Dermatopathic reaction of lymph nodes in HTLV‐1 carriers: a spectrum of reactive and neoplastic lesions

AIMS: Dermatopathic reaction is a histopathological finding of lymph nodes that usually occurs in patients with inflammatory pruritic cutaneous lesions. However, it is sometimes seen in patients with cutaneous T cell lymphoma. Adult T cell leukaemia/lymphoma (ATLL) is a T cell malignancy caused by infection with human T cell leukaemia virus type I (HTLV‐1), which is frequently accompanied by cutaneous lesions. However, the detailed clinicopathological characteristics of the dermatopathic reaction of lymph nodes in ATLL patients and HTLV‐1 carriers, addressed in this study, remains to be clarified. METHODS AND RESULTS: We retrospectively analysed 18 nodal lesions with dermatopathic reaction in HTLV‐1 carriers. Axillary and inguinal lymph nodes were the primary affected tissues. Three cases with atypical lymphoid cell infiltration were defined as ATLL with dermatopathic reaction (ATLL‐D), showing an abnormal T cell immunophenotype and T cell monoclonality. Two of the three ATLL‐D patients died 14 and 7 months after diagnosis (the third case had a very short follow‐up). The other 15 patients were indistinguishable from reactive lesions and were defined as HTLV‐1‐associated lymphadenitis with dermatopathic reaction (HAL‐D). They showed an indolent clinical course, with only one case eventually transforming to aggressive disease. CONCLUSIONS: Lymph node lesions accompanied by dermatopathic reaction in HTLV1 carriers represent a spectrum that includes reactive and neoplastic conditions. HAL‐D should be distinguished from ATLL‐D, especially to avoid overtreatment.