Nailfold videocapillaroscopy abnormalities in autoimmune inflammatory myopathy subsets

Area of Science:

• Rheumatology
• Dermatology
• Neurology

Background:

• Autoimmune inflammatory myopathies (AIM) encompass a group of rare, severe muscle diseases.
• Nailfold videocapillaroscopy (NVC) is a non-invasive technique that visualizes capillaries.
• Previous studies suggest NVC alterations in certain AIM subsets.

Purpose of the Study:

• To characterize Nailfold videocapillaroscopy (NVC) abnormalities across different autoimmune inflammatory myopathy (AIM) subsets.
• To correlate NVC findings with clinical and serological data in AIM patients.
• To assess the utility of NVC in differentiating between AIM subtypes.

Main Methods:

• A prospective cohort of 99 autoimmune inflammatory myopathy (AIM) patients from the Canadian Inflammatory Myopathy Study (CIMS) was analyzed.
• Nailfold videocapillaroscopy (NVC) images were captured using X200 magnification.
• Capillary density, ectasias, giant capillaries, ramified capillaries, and microhemorrhages were quantitatively and semi-quantitatively scored. Standardized NVC patterns were described and compared across AIM subsets.

Main Results:

• Decreased capillary density was the most common NVC abnormality, observed in 95% of dermatomyositis, 92% of scleromyositis, and 87% of anti-synthetase syndrome cases.
• Overall, 44% of AIM patients exhibited abnormal NVC, 25% had non-specific abnormalities, and 30% had normal NVC.
• NVC abnormalities were notably absent in immune-mediated necrotizing myopathy, inclusion body myositis, and polymyositis.

Conclusions:

• Dermatomyositis, scleromyositis, and anti-synthetase syndrome frequently display NVC abnormalities.
• No specific NVC pattern reliably distinguished between dermatomyositis, scleromyositis, and anti-synthetase syndrome in this cohort.
• NVC appears valuable in distinguishing the aforementioned AIM subsets from immune-mediated necrotizing myopathy, inclusion body myositis, and polymyositis.