Mycosis fungoides is characterized by which type of neoplastic cells?

Mycosis fungoides is a cutaneous T-cell lymphoma primarily characterized by malignant transformation of skin-homing T-cells, particularly CD4+ T-helper lymphocytes. These atypical T-cells infiltrate the skin, leading to clinical manifestations that begin with patches and plaques, and can evolve into more advanced and invasive skin lesions over time.

The involvement of skin-homing T-cells is crucial as these cells possess specific adhesion molecules and chemokine receptors that direct them to the skin. The neoplastic process in mycosis fungoides leads to the accumulation of these abnormal T-cells in the epidermis and dermis, contributing to the disease’s unique pathology.

Alongside the neoplastic T-cells, this condition can also progress to the development of a leukemic phase known as Sézary syndrome in its advanced form, where atypical T-cells circulate in the blood and can affect the lymph nodes and other organs. The characterization of mycosis fungoides relies heavily on the identification of these malignantly transformed skin-homing T-cells through histopathological examination.