Objective: To evaluate the frequency and the specificity of nail changes associated with connective tissue diseases (CTD).
Methods: In a case-control study, 190 patients including those with systemic lupus erythematosus (SLE; 56), rheumatoid arthritis (RA, 47), primary Sjögren's syndrome (pSS; 35), systemic sclerosis (SSc; 39), and dermatomyositis/polymyositis (DM/PM; 13) were enrolled in the study. Patients with SLE and other CTDs were compared with two different control groups. Twenty nails were examined. Nail features were noted and classified. Nail samples were collected for mycological cultures.
Results: In patients with SLE, erythema of proximal nailfold (P<0.01), splinter haemorrhages in fingernails (P<0.01), capillary loops in proximal nailfold (P<0.05), periungual erythema (P<0.05), and thin nail plates (P<0.05) were more common than those in controls. Only splinter haemorrhages were associated with the disease activity. In patients with SSc and DM/PM, splinter haemorrhages (P<0.05) and capillary loops in proximal nailfold (P<0.01) in fingernails were common as well. Increase in longitudinal curvature (P<0.001), transverse curvature (P<0.01), and white dull colour in fingernails were other frequent findings in patients with SSc. Increase in transverse curvature was associated with the disease activity in SSc. In patients with RA, splinter haemorrhages (P<0.05), red lunula (P<0.05), and white dull colour (P<0.05) in fingernails were frequent. The sensitivity values of all these changes were very low. However, their specificity values were found to be relatively high.
Conclusion: Proximal nailfold is the most important site of affection in CTDs. These nail changes can be used in combination with highly sensitive diagnostic modalities to establish an accurate diagnosis.