Abstract:
Idiopathic inflammatory myositis (IIM) is an expanding field in rheumatology as more myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) become available for testing. Clinical signs and specific clinical phenotypes are found in the MSA group, with as high as 70% of IIM patients having a positive myositis-specific antibody. Although IIM remains a heterogenous disease, assigning a phenotype to these patients will prove to be critical as we learn which cases require more aggressive therapy and what complications to search for as the disease progresses. The IIM patients for the last 5 years were reviewed and profiled using recently available myositis profile testing at our National Health Laboratory Services. Patients from our rheumatology clinic were categorized according to this antibody profile. Three cases diagnosed with dermatomyositis (DM) were selected for discussion in this article which include a patient with each of the following: anti-transcriptional intermediary factor 1-y (TIF1y) DM, anti-melanoma differentiation-associated protein 5 (MDA 5) DM, and anti-signal recognition particle (SRP) DM.
