Keratoacanthoma in a smallpox vaccination site

Tumours arising at the site of smallpox vaccination are rare. A case of keratoacanthoma developing within 2 months at the site of vaccination is described and a likely role of vaecinia virus in the causation of such a tumour is discussed. Complications of varying type and severity may follow smallpox vaccination. Except for encephalitis, these are not officially notifiable diseases, and thus available statistics on their incidence are often un-reliable; however, a primary tumour developing in the site of vaccination is certainly rare. Lane et al. (1970) in 1,648,000 vaccinations against smallpox described one patient who developed melanoma. We describe here a case of keratoacanthoma developing within 2 months at the site of a successful primary vaccination.