A case of mycosis fungoides concurrent with lymphomatoid papulosis

Mycosis fungoides (MF) is the most frequent cutaneous T cell lymphoma (CTCL). Since the major tumor cell of MF is the helper T cell, positive markers are usually CD3, CD4 and CD45RO. Some MFs show CD30 positivity and the major differential diagnosis for MF with CD30 positivity includes transformed MF and MF concurrent with primary cutaneous anaplastic large cell lymphoma and lymphomatoid papulosis. As each disease shows a different prognosis, an exact diagnosis is crucial for proper treatment. We now report a case of 44-year-old male patient with mycosis fungoides which developed several papules on preexisting MF patches. On biopsy of the newly formed papules, CD 30 positive cells were observed and the histologic features were consistent with lymphomatoid papulosis. Both the lesions of lymphomatoid papulosis and MF responded well to narrow band ultraviolet B phototherapy.