Preliminary evaluation of penile papule dermatoses with reflectance confocal microscopy in children

BACKGROUND: Owing to their similar appearance, lichen striatus (LS), lichen nitidus (LN), juvenile xanthogranuloma (JXG), and molluscum contagiosum (MC) on the penis often lead to misdiagnosis and missed diagnosis, especially in children. In vivo evaluation of penile dermatoses with reflectance confocal microscopy (RCM) is helpful in the diagnosis of these ambiguous lesions in children. METHODS: We recruited 12 patients with LS, nine with LN, seven with JXG, and nine with MC and evaluated the characteristics and distinguishing features of the four kinds of papule dermatoses on the penis using RCM. RESULTS: The four dermatoses all had unique RCM features. LS generally showed focally destroyed dermal papillary rings, with numerous mononuclear cell clusters aggregated inside the papillary rings, and highly refractive clumps were observed. For LN, the dermal papillary rings were completely destroyed and arranged in a solitary, enlarged, cavity‐like structure, in which round cells, particulate matter structures, and plump cellular structures were aggregated; the adjacent skin was completely normal. In JXG, the dermal papillary rings were significantly dilated, and the superficial dermis was filled with different‐sized large bright ring cells; smaller, refractive, roundish structures; and particulate matter. For MC, the normal structures completely disappeared; the lesions were arranged in a crater‐shaped structure; and a mass‐like substance formed by the aggregation of multiple, uniform, roundish structures was observed within the crater. CONCLUSION: RCM allows for real‐time visualization of major key diagnostic and distinguishing features of four papule dermatoses, LS, LN, JXG, and MC, on the penis in children.