Frequent nuclear expression of β-catenin protein but rare β-catenin mutation in pulmonary sclerosing haemangioma.

Background: Pulmonary sclerosing haemangioma is an uncommon tumour that is composed of glandular/ papillary lining cells and polygonal cells. The biological behaviour of this tumour has been investigated; however, the molecular pathogenesis of PSH remains unknown. Aims: To characterise the role of the Wnt/β-catenin pathway in the genesis of PSH. Methods: 37 PSH samples were investigated immunohistochemically for detection of the β-catenin protein and direct sequencing of exon 3 of the β-catenin gene. Results: Nuclear expression of β-catenin was found in the lining component of 23 tumours (62%) and in the polygonal component of 11 tumours (30%). The expression of β-catenin was stronger in the lining component, but weaker in the polygonal component. Interestingly, all the tumours with expression of β-catenin in the polygonal component also expressed β-catenin in the lining component. However, mutation of exon 3 of the β-catenin gone was detected in only one tumour that expressed nuclear β-catenin in lining and polygonal components. Conclusions: The Wnt/β-catenin pathway is involved in the genesis of PSH, but mutation of exon 3 of the β-catenin gene rarely contributes to the activation of the Wnt/β-catenin pathway in PSH. [ABSTRACT FROM AUTHOR]