Cyclophosphamide in Treating Young Patients With Severe Autoimmune Enteropathy

DISEASE CHARACTERISTICS: * Diagnosis of severe autoimmune enteropathy * Condition is resistant to conventional therapy * Histologic evidence of severe villous atrophy with intense lymphocytic infiltrate of the lamina propria by small intestinal biopsy within the past 3 months * Disease failed to respond after ≥ 2 months of corticosteroid therapy at a dose of ≥ 0.5 mg/kg/day or ≥ 40 mg/day for patients \> 20 kg AND 1 of the following therapies: * Cyclosporine resulting in ≥ 1 whole blood level of \> 200 ng/mL * Tacrolimus resulting in ≥ 1 whole blood level of 5 ng/mL * At least 50% estimated caloric needs provided by parenteral nutrition * History of intractable diarrhea, defined as frequent watery stools for \> 3 months that does not respond to dietary restriction * No celiac disease, defined by a history of positive antiendomysial antibody or tissue transglutaminase antibody * No primary immunodeficiency or x-linked autoimmunity-allergy dysregulation PATIENT CHARACTERISTICS: Performance status * Lansky 60-100% Life expectancy * Not specified Hematopoietic * Not specified Hepatic * Not specified Renal * Not specified Cardiovascular * Ejection fraction ≥ 40% OR shortening fraction ≥ 20% Pulmonary * FVC or FEV\_1 ≥ 50% of predicted (for patients \> 8 years of age) * No clinically abnormal pulmonary function or abnormal pulse oximetry (for patients ≤ 8 years of age) Other * Not pregnant * Negative pregnancy test * Fertile patients must use effective contraception during and for at least 9 months after completion of study treatment * No known chromosomal abnormality PRIOR CONCURRENT THERAPY: Biologic therapy * No immunizations for at least 6 months after completion of study treatment Endocrine therapy * See Disease Characteristics * At least 5 days since prior corticosteroids * No concurrent dexamethasone as an anti-emetic Other * At least 5 days since other prior immunosuppressive medications (e.g., tacrolimus or cyclosporine)