Nicolau's syndrome induced by intramuscular vaccinations in children: report of seven patients and review of the literature.

BACKGROUND: Nicolau's syndrome (NiS), or embolia cutis medicamentosa, is a rare condition characterized by the acute onset of cutaneous and soft-tissue necrosis following intramuscular drug injection. Intramuscular injections are the main route for vaccinations in children.
METHODS: This is a retrospective study of seven children (mean age 9.8 months) who developed NiS subsequent to intramuscular vaccination.
RESULTS: The reactions were observed after different combinations of vaccine antigens, and were no more common after repeated than after primary injection of the respective vaccine. Three children developed scars without functional impairment, two made a full recovery, and the final outcome is unknown for four.
CONCLUSION: Given the high prevalence of intramuscular injections during infancy, NiS seems to be a rare event, but there is a possibility of under-reporting of less severe reactions. Our retrospective data do not allow a true risk assessment. The most worrying aspect of NiS, however, is its lack of predictability. As long as complete avoidance of the intramuscular route is not an option, it is obvious that NiS cannot be completely prevented.