Detection of immunoglobulin light-chain restriction in cutaneous B-cell lymphomas by ultrasensitive bright-field mRNA in situ hybridization

• Published in: Journal of cutaneous pathology Vol. 42; no. 2; pp. 82 - 89
• Main Authors: Minca, Eugen C, Wang, Hongwei, Wang, Zhen, Lanigan, Christopher, Billings, Steven D, Luo, Yuling, Tubbs, Raymond R, Ma, Xiao-Jun
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2015
• Subjects: B-Lymphocytes - pathology; cutaneous; Flow Cytometry; Humans; Immunoglobulin kappa-Chains - genetics; Immunoglobulin lambda-Chains - genetics; Immunoglobulin Light Chains - genetics; Immunohistochemistry - methods; in situ hybridization; In Situ Hybridization - methods; kappa/lambda; lymphoma; Lymphoma, B-Cell - diagnosis; Lymphoma, B-Cell - immunology; Lymphoma, B-Cell - metabolism; Lymphoma, B-Cell - pathology; RNA, Messenger - analysis; RNA, Messenger - metabolism; skin; Skin Neoplasms - diagnosis; Skin Neoplasms - immunology; Skin Neoplasms - pathology; cutaneous; skin; kappa/lambda; lymphoma; in situ hybridization
• ISSN: 0303-6987; 1600-0560
• DOI: 10.1111/cup.12415

Background Detection of immunoglobulin light‐chain restriction is important in the diagnosis of B‐cell non‐Hodgkin lymphoma (B‐NHL). Flow‐cytometry, commonly used to evaluate light‐chain restriction, is impractical to be used in cutaneous specimens. Immunohistochemical and conventional chromogenic in situ hybridization (CISH) methods on formalin‐fixed‐paraffin‐embedded (FFPE) tissue lack sufficient sensitivity to detect low‐level light‐chain expression in B‐NHL without plasmacytic differentiation. Ultrasensitive bright‐field mRNA‐ISH (BRISH) for in situ light‐chain detection in cutaneous B‐NHL has been assessed. Design Kappa/lambda mRNA was detected using two‐color BRISH (RNAscope 2xPlex, Advanced Cell Diagnostics) on 27 FFPE skin biopsies and excisions from patients with available B‐cell PCR clonality studies: 16 clonal B‐cell lesions (6 follicle center lymphoma, 5 marginal zone lymphoma, 3 large B‐cell lymphoma, and 2 other) and 11 non‐clonal B‐cell proliferations. Results BRISH was successful in 15/16 clonal B‐cell lesions and 11/11 non‐clonal proliferations. Light‐chain restriction was detected in 15/15 clonal lesions and in 1/11 non‐clonal proliferations (96.1% overall concordance with clonality PCR). In 4/5 marginal zone lymphomas, light‐chain restriction was detected as strong monotypic mRNA expression in a B‐cell subset, consistent with plasmacytic differentiation. Conclusion Ultrasensitive BRISH can successfully detect light‐chain restriction in B‐NHL from FFPE skin specimens and may be a useful adjunct ancillary tool in cases not resolved by CISH or immunohistochemical methods.