Giant cell pneumonia in Letterer-Siwe disease.

An 8 month-old girl suffered from Letter-Siwe disease since one week after birth. During the chemotherapy, giant cell pneumonia caused by measles virus infection developed and led rapidly to her death. Histopathologically, alveolar spaces were lined by multi-nucleated giant cells with intranuclear and intracytoplasmic eosinophilic inclusion bodies. Electronmicroscopical examination of the lung revealed intranuclear inclusion bodies full of rod-shaped structures characteristic to paramyxoviruses, and irregular electron-dense materials compatible with nucleocapsid protein antigens in the cytoplasm. Additionally these giant cells were observed in the salivary glands, thyroid gland, thymus and lymph nodes. The measles virus antigen was detected immunohistochemically in these giant cells in the lungs and other organs. The specific antibody of measles virus is helpful to study the pathogenesis of giant cell pneumonia.