Is sclerosing hemangioma of lung an alveolar mixed tumour?

A case of a peripheral lung tumour histologically categorized as a sclerosing hemangioma of the lung is presented. Ultrastructurally, the tumour is composed of a mixture of epithelial and mesenchymal elements in varying stages of differentiation. Type II pneumocytes are identified as one epithelial component, while primitive mesenchymal cells with a tendency to develop into pericytes are the predominant mesenchymal component. The tumour appears to differentiate along the line of the pulmonary alveolar septa, and should be designated as a 'pulmonary alveolar mixed tumour'.