Amifostine and Melphalan in Treating Patients With Primary Systemic Amyloidosis Who Are Undergoing Peripheral Stem Cell Transplantation

DISEASE CHARACTERISTICS: * Histologically confirmed amyloidosis * No secondary familial or localized amyloidosis * Presence of monoclonal protein by immunoelectrophoresis or immunofixation of serum or urine * No primary amyloidosis manifested only by carpal tunnel syndrome or purpura * Amyloid deposits in a plasmacytoma or in bone marrow vessels in an asymptomatic individual not considered an amyloid syndrome * Amyloid syndromes include any of the following: * Hepatomegaly * Cardiomyopathy * Nephrotic range proteinuria * Peripheral or autonomic neuropathy * No multiple myeloma defined by 1 of the following: * Presence of lytic bone disease * More than 30% bone marrow plasma cells PATIENT CHARACTERISTICS: Age * 18 to 70 Performance status * ECOG 0-1 Life expectancy * Not specified Hematopoietic * Platelet count at least 100,000/mm\^3 Hepatic * See Disease Characteristics * Total or direct bilirubin no greater than 2.0 mg/dL * Alkaline phosphatase no greater than 4 times upper limit of normal Renal * See Disease Characteristics * Creatinine less than 3.0 mg/dL Cardiovascular * See Disease Characteristics * Ejection fraction at least 45% by echocardiogram * No New York Heart Association class III or IV heart disease * Systolic blood pressure ≥ 90 mmHg Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No active infection * No other malignancy within the past 5 years except surgically treated carcinoma in situ of the cervix, nonmelanoma skin cancer, or indolent prostate cancer PRIOR CONCURRENT THERAPY: Biologic therapy * At least 4 weeks since prior interferon Chemotherapy * At least 4 weeks since prior melphalan * Lifetime total melphalan dose less than 150 mg/m\^2 (based on ideal body weight) Endocrine therapy * At least 4 weeks since prior dexamethasone Radiotherapy * No prior radiotherapy for amyloidosis Surgery * Not specified Other * No antihypertensive medications for at least 24 hours prior to, during, and for 1 hour after amifostine administration * No other prior treatment