AMYLOID MYOPATHY: AN INTRIGUING DIAGNOSIS

Abstract Immunoglobulin light chain (AL) amyloidosis is a plasma cell dyscrasia characterized by the deposition of misfolded monoclonal light chains in tissues which interferes with organ function. Despite the insoluble protein deposits can occur in any organ, skeletal muscle tissue is rarely affected. Herein we describe two patients in their seventies who presented muscle involvement in systemic AL amyloidosis. Clinical presentation and pathological features were different in the two patients and diagnosis was achieved by Congo red staining. This study highlights the importance of considering amyloid myopathy in the differential diagnosis of a primary disorder of muscle and the key role of Congo red staining that should be included in the pathological work-up of muscle biopsy in order to reach a timely and correct diagnosis and, consequently, begin an appropriate treatment for this potentially fatal disease.