Systemic amyloidosis: unusual presentation mistaken for a recurrent scabies infection.

We report the case of a 63-year-old woman with a history of undifferentiated connective-tissue disease, polyarthritis, and bilateral carpal tunnel syndrome who presented with generalized pruritus and erythematous and excoriated papules on the trunk and extremities. Empiric scabies treatment was unsuccessful. Patch testing and T-cell receptor gene rearrangement studies were unremarkable. The patient was found to have mild interstitial lung disease and hypogammaglobulinemia. Eventually a diagnosis of primary systemic amyloidosis was made after she developed frank lingual hypertrophy despite normal initial serum protein electrophoresis and negative abdominal fat pad aspiration. Diagnosis was confirmed with lingual biopsy. This case demonstrates an unusual presentation of primary systemic amyloidosis consisting of arthritis and intense debilitating pruritus without primary skin lesions for a full year prior to diagnosis of multiple myeloma. The patient responded to treatment with chemotherapy and corticosteroids.