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