Case 183. Molluscum contagiosum (45 y-o F)
Multiple dome-shaped perineal nodules (biopsy)
Key words : molluscum virus, molluscum contagiosum
sexually transmitted infection
The squamous cells showing localized downward growth contain eosinophilic cytoplasmic inclusions (HE, low power). Sebaceous gland involvement indicates that the molluscum lesion occurred at the site of hair follicle.   Note the change of stainability of the "molluscum body". In the granular layer, the inclusions are eosinophilic and granular, but in the cornified (parakeratotic) layer, they become homogeneous and increase basophilia (HE, high power).
Electron micrograph of the molluscum body. Numerous oval-shaped particles are seen. This double-stranded DNA virus of pox virus group belongs to the largest virus, and measures about 300 nm in the long axis.   High power electron micrograph demonstrates typical features of molluscum virus, consisting of the outer envelope and internal dumbel-shaped electron-dense nucleoid.