Diagnostic Application of Bedside Reflectance Confocal Microscopy in Viral Skin Diseases: A case series

To summarize the reflectance confocal microscopy (RCM) characteristics of various viral infectious skin diseases and enhance their early diagnostic rates.

A total of 120 patients with different viral infectious skin diseases (including 30 cases of typical herpes zoster, 25 cases of atypical herpes zoster, 20 cases of herpes simplex, 8 cases of kaposi's varicella-like rash, 20 cases of adult hand, foot, and mouth disease, 10 cases of Orf, and 7 cases of Mpox in the genital area) who visited the dermatology outpatient department from October 2022 to July 2024 and were diagnosed through clinical and laboratory examinations were selected as the study subjects. Their RCM images were retrospectively collected, and their RCM characteristics were analyzed to summarize their common and unique microscopic manifestations.

(1) The common RCM feature of the 120 patients included in the study is the presence of medium-sized to large-sized typical or atypical disc-shaped cells in the epidermis. (2) New findings of this study: In the RCM of early atypical herpes zoster, intercellular filiform connections ("tadpole sign") can be observed; in herpes simplex and kaposi's varicella-like rash, RCM is more likely to show aggregation of neutrophils; in adult hand, foot, and mouth disease, RCM reveals multivesicular vesicles ("honeycomb sign"); in Orf,RCM shows small round particles with high refractive index and "starry sky sign"; in genital Mpox, RCM reveals atypical disc-shaped cells presenting a vesicular appearance.

RCM holds significant diagnostic value in the early screening of viral infectious skin diseases.