Patients will stay in the hospital about 20 to 30 days after the transplant. After discharge, they will continue to take antibiotics, cyclosporine and mycophenolate mofetil at home. If the mastocytosis progresses, cyclosporine and mycophenolate mofetil will be tapered over 4 weeks. If the mastocytosis persists, patients may receive additional transfusions of donor lymphocytes to help kill the mast cells.