Cutaneous T cell lymphoma

In dermatology, cutaneous T cell lymphoma is "a group of lymphomas exhibiting clonal expansion of malignant T-lymphocytes arrested at varying stages of differentiation as well as malignant infiltration of the skin. Mycosis fungoides; Sezary syndrome; lymphomatoid papulosis; and primary cutaneous anaplastic lymphoma are the best characterized of these disorders."

These may sometimes evolve from pityriasis lichenoides.