Facing Uncertainty

Dermatomyositis and Crohn's disease - Case report

Immune-mediated diseases tend to overlap in ways that are not completely understood. When a presentation is not entirely explained by a former condition, other hypotheses should arise. Additionally, the activity of 2 overlapping immune-mediated conditions is not always associated. We present an unusual association between Crohn's disease and dermatomyositis in a 28-year-old man. The patient presented with a 2-month history of proximal muscle weakness and a skin rash with heliotrope periorbital edema. Since the patient had already been diagnosed with Crohn's disease, he was under immunosuppressive therapy, and he had a family history of psoriasis, the diagnosis was not immediate and required an integrative approach. Laboratory analysis revealed elevated creatine kinase, aldolase, lactic dehydrogenase and transaminase levels. He had no symptoms of Crohn's disease exacerbation. Magnetic resonance imaging, electromyography, and muscle biopsy findings were consistent with inflammatory myopathy, although non-specific. Corticosteroids were initiated with clinical and laboratory improvement within 1 month.

Dermatomyositis autoantibodies: how can we maximize utility?

The past 15 years has seen significant advances in the characterization of myositis-specific autoantibodies (MSAs) and their associated phenotypes in patients with dermatomyositis (DM). As more careful studies are performed, it is clear that unique combinations of clinical and pathological phenotypes are associated with each MSA, despite the fact that there is considerable heterogeneity within antibody classes as well as overlap across the groups. Because risk for interstitial lung disease (ILD), internal malignancy, adverse disease trajectory, and, potentially response to therapy differ by DM MSA group, a deeper understanding of MSAs and validation and standardization of assays used for detection are critical for optimizing diagnosis and treatment. Like any test, the diagnostic sensitivity and specificity of assays for various MSAs is not perfect. Currently tests for MSAs are helpful at minimum for a clinician to assess relative risk or contribute to diagnosis and perhaps counsel the appropriate patient about what to expect. With international standardization and larger studies it is likely that more antibody tests will make their way into formal schemata for diagnosis and actionable risk assessment in DM. In this review, we summarize key considerations for interpreting the clinical and pathologic associations with MSA in DM and identify critical gaps in knowledge and practice that will maximize their clinical utility and utility for understanding disease pathogenesis.