A Multiple Myeloma (MM), IgG-lambda stage III-A was diagnosed in a 41-year-old-man. After VAD cycles IgG decreased from 7.5 to 2.4 g/dL. were mobilized with cyclophosphamide and 10 µg/Kg G-CSF. Three days after the collection of peripheral stem cell, the patient had fever, nausea, vomiting, liquid stools, shoulder and knee arthralgia and dehydration. Upper GI endoscopy showed esophageal candidiasis and ulcerative necrotic lesions both in stomach and duodenum; the biopsy confirmed necrosis. Simultaneously, the appearance of purpura with maculopapular lesions of diverse sizes appeared in the feet progressing to the limbs and trunk. Hematuria and proteinuria were also observed. Skin biopsy showed leukocytoclastic vasculitis. Renal biopsy showed focal and segmental glomerulonephritis. Serum ANCA, cryoglobulins, anti-HCV and RF were negative, and serum monoclonal IgG was 1290 mg/dL. Daily treatment with iv methylprednisolone pulses for 3 days improved skin lesions and digestive involvement. Macroscopic hematuria and proteinuria improved after two months of steroid treatment (Rev Méd Chile 2000; 128: 1255-60)