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The Korean Journal of Pathology 2003;37(1): 10-14.
Immunoexpressions of Thyroid Transcription Factor-1 and bcl-2 in Congenital Cystic Adenomatoid Malformation.
Na Rae Kim, Dong Hoon Kim, Gou Young Kim, Dae Shick Kim, Joungho Han
1Department of Pathology, Kangnam General Hospital Public Corporation, Seoul, Korea.
2Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. jhhan@smc.samsung.co.kr
BACKGROUND: Congenital cystic adenomatoid malformation (CCAM) is a congenital abnormality of branching morphogenesis of the lung. Thyroid transcription factor-1 (TTF-1) is detected in human respiratory epithelial cells from 11 weeks of gestation, and at full term, TTF-1 expression is confined within type II epithelial cells and in some respiratory nonciliated bronchiolar epithelial cells. Immunoexpression of bcl-2 is intimately related to apoptosis during the development. METHODS: To elucidate the nature of the lesion, TTF-1 expression was evaluated in twenty-four cases of CCAM (eight cases of type 1 and sixteen cases of type 2) along with immunostaining for bcl-2. For the control group, four cases of fetal lungs (19 week-, 21 week-, 27 week- and 40 week-gestational age) were also evaluated. In all cases of CCAM, TTF-1 was detected in the nuclei of epithelial cells lining the cysts. RESULTS: TTF-1 was expressed in the majority of the bronchiolar-like epithelial cells of the cysts in CCAM types 1, and 2, where almost 100% of the lining cells of the cysts were TTF-1 positive with variable intensity, while negative TTF-1 expressions were found in the alveolar-like epithelium of the adjacent alveoli or distal nonciliated bronchi. For bcl-2 immunostaining, no lining epithelial cells of the cysts were stained except for the infiltrating lymphocytes. In the control group, strong immunoreactivities found in early fetal stages were absent in the full-term aged lung (40 gestational weeks). CONCLUSION: These results support the hypothesis that CCAM types 1 and 2 reflect the abnormalities in lung morphogenesis and differentiation that are distinct from those for normally developed alveolar epithelium or adjacent bronchial epithelium, thus retaining the abnormal TTF-1 immunoreactions. Though restricted to CCAM types 1 and 2 in this study, CCAM might be related to TTF-1 rather than apoptosis in the morphogenesis of the developing lung.
Key Words: Cystic adenomatoid malformation of lung, congenital; Thyroid transcription