Pulmonary sclerosing hemangioma: sometimes a form of pulmonary hamartoma.

Previous light and electron microscopic examinations of sclerosing hemangiomas of the lung have raised questions regarding their varying microscopic patterns and cells of origin. We describe two additional cases: one studied by light microscopy revealed the classic pattern of a sclerosing hemangioma of endothelial origin, and a second, studied by combined light and electron microscopy, had incomplete small peripheral airways and occasional alveolar-like spaces derived from epithelial and mesothelial cells. It is concluded that sclerosing hemangiomas of the lung may sometimes consist of admixtures of tissues of epithelial, mesothelial, and endothelial cell origins and thus represent a form of pulmonary hamartoma.