a subset of patients with myositis have unique autoantibodies . this has informed and altered our approach to the diagnosis and management of the inflammatory myopathies .
the identification of myositis - specific autoantibodies ( msa ) and myositis - associated autoantibodies ( maa ) is important because they are associated with specific clinical phenotypes , and may guide the physician in terms of treatment planning .
this study reports the experience and clinical utility of the extended myositis antibody ( ema ) panel across a range of specialties in a large teaching hospital .
cork university hospital ( cuh ) is the largest university teaching hospital in ireland , and is a multi - specialty tertiary referral centre serving a population of 1.1 million .
we conducted a retrospective review of the electronic and paper records of all patients who had serum samples tested for msa and maa from april 2014 -mar 2015 .
euroline autoimmune inflammatory myopathies immunoblot was performed at university hospital galway . this assay uses membrane strip antigen testing to detect anti- : mi2 , tif1 gamma , mda3 , nxp2 , sae1 , ku , pm- scl 100 , pm - scl 75 , oj , ej , jo-1 , pl-7 , pl-12 , scl 70 , centromere a , centromere b , rna pol iii , fibrillarin , nor 90 , th / to , ku , pdgfr and ro-52 .
the use of additional investigations ( electromyography , mri , muscle biopsy , ct thorax ) and laboratory results , including creatine kinase and autoantibody profile , were documented .
we reviewed the utility of the assay in clarifying diagnosis , directing the investigative pathway and selecting the appropriate treatment .
twenty two patients ( mean age : 55 , sd:15 ) had an ema panel sent during the study period .
departments across the hospital included respiratory medicine ( n=8 , 36% ) , rheumatology ( n=5 , 23% ) , neurology ( n=4 , 18% ) , and other ( n=5 , 23% ) .
additional investigations performed depended on the clinical picture but included cardiac or musculoskeletal mri ( n=8 , 36% ) , ct thorax ( n=14,64 % ) , muscle biopsy ( n=7 , 32% ) and emg ( n=6 , 27% ) .
these autoantibodies were ana ( n= 10 , 45% ) , ena ( n=4 , 18% ) , anti - ro ( n=3 , 14% ) , anti - la ( n=1 , 5% ) , anti - dsdna ( n=1 , 5% ) and p- anca ( n=1 , 5% ) .
of the 17 patients who had a ck recorded , six ( 27% ) were elevated .
investigations and outcomes of patients with a positive ema panel are shown in table 2 .
patient 3 was a 35-year - old woman who presented in acute heart failure , nyha ii .
she had an elevated troponin ( 600s ) and ck ( 1787 ) , yet had a normal cardiac mri and transthoracic echocardiogram .
ema panel was positive for anti pm - scl 75 and anti pm - scl 100 antibodies , providing evidence that her cardiac failure was secondary to an autoimmune process .
her antibody profile resulted in first line treatment with rituximab , avoiding use of cyclophosphamide in a young woman who intended to start a family .
one - month post rituximab infusion her dyspnoea had resolved and both her ck and troponin levels had normalised .
patient 4 presented with a parietal stroke , and had a ck of 1539 on admission .
ema panel was positive for anti - pl7 , resulting in a diagnosis of anti - synthetase syndrome .
consequently , ct thorax and pulmonary function tests were performed , as well as onward referral to a respiratory physician .
treatment with a combination of rituximab and steroids has halted the progression of her dyspnoea , and has lead to a resolution of her weakness .
patient 6 tested positive for anti - tif1 gamma , and as a result has an annual ct - thorax abdomen and pelvis screening for an occult malignancy .
two were treated with steroids alone , three received steroids in combination with rituximab , and one received steroids followed by azathioprine and then mycophenylate mofetil .
ema panel is entering standard clinical practice but is not yet a routine tool in the investigation of idiopathic inflammatory myopathy ( iim ) in all centres .
diagnosis of autoimmune myopathy was previously dependent on muscle biopsy , emg and radiological investigations . with the advent of the ema panel
use of the panel avoided an invasive procedure ( muscle biopsy ) in two patients .
antibodies are detectable early in the disease course , and are specific for autoimmune myopathy the ema panel was diagnostic in 27% of patients , when traditional testing had not been definitive .
a positive ema panel is of significant clinical utility in facilitating decisions on appropriate investigations .
patient 6 in our study has entered a cancer surveillance programme after testing positive for anti - tif1 gamma ; an antibody associated with a significantly increased risk of malignancy . in anti - synthetase
patients 4 and 5 in our study had dyspnoea on presentation , and features of ild on imaging .
all patients diagnosed with anti - synthetase syndrome should have a high resolution ct thorax and pulmonary function tests performed .
onward referral to a respiratory physician , as was the case for patients 4 and 5 in our study , should be considered .
autoimmune myopathies are important to identify as they often respond to immunosuppression . in our study
all patients with a positive ema panel ( n=6 , 27% ) experienced symptomatic improvement on receiving immunosuppressants .
a positive panel in patient 3 provided evidence for use of rituximab , as opposed to cyclophosphamide .
in addition to myositis , a constellation of clinical features have been described in inflammatory myopathies , including dyspnoea , raynaud s phenomenon , polyarthritis , fever and weight loss .
ild may precede the occurrence of overt myositis in up to 20% of cases , and is estimated to result in an excess mortality of up to 50% .
the multisystem nature of autoimmune myopathy means patients need collaborative input from different medical specialities .
ongoing involvement of these physicians is particularly important ; all of whom need to be familiar with the diverse clinical presentation of iim .
this study illustrates the value of the ema panel in defining a heterogeneous patient population into clinicoserological phenotypes , thus guiding treatment pathways .
furthermore , it highlights the diversity of these presentations , the need for multi - speciality input and serves to heighten awareness among clinicians of the diagnostic use of extended myositis antibody testing in these cases .
 the discovery of unique autoantibodies has informed and altered our approach to the diagnosis and management of the inflammatory myopathies . 
 this study reports the initial clinical experience of use of the extended myositis antibody ( ema ) panel in the largest university teaching hospital in ireland . 
 we conducted a retrospective review of all patients who had serum samples tested for myositis specific antibodies and myositis associated antibodies from april 2014 to march 2015 . 
 a positive ema panel was of significant clinical utility in facilitating decisions on appropriate investigations , and need for onward referral to other physicians . 
 furthermore , this paper highlights the diversity of possible presentations of idiopathic inflammatory myopathy with subsequent need for multi - speciality involvement , and serves to heighten awareness among clinicians of the diagnostic use of extended myositis antibody testing in these cases . 