Novel scoring system may help sort out heterogeneity of myositis
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While a novel scoring system may aid in diagnosing myositis, the heterogeneity of this group of conditions presents ongoing challenges for clinicians, according to a presenter at the 2020 Congress of Clinical Rheumatology-East.
“I would like to discuss selected medical features of myositis classification,” Chester V. Oddis, MD, professor of medicine and director of the Myositis Center at the University of Pittsburgh Medical Center, said in his presentation.
After decades of using the 1975 Bohan and Peter classification system, authors from the ACR and EULAR published a new set of criteria for diagnosing myositis in 2017. The “robust effort from investigators around the world” led to a scoring system that is slowly being adopted by clinicians, according to Oddis.
While he did not review the document in its entirety in his presentation, Oddis said it includes a web calculator to help physicians arrive at a total myositis score. “You get points whether you have a biopsy or do not have a biopsy,” he said. “You also get more points for having a rash rather than just having [muscle] weakness.”
With the new criteria, a muscle biopsy is necessary if a patient presents without a classic dermatomyositis rash, according to Oddis. “These criteria provide a score and a probability,” he said.
Understanding rashes
Digging deeper into dermatomyositis rashes, Oddis said clinicians should be prepared for a range of presentations, from vasculitic-appearing lesions to those that resemble psoriasis. He added that a rash on the scalp may signify a patient with particularly refractory disease.
Patients may also have rashes that present as a “V-neck” or “shawl,” according to Oddis. “If you have a patient with one of those rashes, it is adult dermatomyositis,” he said. “It is easy to see. But it is not easy to treat.”
The reason for this is treatment paradigms for cutaneous-dominant disease are not evidence-based. Oddis said basic sun protection and topical agents may be used in less severe cases, while calcineurin inhibitors or tacrolimus should be considered for more aggressive disease.
Oral glucocorticoids also are in the mix, but Oddis stressed that prednisone should ultimately be tapered, which can lead to the next critical decision. If the patient responds poorly, a cross-section of second-line therapies may be considered, including methotrexate, mycophenolate mofetil (MMF), IV immunoglobulin (IVIG), tacrolimus, cyclophosphamide or rituximab (Rituxan, Genentech).
A body of evidence is emerging supporting apremilast (Otezla, Amgen) in severely refractory disease, according to Oddis. “Whatever works for psoriatic skin disease is probably going to work for dermatomyositis,” he said.
Beyond the skin
Turning to adult polymyositis, for Oddis, the diagnostic challenge is not just about understanding myositis presentations, which can range from endocrinopathies, drug-related myopathies or metabolic disorders. “You also have to worry about the mimics,” he said.
But there is a way to resolve these issues. “The point I want to make when it comes to polymyositis is that you need to do the muscle biopsy,” Oddis said.
Once a diagnosis is made, treatment challenges can continue. For example, patients with necrotizing myopathy can be a difficult autoantibody subset to treat. “IVIG might be the drug of choice for necrotizing myopathy,” he said. “They may [also] actually respond to B cell depletion with rituximab.”
Patients with anti-synthetase syndrome may have lung dominant disease, according to Oddis. “In some cohorts, pulmonary disease is frequently the most common cause of death,” he said. He added that, perhaps more troublingly, this patient population may never actually develop myositis symptoms.
For patients with myositis-associated interstitial lung disease, tacrolimus is a therapy that Oddis says may have utility. “Rituximab may also benefit pulmonary parameters,” he said.
Looking more broadly at biologic interventions in myositis populations, a “sequential approach” using different targeted agents may be the way forward. However, Oddis stressed that caution is always warranted when managing the broad spectrum of myositis. “Whether it is lung, whether it is muscle, whether it is skin, I hope I have convinced you that there is a lot of heterogeneity in myositis,” he said.
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Oddis CV. Update on Inflammatory Myopathy. Presented at: Congress of Clinical Rheumatology-East annual symposium; September 10-13, 2020 (virtual meeting).
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