Pulmonary adenomatosis in ageing mice

Data were collected at the time of autopsy from 101 cases of pulmonary adenomatosis in female CD-1 mice. Three groups were studied: controls, animals inoculated with live Ehrlich ascites tumour cells subcutaneously or intraperitoneally and those explanted with fragments from various spontaneous murine tumours. The average age at death was essentially the same in all three groups. Similarly, there was no significant difference in tumour incidence between controls and EAT-treated mice. By contrast, the incidence of adenomatosis in mice explanted with fragments of tumour was significantly greater than that in the controls or in the EAT-treated animals. Microscopical studies from the tumourous lungs indicate that these neoplasms are typically dual in nature. There are darkly staining areas of tubular carcinomatous tissue, often transformed into cords by complex papillations; these are derived from anaplastically transformed bronchiolar lining. Else-where in the same tumours there are lightly staining cell clusters derived from alveolar lining elements. Desquamation from the anaplastic alveolar linings is common. The free cells of an alveolar macrophage type are carried through the pulmonary air passages and can appear in non-tumourous regions of the lung. It is suggested that this mechanism may be a means of establishing secondary tumour foci. Metastasis in organs other than the lung itself were found in 7 mice.