Patients with advanced MF or SS who are between 18 and 70 years of age and have a matched family donor 18 years of age or older may be eligible for this study. Candidates will have a medical history, physical examination and blood tests, lung and heart function tests, X-rays of the chest, eye examination, and bone marrow sampling (withdrawal through a needle of about a tablespoon of marrow from the hip bone), and small skin biopsy (surgical removal of a piece of tissue for microscopic examination) or needle biopsy of the tumor.