General: infection of epidermal cells with poxvirus, most common in children


Pathogenesis: can spread by intimate contact, virus replicates within keratinocytes and forms large bodies in the cytoplasm, center of lesion disintegrates


HPI: pediatric patient with rash, adult with sexual history and genital lesions, patient with HIV/AIDS


Physical exam: smooth, small, flesh-colored, dome-shaped papules with central umbilication, can be single lesions or multiple, can progress to large number of lesions 


Differential: basal cell carcinoma (older patients, telangiectasia), central umbilication is key!


Histology: biopsy usually not necessary, but you can remove papule and crush onto a slide, will see molluscum bodies (sacs containing virions) and thickened epidermis 


Complications: lesions can persist for years or become inflamed, can involve eyes to cause conjunctivitis, dissemination in immunosuppressed patients 


Treatment: (1) spontaneous resolution within months, if not resolving (2) cryotherapy, (3) salicylic acid,  or (4) cantharidin (chemical blistering), *goal of treatment if necessary is to destroy the lesion*


References: AAD Basic Dermatology Curriculum, Dermatology by Bolognia et. al., Lookingbill and Mark's Principles of Dermatology, First Aid USMLE Step 1 2020, First Aid USMLE Step 2 CK