Bull's eye dermatoscopy pattern at bacillus Calmette–Guérin inoculation site correlates with systemic involvements in patients with Kawasaki disease

For the past decades, although the rash at the bacillus Calmette–Guérin (BCG) inoculation site has been recognized as a diagnostic clue in Kawasaki disease, the present study is the first known one attempting to characterize BCG inoculation by dermatoscopy in Kawasaki disease and correlate the grade of BCG reaction with systemic involvement. Thirty-four patients diagnosed with Kawasaki disease by pediatric specialists were enrolled. We performed detailed history taking, laboratory examination, physical examination and dermatoscopy examinations. Based on the BCG reaction pattern by dermatoscopy, we were able to characterize three patterns: (A) Bull's eye pattern in 18 patients; (B) faint homogenous erythema in nine; and (C) central white patch in seven. Patients from group A exhibited the highest elevation of blood aspartate aminotransferase levels (P < 0.05). Notably, three patients from group A had a significantly dilated coronary artery despite i.v. immunoglobulin injection. We concluded that the bull's eye dermatoscopy sign is not only a useful diagnostic clue but also a severity biomarker in patients with Kawasaki disease.