Seronegative dermatomyositis presenting with features of anti-MDA5 subtype

Polymyositis Presenting With Nontraumatic Rhabdomyolysis and Dysphagia: A Case Report

Idiopathic inflammatory myopathies (IIMs) are a rare, heterogeneous group of diseases with a characteristic clinical presentation consisting of muscle inflammation and weakness. They often present with accompanying extra-muscular findings, most notably in the skin, lungs, and joints. Inflammatory myopathies are also identified by their characteristic laboratory abnormalities, including a 10- to 50-fold increase in creatinine kinase, elevated liver enzymes, and characteristic electromyography and magnetic resonance imaging findings. Distinct autoimmune markers and clinical phenotypes have advanced our understanding of IIMs and have led to the recognition of 5 distinct entities, each with its unique pathophysiology, autoimmune markers, and clinical features. While autoimmune panels and muscle biopsies help clinicians distinguish one entity from the other, their sensitivity and specificity vary. Of the various inflammatory myopathies, polymyositis remains the most elusive. Often, the diagnosis is ultimately made by combining clinical findings and laboratory data. As our case report illustrates, clinicians must use this constellation of data to initiate treatment for suspected polymyositis despite negative autoimmune panels and negative muscle biopsy.

Clinical and histopathological features of adult patients with dermatomyositis and MDA5 autoantibody seropositivity status, as determined by commercial-based testing: A retrospective, single-institution comparative cohort study

BACKGROUND

Although MDA-5 autoantibodies are widely explored in dermatomyositis (DM), most studies relied on MDA-5 autoantibody testing performed in research settings and not with the now-available commercial laboratory tests.

OBJECTIVE

To characterize the clinical and histopathologic data in patients with DM and circulating MDA5-autoantibodies, as defined by commercial-based testing.

METHODS

Retrospective review of patients with DM who underwent MDA-5 antibody testing. All available skin biopsy slides were reviewed.

RESULTS

Cutaneous features more prevalent in MDA-5 positive DM included Raynaud syndrome (p <0.0001), cutaneous ulcerations (p=0.013), mechanic hands (p=0.0164), palmar papules (p=0.004), oral ulcers (p=0.024) and alopecia (p= 0.027). Joint and pulmonary involvement were more frequently in patients with MDA-5 positive DM (both p<0.0001) as was dysphagia (p=0.0029). Myopathy (p=0.404) and malignancy (p=0.342) were not statistically different between the cohorts. Vasculopathy was more frequent in MDA-5 positive DM (p=0.005), while spongiosis was less (p=0.016).

CONCLUSIONS

This study not only confirmed some known associations between disease manifestations and MDA-5 autoantibody status, as determined by commercially-available testing, but also identified new associations, including Raynaud syndrome and dysphagia.

Cricopharyngeal bar and dermatomyositis: A cause of rapidly progressive dysphagia

BACKGROUND

Idiopathic inflammatory myopathies (IIM) are immune-mediated conditions that affect striated muscle, and are frequently associated with dysphagia. Dysphagia in these cases can be due to weakness of the muscles involved in swallowing or the presence of restrictive pharyngeal defects, such as cricopharyngeal bars. Treatment of dysphagia in IIM revolves around immunosuppressive therapies, and procedures to disrupt cricopharyngeus muscle when immunosuppressive therapies are unsuccessful.

CASE REPORT

A 73-year-old female presented with rapidly progressive proximal muscle weakness and dysphagia to the point she could not swallow liquids or solids. She had a rash over the extensor surfaces of the limbs, and periorbital-edema. Her creatine kinase was elevated, and skin biopsy showed an interface inflammatory reaction; however, myositis line assay revealed no autoantibodies, and a muscle biopsy was unremarkable. She was diagnosed with dermatomyositis with life-threatening dysphagia, and was admitted to our institution and treated with corticosteroids, methotrexate and intravenous immunoglobulin. A videofluoroscopic swallowing study revealed a large esophageal protrusion at the level of C5-C6, which was thought to be consistent with a cricopharyngeal bar, with large boluses unable to pass, leading to aspiration. After 10 weeks of treatment, the cricopharyngeal bar remained present, but swallowing had improved to the point that she was successfully swallowing all consistencies.

CONCLUSION

Dysphagia associated with IIM can be multifactorial, and can be due to the involvement of the muscles of swallowing in the inflammatory process, or due to restrictive pharyngeal defects, and determination of the cause of dysphagia can assist with management.