Abstract: A female patient developed cutaneous true histiocytic lymphoma at the age of 57. The main clinical manifestation was mono-morphous cutaneous nodules. Initially her general condition was good. Physical and laboratory examinations showed no abnormalily. Histopathologically uniform tumor cells diffusely infiltrated among the collagen bundles throughout the whole dermis of cutaneous nodules and were proved to be atypical histiocytes enzymically, immunologically and ultrastructurally and were further confirmed by tissue culture. The tumor cell line has been established in vitro(details in other paper). The COP regime for treatment had no effect while marked effect was obtained by adding CCNU. On account of leukopenia skin lesions recurred after with drawing of this drug. The patient died from cachexia. The whole course was one year and eight months.