17V mutation was detected both in the skin and lymph node (LN) biopsies in 7/9 (64%) cases, and in only the skin or the LN of 1 sample each. The frequency of RHOA G17V mutation was similar to that reported in LNs. It may represent a sensitive diagnostic marker in the skin, helpful in cases with low-density infiltrates.

MeSH terms

  • Biomarkers, Tumor / analysis
  • Biomarkers, Tumor / genetics*
  • Chemokine CXCL13 / analysis
  • DNA Mutational Analysis / methods
  • Genetic Predisposition to Disease
  • Herpesvirus 4, Human / isolation & purification
  • Humans
  • Immunoblastic Lymphadenopathy / enzymology
  • Immunoblastic Lymphadenopathy / genetics*
  • Immunoblastic Lymphadenopathy / immunology
  • Immunoblastic Lymphadenopathy / pathology
  • Immunohistochemistry
  • Inducible T-Cell Co-Stimulator Protein / analysis
  • Isocitrate Dehydrogenase / genetics*
  • Lymphoma, T-Cell, Cutaneous / enzymology
  • Lymphoma, T-Cell, Cutaneous / genetics*
  • Lymphoma, T-Cell, Cutaneous / immunology
  • Lymphoma, T-Cell, Cutaneous / pathology
  • Mutation*
  • Neprilysin / analysis
  • Phenotype
  • Polymerase Chain Reaction
  • Programmed Cell Death 1 Receptor / analysis
  • Skin Neoplasms / enzymology
  • Skin Neoplasms / genetics*
  • Skin Neoplasms / immunology
  • Skin Neoplasms / pathology
  • T-Lymphocytes, Helper-Inducer* / enzymology
  • T-Lymphocytes, Helper-Inducer* / immunology
  • T-Lymphocytes, Helper-Inducer* / pathology
  • rhoA GTP-Binding Protein / genetics*

Substances

  • Biomarkers, Tumor
  • CXCL13 protein, human
  • Chemokine CXCL13
  • ICOS protein, human
  • Inducible T-Cell Co-Stimulator Protein
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • RHOA protein, human
  • IDH2 protein, human
  • Isocitrate Dehydrogenase
  • Neprilysin
  • rhoA GTP-Binding Protein