Six autopsy cases with multiple pulmonary granulomas caused by an hitherto unknown foreign body were reported. Underlying diseases in these cases were apoplexia cerebri, epilepsy and other brain disorders, so that the patients showed vomitting, coma or disturbed consciousness in their clinical course. 4 of 6 cases revealed clinical symptoms of boronchopneumonia.
Macroscopically, small, firm, round or irregular shaped, greyish-yellow nodules were scattered in the both lungs. In some cases, there were larger pneumonic lesions with suppuration. On histological examination, the lung nodules were granulomas with many oval foreign bodies and giant cells. These granulomas were located in the bronchioles, alveolar ducts, alveoli and septa. Surrounding areas of the granumas showed often desquamtion of the alveolar epithelial cells and exudation of blood plasma, fibrin and leucocytes in the alveoli. The alveolar septa in these areas were thickened due to cellular infiltration. At laparotomy of an additional case with duodenal ulcer, the peritoneum at the site of perforation was studded with small granulomas containing the same foreign bodies. Some of these peritoneal granulomas, however, contained also fragments of striated muscle which very probably had been ingested as foodstuff.
The foreign bodies within the pulmonary and peritoneal granulomas had various sizes and structures. The most frequent form (Type A) was oval and 50-100μ in diameter and had a translucent, refractile membrane measuring 2-5μ, Within the bodies there were many round eosinophilic granules which were 10-15μ in diameter. In some granulomas there were larger ovoid foreign bodies (Type B) with a lobulated internal structure suggesting vegetable cells. The Type C foreign bodies were consisted of polygonal meshwork in which some small oval granules were found.
Examination on histological sections and cytological smears of miso (soybean paste) showed that this foodstuff were consisted with vegetable cells which were tinctorially and structurally indentical to foreign bodies seen in the human lung and pritoneum. The structure of the predominant vegetable cells in miso were similar to that of the Type A foreign bodies in our human cases. There were also other vegetable cells corresponding to Type B and C foreign bodies.
Subcutaneous injections of cooked, destilled miso soup to the rats produced granulomatous and suppurative lesions which were similar to those seen in the human cases. This experiment indicated that the injected vegetable cells of miso soup alone can cause not only a granulomatous change, but also a marked exudative and suppurative reaction.
From these observations, it was considered that the pulmonary granulomas and surrounding pneumonic changes in our 6 cases were caused by aspiration of miso soup containing vegetable cells.