Clinical Presentation
All patients with the SAE autoantibody had skin involvement, and more than half of the patients initially presented clinically with amyopathic dermatomyositis. In patients who eventually developed muscle disease, the muscle involvement occurred as long as 17 months later and tended to be mild. Approximately half (53%) of the patients with the anti-SAE antibodies complained of subjective muscle weakness, and 42% had weakness on examinationMany of the patients with anti-SAE antibodies had inflammatory arthritis and tenosynovitis, and some developed joint contractures.
The cohort included two patients with cancer diagnosed close to the onset of dermatomyositis symptoms: One 66-year-old woman was diagnosed with poorly differentiated carcinoma within three months of her dermatomyositis diagnosis, and one 60-year-old man was diagnosed with moderately differentiated adenocarcinoma of the colon contemporaneous with his dermatomyositis diagnosis. Three other patients in the cohort were diagnosed with cancer more than five years after dermatomyositis symptom onset. Given the small numbers, the study could not confirm an association between anti-SAE antibodies and cancer, but the researchers feel the coincident cancer cases justify judicious malignancy screening.
Lungs: Dr. Albayda says the lung findings surprised her the most. Often, for patients with amyopathic or hypomyopathic dermatomyositis, lung involvement can be so severe that it may be the cause of demise. In contrast, for the patients with anti-SAE dermatomyositis who appeared to be amyopathic, “none of them really complained about lung symptoms,” she says.
Nevertheless, most of the nine patients who had available chest computed tomography (CT) scans had some form of lung involvement even though they had normal to mild restriction in pulmonary function tests. In fact, the investigators had difficulty classifying the interstitial lung disease in these patients and found a novel pattern of peripheral nodules. Although there is always concern about cancer in patients with lung involvement, Dr. Albayda notes none of the patients with lung nodules developed lung cancer. She and her colleagues believe the nodules may reflect an inflammatory process in the lungs, and it has been reassuring that the process appears unlikely to progress to severe lung disease.
Dr. Albayda contrasts the lung findings in patients with anti-SAE dermatomyositis with those of a different subset of patients, those with amyopathic dermatomyositis who can also present with fulminant lung disease. Dr. Albayda suggests knowing the antibody involved can be helpful in predicting disease course. “Antibodies are describing a distinct group within a larger spectrum,” she says.
