Primary cutaneous follicular helper T-cell lymphoma.

Follicular helper T-cells (TFH) represent a specific subset of CD4-positive helper T-cells that help B-cells to differentiate into long-lived antibody-secreting plasma cells or memory B-cells. The expression of TFH markers in neoplastic T-cells, traditionally related to the angioimmunoblastic (AITL) subgroup of peripheral T-cell lymphomas, is nowadays well-known to be more widespread than previously thought. We report hereby a case of cutaneous T-cell lymphoma in a 75-year-old woman, whose morphological and immunophenotypical features raises the differential diagnosis between cutaneous involvement by AITL and the recently described primary cutaneous T-cell lymphoma with follicular helper-phenotype.