Smooth muscle hamartoma of the lungs in a Wistar Hannover rat

Hamartomas are tumor-like masses comprising disorganized normal tissue elements. To date, spontaneous hamartomas have been reported in several organs and tissues rodents but not the lungs. Here, we report first case of a hamartoma lungs 108-week-old female Wistar Hannover rat. Grossly, white spot, 7 mm diameter, was observed on costal surface left lung. Histopathologically, nodular lesions adjacent to bronchioles comprised mature smooth muscle cells. The lesion encapsulated spread along alveolar walls ducts without compression surrounding tissue. In nodules, elastic fibers enclosed small lumens lined with factor VIII-related antigen-positive endothelial This structure suggested that nodule mimicked an artery. Moreover, structural abnormalities were within arterioles owing increased number cells tissues. These features this malformation rather than neoplasm, leading diagnosis