Data from the Mayo Clinic, Rochester, Minn., suggest that about 20% of dermatomyositis patients have clinically amyopathic disease, and most (76%) of these cases are in women (Arch. Dermatol. 2010;146:26-30).
"The take-home point here is that these skin-limited patients are much harder to diagnose than the ones who come in with the classic muscle weakness, because the rash can be subtle," Dr. Vleugels said, noting that the diagnosis must be made clinically, because there is no confirmatory test.
She described a dermatomyositis patient who had experienced a rash for more than 2 years, and who was referred for lupus – even a biopsy was read as lupus.
"We need to say, ‘Oh, that could also be dermatomyositis,’" she said, adding: "If you see a patient with skin-limited disease, you’re still going to screen them for pulmonary disease, and you’re still going to screen them for cancer."