Pediatric essential thrombocythemia

Introduction to children with essential thrombocytosis Idiopathic or primary thrombocytosis (ET), also known as hemorrhagic thrombocytosis, is a myeloproliferative disorder characterized by proliferation of megakaryocyte lines, clinically with hemorrhage, thrombosis and persistent platelets. Increased, characterized by mild hyperplasia of other hematopoietic cell lines. Clinically, the number of platelets with unknown causes continues to increase, >1000×109/L. After excluding other myeloproliferative diseases, the disease can be considered. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: abdominal pain

Causes of childhood essential thrombocytosis

(1) Causes of the disease

The cause is unknown, and the platelet count is more than twice the standard deviation (±2SD) of the mean value. It is called thrombocytosis.

Usually, one third of the body's platelets are retained in the spleen, and patients with surgically removed spleen or functional spleen are missing. Although the total number of platelets in the whole body tends to be normal, the platelet count can be increased, so for patients with such spleen deficiency, platelets are present. The increase in count is normal and no treatment is needed. Similarly, if adrenaline is injected, the platelets in the body can be mobilized from the spleen into the blood to maintain a transient platelet rise, and the platelet count is spontaneous. Pseudo-elevation can also be caused by the presence of globular cells, Pappenheim bodies, red blood cells and white blood cell debris, or bacteria.

The causes of true thrombocytosis can be divided into two categories: primary thrombocytosis and reactive (or secondary) thrombocytosis. In primary thrombocytopenia, platelet production does not respond to normal regulatory mechanisms and does not occur in Under normal circumstances, due to the increase of megakaryocytes caused by thrombocytosis, in childhood, thrombocytosis is mainly secondary factors, usually, the degree of reactive thrombocytosis is mild, asymptomatic, can be restored after treatment of the primary disease, Reactive thrombocytosis is accompanied by an increase in megakaryocytes. The degree of increase is parallel with the degree of activity of the primary cause, and often coincides with inflammatory conditions. For example, iron deficiency is often associated with increased platelet count for 1 to 2 weeks. Mild thrombocytosis is often secondary to severe trauma and surgery, and treatment for thrombocytosis is not necessary.

Children with thrombocytopenia rarely develop primary myeloproliferative diseases such as primary thrombocytosis or chronic myeloid leukemia.

(two) pathogenesis

1. Crohn's disease: The disease is currently considered to be a clonal disease of pluripotent hematopoietic stem cells, according to the following:

(1) and bone marrow hyperplasia syndrome can be transformed: this disease is closely related to chronic myeloid leukemia, polycythemia vera, myelofibrosis and erythroleukemia, which can be called myeloproliferative syndrome, which can transform each other. Therefore, it is considered to be a different stage of the same disease, and its mechanism may be malignant changes at the level of pluripotent stem cells differentiated into erythroid, granulocyte, megakaryoblast and fibroblast lines, resulting in malignancy of single or multiple cell lines. Proliferation, only when different myeloproliferative syndromes, the main proliferating cell series are different, and some patients can eventually develop acute myeloid leukemia.

(2) It has the same kind of isozyme: G6PD isoenzyme is used as a marker of cloning. The red blood cells, neutrophils and platelets of this patient have the same isozyme, so the disease is considered to be more Krone disease of stem cells.

(3) Continuous increase of platelets: This disease not only has the proliferation of megakaryocyte cell line with persistent bone marrow, but also the characteristics of extramedullary infiltration. In the liver, spleen and other tissues, the proliferation of megakaryocyte cell line appears, and the platelet production rate of bone marrow Can be increased by 6 times, plus extramedullary tissue hyperplasia, platelets released by the storage pool into the blood circulation, normal platelet life, leading to extreme increase in peripheral platelet persistence, platelet function is often abnormal.

2. Mechanism of thrombosis: Due to the obvious increase of platelets, and abnormal function, coupled with the presence of vascular lesions, extremely increased platelets are prone to thrombosis. Activated platelets can produce TXA2 to cause platelet aggregation and release, forming microvascular thrombosis.

3. Mechanism of bleeding: rupture of thromboembolic area, abnormal platelet function, in addition, thrombosis consumes excessive clotting factors, causing coagulopathy, resulting in clinical bleeding.

Prevention of primary thrombocytopenia in children

Because the cause is not clear, there are no precise preventive measures for primary thrombocytosis.

Pediatric essential thrombocytopenia complications Complications, abdominal pain

Erythematous limb pain: After embolization of the lower extremity, it can show numbness, pain, and even gangrene. Intermittent limp. Mesenteric vascular thrombosis can cause vomiting and abdominal pain.

Symptoms of childhood essential thrombocytosis common symptoms skin pale fatigue nausea limbs cold abdominal pain gum bleeding thrombocytopenia intermittent sputum nasal bleeding dry gangrene

The onset is slow, mostly for months to years, 20% of patients are asymptomatic, 80% may have dizziness, fatigue, but also because of postoperative bleeding or splenomegaly found, bleeding symptoms with nosebleeds, gum bleeding and digestion Road bleeding is more common, skin may have ecchymoses, a few have urinary tract, respiratory tract bleeding, occasional cerebral hemorrhage death, about 1/3 of patients have venous or arterial thrombosis, more common in limbs, may have cold extremities , afraid of cold, numbness, soreness, and then intermittent claudication, and finally developed into resting pain, night pain, local skin color is purple or pale, skin temperature is reduced, dry skin, dry toe of phalanx, venous thrombosis of extremities Shallow, red, swollen, high skin temperature, pain, tenderness, local pain of deep vein thrombosis, deep blood vessels can touch the cord; thrombus limb swelling, bruising, low skin temperature, venous gangrene, liver can occur, Spleen, mesenteric thrombosis caused abdominal pain, nausea, vomiting, 80% of patients with splenomegaly, 20% of patients may have asymptomatic spleen infarction and spleen atrophy, about 40% of patients have hepatomegaly, lungs, brain and kidneys can also embolize.

Examination of children with essential thrombocytosis

1. Blood test:

(1) Platelets: Platelets are significantly increased, most of them are larger than 1000×109/L. Because the number is too high, the counting is not accurate. Some people advocate that the height of the platelet layer is measured by the integrated tube, that is, the so-called platelet ratio, which can often reflect the platelets. The change, the platelet morphology in the blood plate is significantly mutated, and the giant deformed platelets are more common.

(2) white blood cells: white blood cell count is often increased, 95% of cases above 10.0 × 109 / L, up to 60.0 × 109 / L, mainly due to neutral polymorphonuclear neutrophils, a small amount in the blood film, late In young cells, 10% of patients had a decrease in phosphatase score and serum vitamin B12 concentration in the neutrophils, which increased by 25%, and the remaining 70% were normal.

(3) Red blood cells: There may be different degrees of anemia in a certain stage of the disease, generally small cells or normal cells with low pigmentation, which is related to blood loss, so hypochromic anemia, neutrophils, and platelets are extremely elevated. It makes sense to diagnose this disease.

2. Bone marrow: Hyperplasia is markedly active, with megakaryocyte proliferation, primordial and immature megakaryocytes, and platelets piled up.

3. Decreased platelet function: platelet adhesion, aggregation, release function is reduced, bleeding time is prolonged, blood clot retraction is poor, prothrombin time and thromboplastin production time are prolonged, platelet factor-III activity is weakened, and effectiveness is reduced.

4. Capillary fragility test: The capillary fragility test was selected as needed, and the result was positive.

5. Regular chest X-ray, B-ultrasound, angiography, CT and other examinations.

Diagnosis and diagnosis of primary thrombocytosis in children

Diagnostic criteria:

1. There are symptoms and signs of bleeding, embolism and splenomegaly.

2. Platelet count>1000×10 ⁹ /L, platelets piled up in blood samples, and there are huge platelets.

3. Myeloproliferation is active or extremely active, with enlarged megakaryocytes, large volume, and abundant cytoplasm.

4. White blood cell count and neutrophil increase.

5. The aggregation reaction of platelet adrenaline and collagen can be reduced.

6. Exclude secondary thrombocytosis and other myeloproliferative diseases.

Identification with secondary thrombocytosis, polycythemia vera, myelofibrosis, malignancy, and erythroleukemia.

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