Giant cell pneumonia: light microscopy, immunohistochemical, and ultrastructural study of an autopsy case.

An autopsy case of measles giant cell pneumonia with intranuclear inclusion bodies is reported. This case of giant cell pneumonia was studied by light microscopy and immunohistochemistry using monoclonal and polyclonal antibody to measles and by electron microscopy (EM). Light microscopic examination showed multinucleated epithelial giant cells with intranuclear and intracytoplasmic inclusions. The giant cells contained prominent, sharply marginated, eosinophilic intranuclear inclusions typical of classic measles pneumonia. Presence of measles antigen was confirmed using both monoclonal and polyclonal antibodies by peroxidase antiperoxidase method. Monoclonal antibody stained positively for intracytoplasmic and intranuclear inclusions. Electron microscopic examination of lung tissue showed intranuclear inclusions of filamentous or worm like nucleocapsid materials in multinucleated epithelial giant cells. The results suggest that this is a case of measles giant cell pneumonia and the intranuclear inclusion bodies are measles viral particles.