LAUSR

Eruption of lymphocyte recovery (ELR) may occur during bone marrow aplasia after chemotherapies. We reviewed the clinical and pathologic features of 12 patients (male-female ratio, 7:5; median age, 61 years) with an atypical ELR histologically mimicking a primary cutaneous T-cell lymphoma such as Sézary syndrome or CD30+ T-cell lymphoproliferative disorder. All the patients displayed an erythematous maculopapular eruption on the trunk and the limbs associated with fever. All but one had received a polychemotherapy for an acute myeloid leukemia (n=10) or a urothelial carcinoma (n=1) before the occurrence of the skin eruption. One had an autoimmune lymphoproliferative syndrome causing chronic agranulocytosis requiring granulocyte colony-stimulating factor injection. In all patients, the skin eruption was associated with a slight increase of white blood cell count followed by bone marrow recovery within the next weeks. All skin biopsies showed a dermal perivascular lymphocytic infiltrate containing atypical medium- to large-sized CD3+, CD4+ and CD8+, CD25+, ICOS+, PD1- lymphocytes with a strong CD30 expression in most instances (n=10), suggesting the recruitment of strongly activated T cells in the skin. In 6 patients, a diagnosis of CD30+ lymphoproliferative disorder or Sézary syndrome was proposed or suspected histopathologically, and only the clinical context allowed the diagnosis of ELR with a peculiar presentation with atypical lymphocytes. We describe a series of patients with an unusual form of ELR characterized by the presence of atypical activated T cells in the skin. On a practical ground, pathologists should be aware of this distinctive and misleading presentation.