Histopathological features of molluscum contagiosum other than molluscum bodies

Classic histopathological features of molluscum contagiosum (MC) include a crateriform, acanthotic epidermis containing intracytoplasmic molluscum bodies (MBs). In our experience, a subset of cases lack these features on initial haematoxylin and eosin-stained sections. We aimed to describe the histopathological features of MC other than those classically described.

Sixty-seven biopsies diagnosed as MC from January 2011 to October 2012 were retrospectively reviewed. Keratinocytes peripheral to the diagnostic cells with MBs had prominent nucleoli (67; 100%), amphophilic cytoplasm (54; 81%), and in many instances clear cytoplasmic vacuolization (38; 57%). Stroma surrounding MC lesions showed fibroedematous to fibromyxoid changes in many cases (36; 54%), with a subset (13; 19%) showing abundant dermal mucin. In eight of 67 cases (12%), initial sections did not possess MBs or crateriform epidermis of MC. In these cases, initial sections revealed only the epithelial and/or perilesional stromal changes described above. Additional sections contained MBs in all of these cases.

Perilesional fibroedematous to fibromyxoid stroma and keratinocyte changes, including prominent nucleoli and amphophilic cytoplasm with clear vacuolization, are common in MC. Recognizing these features may prove helpful in reaching the diagnosis of MC in cases lacking classic histopathological features on initial sections.