**8.2 Dermatomyositis (DM) and polymyositis**

The scleroderma pattern is observed in 20–60% of patients with more frequent and pronounced findings in dermatomyositis [31]. Juvenile dermatomyositis (JDM) can reveal phasic changes on NFC. Early stages of microhemorrhages and giant capillaries are followed later by capillary loss and neoangiogenesis [32]. In dermatomyositis, these phasic changes are less obvious. Interestingly, shorter duration of disease is associated with more sever changes—giant capillaries and reduced capillary density. Longer duration of disease is typified by the presence of extensively ramified capillaries [33]. There also appears to be a strong correlation between the NFC involvement and cutaneous activity [34]. In JDM patients, lack of resolution of NFC changes is associated with the more severe and chronic forms of the disease [32]. An association has also been described between capillary abnormalities and ILD, Raynaud's, and malignancy [35]. However, currently the data correlating with disease activity is sparse to formulate any definitive recommendations.
