OUTLINE: This is a dose escalation study. Patients receive oral fenretinide once daily on days 1, 8 and 9 and three times a day on days 2-7. Courses repeat every 3 weeks in the absence of disease progression or unacceptable toxicity. Treatment continues for up to 6 months following complete remission. Accessible tumors are biopsied on day 8. Cohorts of 3-6 patients receive escalating doses of fenretinide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose limiting toxicity.