title: Systemic Immunoglobulin Light Chain Amyloidosis-Associated Myopathy: Presentation, Diagnostic Pitfalls, and Outcome.
abstract: OBJECTIVE
  To characterize the natural history of immunoglobulin light chain amyloidosis-associated myopathy and to provide guidelines for recognition.
  
  
  METHODS
  Fifty-one patients with systemic immunoglobulin light chain amyloidosis and biopsy-confirmed muscle amyloid deposition diagnosed between January 1, 1995, and December 31, 2015, were included in this study.
  
  
  RESULTS
  Common presenting symptoms were muscle weakness in 49 patients (96%), dysphagia in 23 (45%), myalgia in 17 (33%), macroglossia in 17 (33%), jaw claudication in 13 (25%), and hoarseness in 9 (18%). The median time from the onset of symptoms to diagnosis was almost 2 years. Less than two-thirds of the patients with an outside muscle biopsy (16 of 27) had an established pathologic confirmation of amyloidosis due to failure to routinely incorporate Congo red staining. Moreover, 12 patients were incorrectly treated before diagnosis of amyloid myopathy. More than half of the patients had normal creatine kinase levels at diagnosis. Cardiac troponin T levels were elevated above the reference range in 5 of 12 patients who lacked evidence of cardiac involvement. Median overall survival was 32 months. Factors associated with inferior survival were involvement of more than 2 organs (median survival, 13 months), cardiac involvement (median survival, 15 months), and absence of stem cell transplant (median survival, 18 months). With the exclusion of patients treated with stem cell transplant, no improvement in survival was seen over the 1995-2004 and 2005-2015 decades.
  
  
  CONCLUSIONS
  Immunoglobulin light chain amyloidosis-associated myopathy is rare. Delay in diagnosis is common, and there is a high rate of pathologic and clinical misdiagnosis. Awareness of elevation of cardiac troponin T levels in the absence of cardiac disease may be a clue to diagnosis.
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Eli
authors.initials: E
authors.lastname: Muchtar
authors.affiliation: Department of Haematology, Businco Hospital, Cagliari, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Derudas
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN.
authors.forename: Michelle
authors.initials: M
authors.lastname: Mauermann
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN.
authors.forename: Teerin
authors.initials: T
authors.lastname: Liewluck
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Angela
authors.initials: A
authors.lastname: Dispenzieri
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Shaji K
authors.initials: SK
authors.lastname: Kumar
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: David
authors.initials: D
authors.lastname: Dingli
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Martha Q
authors.initials: MQ
authors.lastname: Lacy
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Francis K
authors.initials: FK
authors.lastname: Buadi
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: Hayman
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Prashant
authors.initials: P
authors.lastname: Kapoor
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN; Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
authors.forename: Nelson
authors.initials: N
authors.lastname: Leung
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN; Hospitalist Services, Essentia Health-St. Joseph's Medical Center, Brainerd, MN.
authors.forename: Rajshekhar
authors.initials: R
authors.lastname: Chakraborty
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Wilson
authors.initials: W
authors.lastname: Gonsalves
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Stephen
authors.initials: S
authors.lastname: Russell
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: John A
authors.initials: JA
authors.lastname: Lust
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Go
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Steven
authors.initials: S
authors.lastname: Zeldenrust
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kyle
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN.
authors.forename: S Vincent
authors.initials: SV
authors.lastname: Rajkumar
authors.affiliation: Division of Hematology, Mayo Clinic, Rochester, MN. Electronic address: gertz.morie@mayo.edu.
authors.forename: Morie A
authors.initials: MA
authors.lastname: Gertz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000505:Alopecia / Q000209:etiology; D000682:Amyloid / Q000378:metabolism; D000686:Amyloidosis / Q000097:blood / Q000175:diagnosis* / Q000401:mortality; D001706:Biopsy; D003402:Creatine Kinase / Q000097:blood; D003680:Deglutition Disorders / Q000209:etiology; D057210:Delayed Diagnosis; D003951:Diagnostic Errors; D005260:Female; D006685:Hoarseness / Q000209:etiology; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008260:Macroglossia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009135:Muscular Diseases / Q000209:etiology*; D063806:Myalgia / Q000209:etiology; D020107:Troponin T / Q000097:blood
chemical_list: D000682:Amyloid; D007147:Immunoglobulin Light Chains; D020107:Troponin T; D003402:Creatine Kinase