Temozolomide in Treating Patients With Mycosis Fungoides or Sezary Syndrome

DISEASE CHARACTERISTICS: Histologically confirmed mycosis fungoides or Sezary syndrome Stage IB-IVB disease Must have failed at least one prior systemic therapy Generalized erythroderma allowed Measurable disease and at least one indicator lesion OR evaluable disease for erythrodermic patients only Prior radiotherapy to areas of measurable disease allowed if disease progression is present in the site or if measurable disease is present outside irradiation port PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 OR WHO 0-2 Life expectancy: At least 3 months Hematopoietic: WBC at least 3,000/mm^3 Absolute granulocyte count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hepatic: Bilirubin no greater than 2.2 mg/dL SGOT or SGPT no greater than 2 times upper limit of normal (ULN) Alkaline phosphatase no greater than 2 times ULN Renal: Creatinine no greater than 2.0 mg/dL Cardiovascular: No New York Heart Association class III or IV heart disease No clinically significant peripheral venous insufficiency Other: HIV negative No poorly controlled diabetes mellitus No acute infection requiring IV antibiotics No other medical condition that would prevent ingestion or absorption of oral medication No other neoplasm within the past 5 years except curatively treated squamous cell or basal cell skin cancer, melanoma in situ, or carcinoma in situ of the cervix Not pregnant or nursing Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy and recovered No concurrent growth factors or epoetin alfa Chemotherapy: At least 4 weeks since prior chemotherapy and recovered Endocrine therapy: At least 4 weeks since prior topical steroids Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy for local control or palliation and recovered Surgery: Recovered from prior major surgery Other: No other concurrent investigational drugs