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Differential diagnosis of purpura

Table of contents
Differential diagnosis of purpura
Purpura at Verlgof's illness
Not Werlhof's disease
The most frequent reasons of purpura

The term "purpura" is applied to designation capillary hemorrhages which arise spontaneously or under the influence of insignificant injuries.
Dot hemorrhages (petechias) and bruises (ecchymomas) usually are located in skin and a mucous membrane. They considerably differ from each other in size. Merging, they can form quite extensive bruises with fancy borders. Bleeding from capillaries of a mucous membrane in a cavity of an organism and in external environment sometimes appears the only manifestation of a syndrome. Others nasal bleedings and odontorrhagias meet more often. The purpura in other bodies meets seldom.

Damage of a wall of a capillary to an organism of the healthy person is followed by activation of the protective mechanism of a hemostasis. Platelets accumulate in the place of defect of epithelial fabric. In interaction with collagen of adjacent connecting fabric in plates serotonin and adenosinediphosphate under the influence of which they stick together in the unit, rykhlo an occluding gleam of a capillary are formed. These primary blood clots almost completely consist of plates with insignificant impurity of erythrocytes. Along with the described process in the vicinity of the damaged capillary fabric thromboplastin under the influence of which between separate plates in the unit a small amount of thrombin is formed is released. The friable unit from plates under the influence of thrombin is reduced, densely corking anatomic defect of a capillary.
Blood coagulation mechanisms, though take part in interaction of platelets with a wall of the damaged capillary, do not exert decisive impact on a course of the processes described above which set often is called the mechanism of primary hemostasis or, figuratively, "a haemo static nail". Disturbance of this mechanism is the cornerstone of clinical manifestations of purpura.
In practical work need to distinguish purpura from the hemorrhagic diathesis developing owing to disturbance of mechanisms of blood coagulation is constantly felt.
Complexity of a pathogeny of purpura, i.e. existence of diseases at which simultaneous defeat of both primary hemostasis, and processes of blood coagulation is found does clear why exact diagnosis of separate clinical forms of hemorrhagic diathesis can be carried out only in big hematologic laboratories. The clinical experience which is saved up so far in most cases allows to distinguish nevertheless the main types of hemorrhagic diathesis from each other still before all difficult laboratory researches are made.

The purpura is shown usually by petechias and ecchymomas which arise at before healthy person as if spontaneously, out of communication with the previous injury. Its emergence is preceded sometimes by an acute infectious disease or reception of some drugs. In many cases of purpura it is possible to establish its connection with other diseases. Beginning as an acute disease, the purpura in many cases later some term spontaneously disappears. Sometimes it accepts a chronic current with the periods of an aggravation and remissions. Bleeding, as a rule, does not occur among relatives of the patient with purpura.
The raised bleeding caused by disturbance of blood coagulation differs from purpura in the fact that it in most cases is found since the childhood and keeps during all life of the patient. Bleedings arise, as a rule, after more or less expressed injury. Sometimes it is possible to reveal that the patient's relatives have similar bleedings.
Disturbances of blood coagulation are shown by usually deep hematomas, a hemarthrosis or extensive intramuscular hemorrhages. Petechias and ecchymomas at purpura affect only skin and mucous membranes. A hemarthrosis at purpura is not observed. Some value has also the fact that the purpura meets at women more often, and coagulation disturbances — at men.
Bleeding after extraction of tooth or a tonsilectomy at patients with disturbance of coagulability of blood can proceed 2 — 3 days. Repeated developing of the stopped bleeding is especially characteristic. At purpura neither long bleedings, nor resuming of already stopped bleeding are observed. Petechias and ecchymomas at purpura are usually more numerous in places of pressure upon skin a belt, garters, braces. Such natural distribution of hemorrhages at disturbances of blood coagulation is not observed.
Women with especially gentle skin, mainly blondes, during vaguely long time suffer from ecchymomas which easily appear and disappear, is especially frequent on the lower extremities. When results of clinical trial do not give a certain answer, additional methods of research can give some help. It is easy to carry out the simplest of them at the patient's bed.
Bleeding from an ear lobe after a prick its needle of Frank with the stylet nominated on 4 mm at the healthy person proceeds about 4 min. It is considered to be that at coagulation disturbances it remains without changes, and at purpura it is considerably extended. Unfortunately, this rule not always comes true. Abnormally long bleeding was observed by Leithold, Friedman (1969) only 2/3 patients with the purpura caused by dysfunction of platelets and only at 1/2 observed patients with syndromes have purpuras of other origin. Compression of a shoulder within 5 min. a cuff of the device of Reeve-Rochchi under pressure above diastolic and gives systolic at the healthy person to emergence only of single petechias in forearm skin below. It is considered to be that results of this test at purpura always are positive, however the number of petechias was sharply increased only at 13% of the inspected patients. From the provided data there is obvious a limited diagnostic value of simple auxiliary methods of research.
The judgment of nature of defeat of vessels at a bed of the patient will be more exact if to base it not on results of determination of duration of bleeding and fragility of capillaries, and on result of physical research and inquiry.
There are expressed distinctions in the frequency and the reasons of purpura in children's and therapeutic departments. In therapeutic department for adults of purple meets considerably less than in nurseries. It in most cases (appendix) are the reasons anatomic and toxic damage of marrow. Myeloproliferative syndromes are on the first place. Especially often we had to meet purpura as with the first clinical display of myeloproliferative leukemia. Infiltration of marrow tumors or their metastasises was one of the frequent reasons of purpura too.
The purpura arising owing to toxic influences on marrow of infectious diseases and medicines occurs at adults less than purpura owing to anatomic damage of marrow. The purpura in these cases is only one of syndromes of the general illness and seldom dominates in her picture. The purpura of not clear etiology (thrombocytopenic, or so-called simple) occurs at adults quite seldom.
The purpura can be recognized only idiopathic after an exception as more frequent, and its more rare reasons. The number of the last is very great. Simple transfer does not facilitate difficulties of their identification.
The purpura meets more often in combination with thrombocytopenia therefore definition of number of thrombocytes is the first diagnostic action at this syndrome. Depending on results of research all purpuras can be shared into thrombocytopenic and vascular (not thrombocytopenic).
Werlhof's disease
In 1 mkl blood of the healthy person 2 contain • 105 — 3105 thrombocytes. The purpura arises usually in that case when the number of thrombocytes becomes lower than 5 • 104 in 1 mkl blood. The purpura can sometimes be absent when falling number of thrombocytes to 2 • 104 and even to 1 • 104 in 1 mkl blood.

Thrombocytopenia develops owing to an insufficient thrombocytopoiesis or owing to the accelerated destruction of thrombocytes in the patient's organism more often. Other reasons of thrombocytopenia in therapeutic departments meet rather infrequently.
The division of the reasons of thrombocytopenia provided in the appendix is considerably artificial as at the same patient thrombocytopenia can have a complex origin. For example, the Werlhof's disease at metastasises of cancer can be a consequence not only simple reduction of the number of megakarioshchgt which came under the influence of a marrow infiltration tumor cells, but also a consequence of the autoimmune lysis of thrombocytes developing in parallel. Results of a sternal puncture, and even better results of a trepanobiopsiya in cases of this sort will show value of the first of the mentioned factors, showing at the same time practical expediency of all classification.
The purpura owing to insufficiency of a thrombocytopoiesis is often observed at a myeloid metaplasia of marrow, at metastasises of tumors in marrow, at a multiple myeloma and a myelofibrosis. The radiation exposure and some chemotherapeutic means which are applied to treatment of new growths and some other diseases sometimes suppress function of all sprouts of marrow, and sometimes lead to preferential or selective defeat of megacaryocytes. Trombotsptopeniya in the last cases represents the most precursory symptom of their myelotoxic action. The lack of a thrombocytopoiesis can meet in combination with a hypoplasia of erythrocyte and myeloid sprouts of marrow (for example, at Fankoni's syndrome, hypoplastic anemia, a vitamin deficiency of B12, folic acid, an azotemia). Inborn insufficiency of megacaryocytes in marrow meets is exclusively rare and always in combination with other anomalies of development.
Trepanobiopsiya or sternal puncture allow to establish connection of a Werlhof's disease with a condition of a marrowy hemopoiesis. Disturbances of a thrombocytosis prove disappearance or reduction of megacaryocytes in marrow punctate. Also others have not smaller diagnostic value specific to each of the listed diseases of change of marrow. The normality of a marrowy hemopoiesis specifies that reduction of number of platelets came, obviously, owing to their destruction out of marrow.
Believe that platelets take part in immunological reactions, adsorbing complexes of some antigens on the membrane. Injection gamma globulinovoy the fraction of blood taken from the patient with a Werlhof's disease quite often is followed by the expressed reduction of number of thrombocytes in blood of the healthy recipient. On the basis of these factors the assumption of possible communication medicinal and some other cases of a Werlhof's disease with immunologic mechanisms was made.

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