Tretinoin in Treating Patients With Mycosis Fungoides or Sezary Syndrome

DISEASE CHARACTERISTICS: Biopsy-proven mycosis fungoides/Sezary syndrome Stage I-IV disease No CNS involvement At least 1 measurable lesion required (skin, lymph nodes, visceral lesion, or peripheral blood counts) PATIENT CHARACTERISTICS: Age: Over 18 Performance status: ECOG 0-3 Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 75,000/mm3 Hepatic: Bilirubin no more than 2.0 mg/dL Transaminases no more than 2 x normal Alkaline phosphatase no more than 2 x normal Renal: Creatinine no more than 2.0 mg/dL Other: No active systemic infection No significant organ failure uncontrolled with medication No pregnant or lactating women Effective contraception required of fertile women PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior systemic therapy Chemotherapy: At least 4 weeks since prior topical chemotherapeutics or systemic therapy Endocrine therapy: At least 4 weeks since prior topical (including steroid) therapy or systemic therapy Radiotherapy: Not specified Surgery: Not specified