Chronic dermatitis evolving to mycosis fungoides: report of four cases and review of the literature.

In four patients with long-standing chronic dermatitis, evolution into cutaneous T-cell lymphoma was observed. Two patients were men and two were women; they were aged forty-nine to sixty-five years at first presentation. Duration of dermatitis at admission was from two months to fifteen years, with the clinical and histologic diagnosis documented on initial examination. After another five to nine years, clinically and histologically verified mycosis fungoides occurred. In two patients, contact factors were verified as causative by results of patch testing; sensitivities documented included nickel, potassium dichromate, and formaldehyde. In a third patient, contact factors were implicated as causes, but patch testing was not performed. We propose that certain instances of cutaneous T-cell lymphoma may be caused by chronic antigenic immunostimulation with resultant malignant lymphocyte clonality.