Exclusion of cutaneous T-cell lymphoma (CTCL) by another dermatosis has not been reported. The mechanism for the epidermotropism of helper T lymphocytes in this indolent malignancy is not known. Although there is evidence that Langerhans cells (LC) play a role in the epidermotropism of lymphocytes in CTCL, clinical or in vivo support is lacking. We describe a patient with CTCL who developed herpes zoster involving the left T8 dermatome. When his CTCL became widespread after the herpes zoster healed, the previously affected areas of herpes zoster and their periphery were clinically free of lymphoma. Immunohistochemical analysis of a clinically uninvolved patch revealed absence of CD1a+ cells in the epidermis, consistent with loss of LC in the areas spared by CTCL. There was no loss of LC in areas affected by CTCL. This is an unusual inhibition of CTCL by a prior viral infection. The loss of LC in the clinically spared skin suggests a role for LC in the epidermotropism of lymphocytes in CTCL.