Thymic dysplasia, persistence of measles virus, and unexpected infant death.

A case of sudden infant death in an 18-month female infant is described which occurred 3 weeks after clinical recovery from a typical attack of measles. At post-mortem examination no obvious cause of death could be found apart from some terminal aspiration of vomit. Histologically, the thymus showed selective absence of Hassall's corpuscles with a normal number of cortical lymphocytes. There were many atypical lymphocytoid cells in the lymph nodes, spleen, and portal tracts, and measles virus was subsequently isolated from the lung and tonsil. There was a raised titre of complement fixing measles antibody (1/256).