[A study on development site of pleomorphic adenoma--a rare case report in external nose]

A rare case of pleomorphic adenoma in the external nose is reported. As a result of studies on the correlation between the sites of occurrence of pleomorphic adenomas reported and the sites of secretory glands with myoepithelial cells, it is found that pleomorphic adenomas occur in all secretory glands with myoepithelial cells. There are distinctive differences in the incidence in each part of the body, and in the hollow organs in the digestive and respiratory tracts: it is high in the face and decreases as the sites become farther away from the face. In the integumentary system, it is also high in the face. However, pleomorphic adenomas occurring in secretory glands without myoepithelial cells, and in non-glandular tissue such as the middle ear, paranasal sinuses, mesangial sinuses, vagina and tests can be considered either as those where glandular tissue and myoepithelial cells mingled during development (and thus are ectopic) or as those when invasion into adjacent organs occurred as the pathologic lesion (pleomorphic adenoma) expanded.