Eye of the Beholder

Posted by • May 6th, 2016

73Dermatomyositis, polymyositis, and necrotizing autoimmune myopathy all cause proximal muscle weakness. Proximal weakness is often progressive, with patients reporting difficulty in raising their arms above their head, climbing stairs, or standing from a seated position. Clinically, dermatomyositis is distinguished from polymyositis and necrotizing autoimmune myopathy by its distinctive dermal findings.

A 47-year-old man presented to an urgent care ambulatory clinic with a 3-day history of swelling around his left eye and a sensation of tightness in his throat. It had become difficult for him to swallow solids, and he felt as though food was sticking in his throat. A new Clinical Problem-Solving summarizes.

Clinical Pearl

• What are the characteristic dermal findings associated with dermatomyositis?

Dermatomyositis is distinguished from polymyositis and necrotizing autoimmune myopathy by its distinctive dermal findings, including Gottron’s papules (violaceous papules on the dorsum of the metacarpalphalangeal and interphalangeal joints), Gottron’s sign (nonpalpable macules over the extensor surfaces of joints), heliotrope rash (a violaceous rash involving the periorbital skin), V sign (also known as shawl sign), in which there are macular erythematous lesions over the anterior chest and back, and holster sign, in which these lesions appear over the upper lateral thighs. Patients may have dilated nail-fold capillaries (which can be visualized with a dermatoscope) and ragged or thickened cuticles. In rare instances, the characteristic cutaneous features of dermatomyositis develop without muscle involvement, in a condition that is designated amyopathic dermatomyositis or dermatomyositis sine myositis.

Clinical Pearl

• What laboratory findings may be seen in dermatomyositis?

Elevation in creatine kinase levels is characteristic of all the inflammatory myopathies, with levels rising up to 50 times as high as the upper limit of the normal range in patients with dermatomyositis. Myositis-specific antibodies are often measured, since findings can have prognostic significance. The most common such antibody is anti–Jo-1, which is present in up to 20% of patients with polymyositis or dermatomyositis. The anti–Jo-1 antibody is associated with the antisynthetase syndrome, a constellation of arthritis, Raynaud’s phenomenon, mechanic’s hands (in which there is cracking along the distal tip and edges of the fingers), and interstitial lung disease, which is associated with a poorer prognosis in patients with an inflammatory myopathy.

Morning Report Questions

Q: What is the nature of the cancer risk in patients with dermatomyositis? 

A: A reported 15 to 25% of patients with dermatomyositis have had prior cancer or have concurrent cancer, or cancer will develop in them. However, there does not appear to be a correlation between dermatomyositis and a particular type of cancer; in most patients, the diagnosis of dermatomyositis comes after the diagnosis of cancer. There are no consensus guidelines for cancer screening in patients with inflammatory myositis. It is prudent to ensure age-appropriate cancer screening; some experts recommend chest, abdominal, and pelvic imaging for further assessment in patients without a known cancer, although data are lacking in regard to the associated cost-effectiveness and outcomes. Anti–transcriptional intermediary factor 1γ (also referred to as anti-p155) and anti–nuclear matrix protein 2 are associated with an increased risk of cancer in adults with dermatomyositis; the former, which is included in the myositis-specific antibody panel at most laboratories, has been reported to have a positive predictive value of 78% and a specificity of 89%.

Q: What medications are used for the initial treatment of dermatomyositis? 

A: Although there is a paucity of controlled trials on the treatment of dermatomyositis, glucocorticoids are the mainstay of treatment for dermatomyositis, polymyositis, and autoimmune necrotizing myositis — largely on the basis of clinical experience. Oral prednisone is often started at a dose of 0.75 to 1 mg per kilogram of body weight, with intravenous glucocorticoids reserved for severe or progressive cases; doses are tapered gradually, primarily on the basis of the patient’s symptoms. Additional immunosuppressants are often added as glucocorticoid-sparing agents — most often methotrexate or azathioprine, although mycophenolate and cyclosporine have also been used.

2 Responses to “Eye of the Beholder”

  1. Ichizo Nishino says:

    I think that the frequency of anti-Jo-1 antibody, 20% in DM and PM, is too high if anti-synthetase syndrome and necrotizing myopathy are classified as distinct subtypes of IIM as suggested by recent ENMC workshop report.

  2. Mirian Abila says:

    Nice site. Lymphoma Prognosis is frightening but there are ways to help prevent this unpleasant disease altogether. Be careful.