Immunohistochemical study of thyroid transcription factor-1 and surfactant-associated protein A for investigation of peripheral airway structure in perinatal fatality

We studied histopathological findings of the lungs in four cases where there was a suspicion of infanticide whereby an autopsy was performed. All four babies were born in full term delivery. It was difficult to discern whether the peripheral airways of the lungs were open or closed with conventional histological examination. Therefore immunohistochemistry with a combination of anti-thyroid transcription factor-1 (TTF-1) and anti-surfactant-associated protein A (PE-10) was used in order to elucidate the fundamental structures of the peripheral airways. TTF-1 highlighted nuclei of Clara cells and type II alveolar cells. The findings of immunohistochemistry with TTF-1 enabled us to more objectively recognize the peripheral airways: respiratory bronchioles and alveolar ducts, even in collapsed lungs. PE-10 was expressed in the cytoplasm of Clara cells, type II alveolar cells and the substance of air space. Aspect for immunohistochemistry with PE-10 appeared to be granular in closed air space, whereas it appeared to be stretched membranously along the interalveolar septa in open air space. These findings suggest that application of immunohistochemistry with TTF-1 and PE-10 is a useful diagnostic tool in judging perinatal fatality.