Probable malignant transformation of a pulmonary hamartoma.

HISTOLOGICAL EXAMINATION The round tumour consisted of chondromatous islands separated by loose, partly myxomatous connective tissue with areas containing fat cells, and clefts lined with small cylindrical or cuboid epithelial cells. Cilia were seen in some places on the surface of the epithelial cells. About three-quarters of the tumour consisted of this typical hamartoma-like picture, and the periphery was here well demarcated and surrounded by compressed lung tissue. Fig 1 An area from edge of tumour. In lower right corner is typical cartilage-containing hamartoma. Arrow shows typical malignant tumour tissue surrounding an island of cartilage. Haematoxylin and eosin X25 (original specification).