SSPE-like inclusion body disorder in treated childhood leukemia.

Clinico-pathological report on a boy with cytostatically treated leukemia, dying with cerebral symptoms after passing clinical measles 10 weeks before death. At autopsy, numerous nuclear inclusion bodies in glial and nerve cells were found. By electron microscopy, nuclear inclusions appeared as loosely arranged smooth tubules, corresponding to paramyxovirus nucleocapsids. Frequently, cytoplasmic changes appeared too, consisting of incomplete tubular structures and an abundant dense "fuzzy" material. No regular tubuli of the coated granular type were present, as in common measles virus infection, nor any mature viral structures or differentiation of the surface membrane. The lack of maturation in cytoplasm together with a predominance of nuclear changes suggested a slow type of measles virus infection, while the particular cytoplasmic changes suggested a defect in synthesis of granular nucleocapsids, possibly a basic factor for the slow type of the viral infection. Possible pathogenetic factors are discussed.