What Is Thymic Hypoplasia?

Thyroid hypoplasia is also known as congenital thymic hypoplasia, also known as DiGeorge abnormality or III and IV pharyngeal sac syndrome. Can be characterized by autosomal dominant or recessive inheritance. ^[1]

Thymic hypoplasia

Basic overview of thymic hypoplasia

Etiology and pathogenesis of thymic hypoplasia

The disease is a disease of T cell function deficiency caused by congenital dysplasia or dysplasia, and cell-mediated immune deficiency or suppression. Can be divided into two types of complete and partial. The degree of immune deficiency can range from a slight defect in the thymus with spontaneous normalization of T cell function, to a deficiency in the function of the thymus, which severely affects B cell function. Although immunoglobulin levels are usually normal, viral or fungal infections are very common. Because the thymus and parathyroid glands are developed from the 3rd and 4th pharyngeal arches, they are also accompanied by hypoparathyroidism and sometimes congenital defects of the aortic arch and heart. ^[1]

Clinical manifestations of thymic hypoplasia

The clinical features are neonatal hand-foot convulsions, with special features: low-ear deformities with notches, too small jaws, short and short distances between people. Candida and other fungal infections and severe viral infections occur repeatedly, but bacterial infections are not serious. The syndrome includes congenital absence of parathyroid and thymus and abnormal aortic arch. Hypocalcemia caused by neonatal hand-foot convulsions is usually the first manifestation of the disease. Defects in the aortic arch and heart are the most common causes of death. ^[1]

Auxiliary examination of thymic hypoplasia

The children's serum immunoglobulin levels were normal and the antibody response ability was basically normal or slightly lower than normal. The cellular immune function is very poor, the number of peripheral blood lymphocytes is low, the absolute count is <1.5 × 10 / L, mainly because the number of T cells is significantly reduced, the rate of E rosette cell formation is <10%, and the T cell function test is "no response". ^[1]

Diagnostic criteria for thymic hypoplasia

When hypocalcemia is difficult to correct in neonates, the face and heart should be carefully checked. If there are abnormalities, especially when X-ray examination does not show thymus shadow, this diagnosis is supported. In mild cases of hypocalcemia, it is often suspected after congenital heart disease or right aortic arch is found. ^[1]

Treatment of thymic hypoplasia

Thymic transplantation is successful and there is a real possibility of self-healing. Thymic hormone may play an important role in the immune reconstruction of this disease, the dose is 1 ~ 250mg / m intramuscularly or subcutaneously, once / d for a total of 1 ~ 3 weeks, and then changed to once every 1 ~ 2 weeks. ^[1]