Special Pathology 4 страница

Course. The disease is progressive; remissions are followed by exacer­bations. Anaemia and cachexia develop gradually. The prevalent affection of a particular group of lymph nodes accounts for the clinical picture of the disease. In some cases compression of a vital organ can accelerate the disease and its outcome. The patient may also die of a secondary infection. The average life expectancy of the patients is from 3 to 4 years; some pa­tients however survive for 6-8 years and more.

Treatment. Radiotherapy is quite effective. It can give remissions lasting as long as several months (after irradiation of the enlarged lymph nodes). Chemical cytostatics (usually their combinations) are used.

Haemorrhagic Diathesis

Haemorrhagic diathesis is the disease characterized by the tendency to bleeding and repeated haemorrhages; they may occur spontaneously and may be caused by injuries; injury can be quite insignificant, which other­wise would never provoke bleeding in a normal individual.

Aetiology and pathogenesis. These are quite varied. Some types of haemorrhagic diathesis are hereditary but many of them can be caused by some external factors.

Special Part

Chapter 9. Diseases of the Blood

Avitaminosis (deficit of vitamins C and P) is an especially predisposing factor. Some infections (long-standing sepsis, louse-born typhus, virus haemorrhagic fevers, icterohaemorrhagic leptospirosis), allergic condi­tions, some diseases of the liver, kidneys, and of the blood system can also provoke the onset of haemorrhagic diathesis.

Haemorrhagic diathesis can be classified by the pathogenesis into two major groups: (1) haemorrhagic diathesis due to disordered capillary permeability (haemorrhagic vasculitis, vitamin C deficiency, some infec­tious diseases, trophic disorders, etc.); (2) haemorrhagic diathesis due to disorders in the blood coagulation and anticoagulation system. The latter group is further subdivided into the following conditions:

A. Haemorrhagic diathesis caused by disordered blood coagulation
system:

(1) first phase: congenital deficit of plasma components of thrombo-
platelet formation (factors VIII, IX, XI), haemophilias A, B, C, etc.;
deficit of thrombocytic components (thrombocytopathy, e.g. throm-
bocytopenic purpura; see below);

(2) second phase: deficit of plasma component of thrombin forma­
tion—factors II, V, X, the presence of antagonists to them and of their in­
hibitors;

(3) third phase: deficit of plasma components of fibrin formation-
factors I (fibrinogen) and XII.

B. Haemorrhagic diathesis caused by accelerated fibrinolysis (due to in­
creased synthesis of plasmin and insufficient synthesis of antiplasmin).

C. Haemorrhagic diathesis caused by disseminated intravascular
coagulation (thrombohaemorrhagic syndrome or coagulopathy of con­
sumption) in which all procoagulants are utilized during massive in­
travascular coagulation and the fibrinolysis system is activated.

This concise classification of haemorrhagic diathesis is only conven­tional because several pathogenic factors are often involved. This classification covers a very large group of diseases, both hereditary and ac­quired, and also secondary syndromes arising against the background of the main disease (metastasizing malignant tumour, burn disease, etc.)

Clinical picture. The general clinico-morphological symptoms of haemorrhagic diathesis are haemorrhages into various organs and tissues, external and internal haemorrhages (from the gastro-intestinal tract, lungs, uterus, kidneys, etc.) and secondary anaemization. The disease is com­plicated by dysfunction of the haemorrhage-affected organs, by hemiparesis in disordered cerebral circulation, regional paralysis and paresis in compression of large nervous trunks by haematomas, haemar-throsis in repeated haemorrhages into the joints, etc.

Despite the great variety of haemorrhagic diatheses and certain diagnostic difficulties, accurate diagnosis is quite important for efficacious

therapy in each particular case. The aetiological and pathogenetic factors of the disease should be properly considered for an accurate diagnosis. Haemorrhagic diathesis is the subject of special study of senior medical students. Here we shall only acquaint the reader in general with throm-bocytopenic purpura (Werlhof's disease).

The prophylaxis of hereditary (familial) haemorrhagic diathesis in­cludes medico-genetic studies that may give the wife and husband the necessary information and advice concerning possible complications in their offspring; if haemorrhagic diathesis is not hereditary but acquired, measures should be taken to preclude development of diseases that may pjpmote the onset of haemorrhagic diathesis.

Thrombocytopenic purpura (Werlhof's disease). Thrombocytopenic purpura is a haemorrhagic diathesis due to the deficit of blood platelets. The disease was first described by Paul Werlhof in 1735. Throm­bocytopenic purpura occurs mostly in young females.

The aetiology and pathogenesis of the disease are unknown. It has only been established that the immune-allergic mechanism is positively involved in about 50 per cent cases: anti-thrombocytic antibodies are produced and fixed on the surface of thrombocytes to damage them and to prevent their normal separation from megakaryocytes. The triggering factors (the im­petus to production of auto-antibodies) may be infection, toxicosis, in­dividual hypersensitivity to certain foods and medicines. In some cases the disease is caused by hereditary insufficiency of certain enzyme throm-bocyte systems which is probably activated by some additional factors.

Pathological anatomy. Multiple haemorrhages in the skin and the internal organs are characteristic. The spleen may be considerably enlarged. Separation of thrombocytes from megakaryocytes in the bone marrow is disordered (according to histological findings).

Clinical picture. The main symptom of the disease is the appearance on the skin and mucosa of multiple haemorrhages in the form of small dots (petechiae) or large spots (ecchymoses). Haemorrhage may be spontaneous and due to insignificant injuries, mild contusion, pressure on the skin, etc. Haemorrhagic lesions are first purple, then they darken to cherry-red and brown, and then lighten to yellow and disappear in several days. But new lesions develop to succeed the disappearing ones. Bleeding from the nose, gastro-intestinal tract, kidneys or uterus are not infrequent; haemorrhages into the internal organs (brain, fundus oculi, myocardium, etc.) are also possible. Grave and prolonged bleedings arise in extraction of teeth or in other minor operations. The tourniquet test (and especially the pinch test) are positive. The spleen and the lymph nodes are usually not enlarged; tap­ping on the bones is painless.

Thrombocyte counts are usually less than 50 x 10⁹ per 1 1; in some cases only single blood platelets can be found in preparations. The degree

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of bleeding can be assessed by the degree of thrombocytopenia. Hypochromic anaemia can develop after profuse bleeding. The clotting time is normal in most cases, but it can be slightly longer (due to the deficit of thromboplastic factor HI of blood platelets). The bleeding time increases to 15-20 min and more; clot retraction is disordered. Throm-boelastography reveals greatly increased reaction and clotting time.

Course. Both acute and chronic recurrent forms of the disease are observed. The patient dies of profuse bleeding and haemorrhages into the

vital organs.

Treatment. Removal of the spleen is indicated in grave cases: the number of thrombocytes increases in the blood of a patient and haemor­rhage stops in a few days following the operation. The effect of splenec-tomy is probably explained by decreased decomposition of blood platelets in the spleen and by the removal of the inhibiting effect that the spleen has on thrombocytopoiesis. Blood transfusion is useful for haemostasis and blood substitution. Repeated transfusion of thrombocytic mass gives positive haemostatic effect. Vitamin P, vitamin C, calcium chloride and vicasol are given to strengthen the vascular walls. Since the allergic factor is involved in the pathogenesis of the disease, corticosteroid hormones are quite effective in certain cases.