Extramedullary hematopoieisis (EMH) were found in the liver and spleen in 101 cases among 629 autopsy cases of malignant neoplasm. Statistical observation, macroscopic and microscopic findings in the liver and spleen, the relationship between EMH and the bone marrow metastasis of the malignant neoplasm, the relationship between EMH and the leukemoid reaction and so on were studied.
The results are as follows.
1) The frequency of the development of EMH found in cases of malignant neoplasm is a little higher than those of the marrow metastasis.
2) The number of EMH in cases of bone marrow metastasis is four times more frequent than that in cases of non bone marrow metastasis.
3) The average weight of the spleen in cases of EMH is 20 g heavier than that in cases of non EMH. But as to the weight of the liver no great difference is found between both.
4) The degree and frequency of EMH in the liver and spleen are different in many cases. Generally speaking, EMH in the spleen is more frequent and more marked than that in the liver.
Considering the weight of both organs, the total volume of EMH in the liver is greater than that in the spleen. The stagnation and metastasis of malignant neoplasm in the liver may be partly responsible for the fact that the degree of EMH in the liver is less marked than in the spleen.
5) As to G/E ratio in the foci of EMH, cases of E>G are two times more frequent than those of G<E.
In cases of leukemoid reaction, however, cases of G>E are two timer more frequent than those of E>G conversely.
6) The f requence and degree of EMH are to some extent parallel to the extent of the metastasis in the body. It may be said that the more extensive is the extent of hematogenous and lymphogenous metastasis, the higher the frequency and degree of EMH.
7) In most cases of leukemoid reaction the bone marrow metastasis and EMH in the liver and spleen are found.
From this fact there may be the close relation between these events.
But in a few cases of leukemoid reaction there are no bone marrow metastasis and EMH. Therefore EMH is not an indispensable factor in the development of the leukemoid reaction.
8) From the above-mentioned facts, it may be said that colonisation theory, that is, that hemopoietic undifferentiated cells enter into the blood by the destruction of the bone marrow and other factors, lodge in the mesenchymal tissue in the liver and spleen and multiply there, is more appropriate.
But the decisive conclusion remains obscure and further studies into this problem are encessary.
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