Tissue Changes In Leukaemia

The changes in the blood are associated with lesions in the tissues, some of which are generally regarded as primary, and some as secondary, although authors are not. wanting who regard all the tissue changes as secondary to those in the blood. The primary changes affect the organs which are generally regarded as concerned in the formation of the blood-corpuscles, namely, the spleen, the lymphatic glands, and the bone-marrow. Attempts have been made to divide the cases, according as the lesions have been chiefly in one or other of these organs, into a splenic, a lymphatic, and a myelogenic form, but this division can hardly be carried out, especially as the bone-marrow seems to be affected in nearly all cases.

The Spleen is affected in most cases, and when affected it is in all stages enlarged. The enlargement in the earliest period appears to be due to an active congestion, and is accordingly of rapid development. Rindfleisch mentions a case which he saw at Virchow's demonstrations in which the enlargement had been so rapid as to cause a rupture of the capsule of the spleen. This enlargement is merely from overfilling of the vessels, but it is succeeded by, or develops into, a solid enlargement. The Malpighian bodies of the spleen have the structure of lymphatic follicles, and it is mainly by their increase in size that the permanent solid enlargement occurs. There is thus a great increase of lymphoid tissue. The spleen becomes converted into a hard, denser bulky organ, sometimes like a piece of wood. It is also paler than normal, and we can often see the enlarged Malpighian bodies as whiter areas on the cut surface. In addition, there are frequently haemorrhages in the spleen, and these may take the form of the regular wedge-shaped infarctions. The capsule of the spleen is greatly thickened, and it presents not infrequently dense localized thickenings of a cartilaginous consistence. The capsule is often firmly adherent to the diaphragm and other neighbouring structures. The greatly enlarged dense, and heavy organ is frequently dislocated downwards by its own weight.

The Bone-marrow undergoes changes which in some respects are similar to those in anaemias (see p. 73), but in other respects are different. Two different conditions have been described, one in which there is a red marrow, as in pernicious anaemia, and another in which the marrow is pale, so as to resemble solidified pus. There is also in many cases an increase in the marrow at the expense of the osseous tissue, as in anaemia. The transformed marrow consists largely of lymphatic tissue composed of small round cells like those of lymphatic glands (see Fig. 22). but there are amongst these nucleated red corpuscles, and sometimes large cells with several nuclei. Haemorrhages and infarctions have been observed in the altered bone-marrow as in the spleen.

The lesion in the Lymphatic glands consists in an enlargement of them. This begins mostly in a particular set of glands usually situated externally, as in the axilla, groin, neck, etc., and spreads to other sets, generally first to those nearest. The enlarged glands may be three, five, or even ten times their normal size, but there is no tendency to any degeneration of their tissue.

In the Secondary lesions there is sometimes also a new-formation of lymphatic tissue, partaking more of the characters of tumour-formation, as it may occur in places where there is normally no such tissue present, in which case the term lymphoma is sometimes applied to the new-formation. More frequently, however, there is merely an infiltration of the connective tissue of organs with leucocytes. These may have been derived from the blood, but they appear to multiply in situ as Bizzozero has observed evidences of division (karyomitosis) in the cells.

The Liver is nearly always enlarged, and microscopic examination shows a great accumulation of leucocytes in the dilated hepatic capillaries. There is also in most cases a general infiltration of the capsule of Glisson, attaining to greater intensity at certain points, but it may be in such definitely localized areas as to suggest minute tumours.

The Kidneys are not infrequently affected, and here the appearance to the naked eye is often as if the organs were greatly enlarged by the presence of large pale tumours in the cortical substance. On microscopic examination (see Fig. 23) the lesion is seen to consist in an enormous infiltration of the stroma of the kidney with round cells, the proper secreting tissue remaining, but, of course, greatly pressed on. This infiltration occurs in definite areas, as if some agent had addressed itself to certain defined portions of the organ.

Fig. 22. - Bone-marrow in leu-ksetnia, from the cavity of the shaft of the femur. Adenoid reticulum and lymphoid cells are shown, x 350.

The Closed follicles of the intestines, both the solitary ones and those aggregated in Peyer's patches, may be enlarged, and as they are of lymphatic structure, their enlargement is a simple hyperplasia. This is not of frequent occurrence, and still less frequent is the formation of leukemic tumours in the skin, these tumours consisting of infiltrations of round cells.

Fig. 23. - Kidney in leukaemia. Many round cells are seen separating and partly obscuring the uriniferous tubules.

The connective tissue in other regions may also be infiltrated. The author met with a case in which the connective tissue of the mediastinum was enormously infiltrated, so that the tissue formed a bulky tumour. The infiltration extended to the pericardium much in the fashion of Hodgkin's disease.

It is proper here to mention that in Hodgkin's disease, which is sometimes called Pseudo-leukaemia, the organic lesions somewhat resemble those of leukaemia, but without the increase of white blood corpuscles, the blood being simply anaemic. There is great enlargement of the spleen and of the lymphatic glands, consisting as in leukaemia in a new-formation of lymphatic tissue.

Literature

Ehrlich, Arch. f. Anat. u. Phys., 1879; Zeitschr. f. klin. Med., 1880, Charite-Annal., 1884, and various other papers; Virchow, Froriep's Notizen, 1845, Gesam. Abhandl., p. 190; Bennett, Ed. Monthly Journal, 1850-51, and Leucocythsemia, 1852; Trousseau, Gaz. des hep., 1858; Mosler, Die Path. d. Leukamie, 1872, and Virch. Arch., vol. lxxv.; Neumann, Myelogene Leukamie; Berl. klin. Wochenschr, 1878, No. 6; Waldstein, Virch. Arch., vol. xci.; Biesia-decki, Wien. Med. Jahrb., 1876, p. 234; Ponfick, Virch. Arch., vol. lxvii.; Bizzozero, Virch. Arch., vol. xcix.; Zenker, Arch. f. klin. Med., xviii.; Muir, Journ. of Path., 1892, i. 123; article " Leucocythaemia" (with literature); Allbutt's System of Med., vol. v., 1898; Von Limbeck, Centralbl. f. allg. Path., II. 922., Klin. Path, d. Blut., 1896.