We describe a possibility of transformation of chronic dermatoses into malignant lymphomas of the skin. A possibility of transformation of large-plaque parapsoriasis into T-cell lymphoma is well known. Transformation of psoriasis into malignant lymphoma is less likely. A case of papular xanthomatosis preceding T-lymphoma of the skin is presented. A possibility of either co-existence of atopic dermatitis and lymphoma or transformation of atopic dermatitis into T-cell lymphoma is reported. We present our own case. Eighty-one years old patient, who is under medical care for atopic dermatitis since early childhood, was admitted after an episode of psycho-emotional stress. New rashes and increased itching were noted. An early stage of T-cell malignant lymphoma of the skin was diagnosed with histomorphologic testing (mycosis fungoides). In the second case onset of atopic dermatitis was noted at the age of 60 and was associated with psycho-emotional stress. She received treatment for following years as in- and outpatient. After injection of anti-flu vaccine, she noted significant condition worsening, increased itching, new rashes. An early stage of T-cell malignant lymphoma of the skin was diagnosed with histomorphologic testing (mycosis fungoides). In the cases, we presented, the age of transformation of atopic dermatitis into T-cell malignant lymphoma of the skin was above 60 years. In the first case, there was a typical course of atopic dermatitis with early childhood onset, and in the second, one atopic dermatitis developed in an adult patient. We can assume that psycho-emotional stress in one case and anti-flu vaccine in the second one preceded transformation of atopic dermatitis into T-cell malignant lymphoma of the skin.