[Bronchopulmonary hamartomas, chondromas, fibromas and myxomas].

The observation of 23 bronchopulmonary hamartomas, 9 chondromas, one fibroma and one myxoma has provided insight into the particularities of these tumors. The group of hamartomas, tumors of "erroneous mixture of tissue", included 20 cases which can be considered a malformation of the entodermal bronchial anlage, and 3 cases which can be regarded as a malformation of the mesenchymal anlage. The first type consists of multiple cleft-like spaces surrounded by ciliated and cuboidal epithelium. There are no alveolar cells. Cartilaginous, fibrous, myxomatous and lipomatous tissue and lymphocytes are also found. The second type consists mainly of undifferentiated mesenchymal cells with tubules, lined by cuboidal epithelial cells or an intestinal type of mucus-secreting epithelium. There may be some immature alveoli, but no ciliated epithelium is found. In contrast to the hamartomas, the chondromas are not derived from a dysontogenetic malformation of the bronchopulmonary tissue but are tumors which develop directly from the bronchial cartilage and are for this reason mainly localized in the endobronchial region. A special form seen in one case is association of pulmonary chondromas, gastric leiomyomas or leiosarcomas and extra-adrenal paraganglioma, though the latter is not always present.