Molluscum Contagiosum : Differential
Molluscum Contagiosum - Differential Diagnosis: The diagnosis of molluscum contagiosum (MC) can be rendered in most cases by clinical examination. Similarly, the histopathologic features of MC are straightforward and easily recognized in non-disrupted lesions. The differential diagnosis of MC in various clinical contexts is as follows: multiple small lesions have to be distinguished from flat warts, condyloma acuminata, syringoma, and sebaceous hyperplasia. Large solitary mollusca may mimic squamous cell carcinoma, keratoacanthoma, basal cell carcinoma, and epidermal inclusion cyst. Multiple facial mollusca in HIV+ individuals have to be distinguished from disseminated invasive fungal infections, including cryptococcosis, histoplasmosis, and coccidioidomycosis. In typical lesions of MC, there is no dermal infiltrate. However, if the lesion ruptures and inclusion bodies enter the dermis, the inflammatory response may be quite intense. The dermal lymphoid infiltrate may contain CD30+ large atypical cells and mimic a CD30+ cutaneous lymphoproliferative disorder. This high magnification view shows progressive histologic changes in MC lesions as the virus replicates in keratinocyte cytoplasm and inclusion bodies are formed and eventually extruded from the surface.