The authors report a case of a 4-year-old child whose death resulted from acute lymphoblastic leukemia (ALL) and giant-cell pneumonia. Typical lung tumorlets were occasionally observed. On electron microscopy study it was possible to demonstrate a large number of neurosecretory granules in the tumorlet's cells, identical to those present in Kulchitsky's cells. These studies suggest the occurrence of an abnormal immunitary process
