Expression of T‐cell receptor‐γδ in normal human skin, inflammatory dermatoses and mycosis fungoides

BACKGROUND: T cells expressing the γδ T-cell receptor (TCR) (γδ T cells) are found in normal epithelial tissues such as the skin. However, the proportions of γδ T cells that may be observed in commonly encountered cutaneous diseases with a prominent lymphocytic infiltrate have not been elucidated. METHODS: Our pathology database was searched for cases of mycosis fungoides, erythema multiforme, graft-versus-host disease, lichen planus, lupus panniculitis and spongiotic dermatitis. Immunostaining for CD3, βF1 and the TCR γ chain was performed on formalin-fixed paraffin-embedded specimens retrieved from these cases to determine the normal range of γδ T cells in these diseases. RESULTS: In 100 of the 101 cases studied (99.0%), γδ T cells accounted for less than 10% of the T-cell infiltrate. Furthermore, γδ T cells were essentially absent in 74 cases (73.3%). CONCLUSIONS: These results suggest that γδ T cells very rarely account for more than 10% of the lymphocytic infiltrate in common inflammatory or infiltrative processes of the skin. Any case of suspected mycosis fungoides or interface dermatitis that possesses more than 10% γδ T cells should raise consideration for further investigation.