In vivo evaluation of facial papule dermatoses with reflectance confocal microscopy in children.

Background: Molluscum contagiosum (MC), milia, keratosis pilaris (KP), verruca plana (VP), seborrheic keratosis (SK), and juvenile xanthogranuloma (JXG) are common papule dermatoses on the face of children that have a similar appearance. In vivo evaluation of facial papule dermatoses with reflectance confocal microscopy (RCM) is helpful in the diagnosis of these ambiguous lesions in children. The purpose of this study was to clarify the RCM characteristics of MC, milia, KP, VP, SK, and JXG and explore the clinical application value of RCM for these common facial papule dermatoses.

Methods: We recruited 113 patients referred for unequivocal facial papule dermatosis, including 21 patients with MC, 17 patients with milia, 19 patients with KP, 36 patients with VP, 8 patients with SK, and 12 patients with JXG. We evaluated the characteristics and distinguishing features of the six kinds of facial papule dermatoses using RCM.

Results: The main RCM features of the six dermatoses included a well-demarcated border of the lesion area. MC, milia and KP all manifested cyst-like structures, and their distinguishing features were the location of the cystic structures and the refractive index of the contents. Although VP, SK, and JXG did not have obvious cystoid structures, VP was typically characterized by uniformly distributed petal-like structures with a medium-to-high refractive index in the epidermis. With regard to SK, the characteristic features were an obviously thickened epidermis and cobblestone-like structures. JXG was mainly characterized by multiple large round and ovoid cells with a foamy cytoplasm, and discoid-shaped multinucleated large cells were diffusely distributed in the dermis.

Conclusion: RCM allows the real-time visualization of major key diagnostic and distinguishing features of common facial papule dermatoses in children, including MC, milia, KP, VP, SK, and JXG.