Atypical manifestations of pityriasis lichenoides chronica: development into paraneoplasia and non-Hodgkin lymphomas of the skin.

Three patients with atypical courses and manifestations of pityriasis lichenoides chronica (PLC) are presented. The first patient is a 21-year-old white woman who showed a good response of her PLC lesions as well as her reactive oligoarthritis to repeated PUVA treatments combined with oral prednisone during 1 year. The effect of the treatment then decreased. The patient developed a low-grade malignant lymphoma of the lung. When the lymphoma of the lung improved after chemotherapy, the PLC eruptions improved, too. The second patient is a 41-year-old man, whose Hodgkin's disease stage IVa was successfully treated by chemotherapy and radiotherapy in 1984. In 1987 he showed PLC lesions which responded well to PUVA therapy, later also in combination with etretinate. Until 1988 repeated skin biopsies revealed a non-specific eczematous pattern. In 1989 the recalcitrant PLC eruptions finally revealed a pleomorphic non-Hodgkin lymphoma of the skin with medium-sized cells. The third patient had a PLC for about 9 years when Hodgkin's disease stage Ia was diagnosed. At the beginning the skin biopsy showed an eczematous pattern, but 2 years later, in 1990, skin infiltrations of a large-cell, anaplastic non-Hodgkin lymphoma were seen. These cases show that PLC in rare cases may either represent a paraneoplastic skin disease or may itself develop into cutaneous lymphomas.