T‐cell receptor‐δ expression and γδ+ T‐cell infiltrates in primary cutaneous γδ T‐cell lymphoma and other cutaneous T‐cell lymphoproliferative disorders

• Published in: Histopathology 2018-10, Vol.73 (4), p.653-662
• Main Authors: Pulitzer, Melissa, Geller, Shamir, Kumar, Erica, Frosina, Denise, Moskowitz, Alison, Horwitz, Steven, Myskowski, Patricia, Kheterpal, Meenal, Chan, Alexander, Dogan, Ahmet, Jungbluth, Achim
• Format: Article
• Language: English
• Subjects: Adult; Antibodies, Monoclonal; CD30 antigen; classification; Female; Humans; immunohistochemistry; Immunohistochemistry - methods; immunological techniques; Immunoproliferative diseases; Lymphocytes; Lymphoma; Lymphoma, T-Cell, Cutaneous - diagnosis; lymphoproliferative disorders; Lymphoproliferative Disorders - diagnosis; Male; Monoclonal antibodies; Mycosis; Mycosis fungoides; Paraffin; Receptors, Antigen, T-Cell, gamma-delta - analysis; Skin; Skin Neoplasms - diagnosis; T cell receptors; T-cell lymphoma; Tumors
• ISSN: 0309-0167; 1365-2559
• DOI: 10.1111/his.13671

Aims The diagnosis of cutaneous γδ T‐cell lymphoma (GDTCL) requires the identification of γδ chains of the T‐cell receptor (TCR). Our aim in this study was, by using a new monoclonal antibody (mAb) against TCRδ, to evaluate TCRδ expression in formalin‐fixed paraffin‐embedded (FFPE) skin tissue from TCRγ+ cutaneous T‐cell lymphoma (CTCL), and to assess TCRδ expression within a spectrum of other cutaneous lymphoproliferative disorders (CLPDs). Methods and results Twelve cases (10 patients) with TCRγ+ CTCL and 132 additional CLPD cases (127 patients) were examined, including mycosis fungoides (MF) (n = 60), cutaneous GDTCL (n = 15), subcutaneous panniculitis‐like T‐cell lymphoma (SPTCL) (n = 11), and CD30+ lymphoproliferative disorder (LPD) (n = 24). Clone H‐41 against TCRδ was used on a Leica Bond‐3 automated stainer to label FFPE slides. H‐41 immunostaining was graded as percentage infiltrate: high (50–100%), moderate (10–49%), and low (0–9%). In TCRγ+ tumours, 12 of 12 (100%) patients showed TCRδ expression comparable to TCRγ expression. No (0%) TCRγ+ cases were negative for TCRδ. In all CLPDs, TCRδ expression was as follows: GDTCL, 16 of 20 cases (14 of 15 patients) high, two moderate, and two low; MF, 0 of 60 cases high, nine moderate, and 51 low; CD30+ LPD, one of 24 cases high, two moderate, and 21 low; and SPTCL, 0 of 11 cases (0 of 9 patients) high, two moderate, and two low. Three MF‐like cases and one SPTCL‐like case showed high expression; the remainder showed low expression. Conclusions mAb H‐41 against TCRδ matches TCRγ in immunostaining FFPE tissues from GDTCL, supporting H‐41 as a replacement for mAb γ3.20. TCRδ expression in our study suggests that the true occurrence of γδ+ non‐GDTCL CTCL/CLPD may be lower than suggested by the recent literature.