Analysis of clonality in cutaneous B‐cell lymphoma and B‐cell pseudolymphoma using skin flow cytometry: Comparison of immunophenotyping and gene rearrangement studies. Issue 2 (14th July 2021)

• Record Type: Journal Article
• Authors: Nakagawa, Yuki; Hamada, Toshihisa; Takahashi, Takahide; Miyake, Tomoko; Hirai, Yoji; Iwatsuki, Keiji; Morizane¹, Shin
• Other Names: Kawai Kazuhiro guestEditor.
• Is Part Of: Journal of dermatology. Volume 49:Issue 2(2022)
• Page Start: 246
• Page End: 252
• Publication Date: 2021-07-14
• Subjects: B‐cell lymphoma -- gene rearrangement -- light‐chain restriction -- pseudolymphoma -- skin FCM; Dermatology -- Periodicals; Dermatology -- Japan -- Periodicals; Skin -- Diseases -- Periodicals; 616.5005
• DOI: 10.1111/1346-8138.16057
• Languages: English
• ISSNs: 0385-2407

Abstract

Abstract: To identify clonal neoplastic cells in skin affected by B‐cell lymphoma using skin flow cytometry (FCM) techniques, we investigated light‐chain restriction using skin FCM with clonality assessed by polymerase chain reaction and light‐chain restriction by in situ hybridization (ISH). We retrospectively analyzed 16 cases of B‐cell lymphoma with cutaneous involvement: primary cutaneous diffuse large B‐cell lymphoma, leg type (pcDLBCL‐LT) (n = 7), DLBCL–not otherwise specified (DLBCL‐NOS) (n = 6), primary cutaneous follicle center lymphoma (pcFCL) (n = 1), and follicular lymphoma (n = 2), as well as cutaneous B‐cell pseudolymphoma (n = 9). Results of skin FCM light‐chain restriction analyses were compared with immunoglobulin H ( IgH ) gene rearrangement and κ/λ ISH findings. Skin FCM detected light‐chain restriction in 11 of 14 B‐cell lymphoma patients but none of the B‐cell pseudolymphoma patients. The sensitivity of skin FCM for distinguishing B‐cell lymphoma and B‐cell pseudolymphoma was 79%, and the specificity was 100%. Eleven of 13 B‐cell lymphoma patients exhibited gene rearrangement (sensitivity 85%), whereas six of seven pseudolymphoma patients were negative (specificity 86%). ISH was positive in three of 16 B‐cell lymphoma cases (sensitivity 19%) but none of the B‐cell pseudolymphoma cases (specificity 100%). ISH sensitivity was 29% for pcDLBCL‐LT, 17% for DLBCL‐NOS, and 0% for pcFCL and follicular lymphoma. Skin FCM therefore appears to be more sensitive than ISH in detecting light‐chain restriction in DLBCL and follicular lymphoma, and as sensitive as IgH gene rearrangement analysis in detecting clonality. Skin FCM is thus a promising diagnostic tool for identifying monoclonal neoplastic B‐cell populations.