bubble_chart Overview

Primary pulmonary tuberculous focus (primary tuberculosis) is the lesion that occurs in the lungs when a child is first infected with tubercle bacilli. Since the body lacks immunity and hypersensitivity to tubercle bacilli at this stage, the infection often spreads to local lymph nodes. When both the pulmonary lesion and the enlarged local lymph nodes are present, it is called the primary complex. Its characteristics include: the primary lesion is usually located at the base of the upper lobe or the upper part of the lower lobe, often near the periphery, more frequently on the right side than the left, with a size of about 1–2 cm, though some infants may present with large patchy lesions. Approximately 4/5 of affected children have only one lesion, and the involved lymph nodes are mostly on the same side, ranging in size from tumor-like masses to those too small to detect. The nature of the lesion is primarily exudative or caseous necrosis.

bubble_chart Clinical Manifestations

1. Subcutaneous node (infection): Toxic symptoms include poor mental state and appetite, physical weakness prone to upper respiratory infections, failure to gain weight, emaciation, night sweats, and restless sleep. Typical cases present with long-term chronic low-grade fever, but infants may have an acute onset with higher fever and a shorter course. Generalized lymphadenopathy is common.
2. Subcutaneous node allergic symptoms: May present with skin erythema nodosum, herpetic conjunctivitis, and subcutaneous nodular Bi disease (transient polyarthritis).
3. Respiratory symptoms: Mostly manifest as a dry cough. If lymphadenopathy compresses the bronchi, it may lead to a whooping cough-like spasmodic cough. Hemoptysis is less common in children than in adults; positive lung signs are fewer than the lesions seen on chest X-ray.

Other medical history

1. Subcutaneous node contact history is of significant diagnostic value for subcutaneous node disease and should be carefully inquired about.
2. BCG vaccination history: BCG is an attenuated live subcutaneous node vaccine. Vaccination can confer immunity against subcutaneous node disease and plays an important role in prevention. If the patient has not been vaccinated with BCG or the vaccination was unsuccessful (no BCG scar at the deltoid muscle insertion site), this can also aid in diagnosing subcutaneous node disease.
3. Epidemic disease history: Conditions such as measles or whooping cough may lower the child's immunity and increase susceptibility to infection.

Subcutaneous node (OT or PPD) test: The OT test should start with a "small OT." If there is no reaction, proceed to a "medium OT" and then a "large OT." The significance of the test results should be interpreted in conjunction with the child's age and previous BCG vaccination history. A positive reaction supports the diagnosis of subcutaneous node disease, but a negative result does not rule it out (subcutaneous node test).

X-ray examination: Fluoroscopy or radiography, with tomography if necessary.

bubble_chart Auxiliary Examination

1. An elevated erythrocyte sedimentation rate (ESR) suggests active sexually transmitted disease changes, but there may also be significant subcutaneous node lesions with a normal ESR.
2. Sputum, gastric juice, or gastric lavage fluid can be examined for subcutaneous node bacteria. Infants cannot expectorate sputum and instead swallow it into the stomach. Direct smears of sputum or gastric lavage fluid can be stained for acid-fast bacilli to detect subcutaneous node bacteria or used for animal inoculation.
3. White blood cell count: During the active phase of the disease, the total white blood cell count is slightly increased, with a left shift in neutrophils and a decrease in lymphocytes. During the convalescence stage, when the lesions are resolving, the total white blood cell count returns to normal, the proportion of lymphocytes increases, and eosinophils may slightly increase.

bubble_chart Treatment Measures

(1) General Therapy

Pay attention to nutrition and strengthen rest. Asymptomatic individuals may take medication and attend school but should be exempt from physical education and labor. They should be isolated from the source of pestilence to avoid deterioration and prevent acute pestilence disease.

(2) Anti-subcutaneous node Drugs

The principles of medication are: early, regular, full-course, combined, and appropriate dosage.

1. For primary pulmonary subcutaneous node with no symptoms or mild symptoms
   1. Single use of isoniazid (INH): 10–15 mg/(kg·d), infants and young children may be given 15–20 mg/(kg·d), with a maximum dose not exceeding 400 mg/d. The full daily dose should be administered in one draught on an empty stomach in the morning to achieve a high serum drug concentration for bactericidal effect, which is more effective than divided doses. For doses above 300 mg/d, take 30 mg of vitamin simultaneously to prevent peripheral neuritis. The treatment course lasts 12–18 months.
   2. To delay drug resistance, the following may be used:
      1. INH (dose as above) + ethambutol (EMB) 25 mg/(kg·d), adjusted to 15 mg/(kg·d) after 4–6 weeks, with a treatment course of 6–12 months. The main side effect of EMB is visual impairment (retrobulbar neuritis), so it is suitable for older children and can gradually recover after discontinuation.
      2. INH (dose as above) + sodium para-aminosalicylate (PAS) 150–300 mg/(kg·d), with a maximum daily total dose not exceeding 8 g, divided into three doses taken half an hour after meals, with the last dose doubled. The treatment course is 6–12 months;
      3. INH (dose as above) + thioacetazone (TB1) 2–3 mg/(kg·d). The treatment course is 6–12 months.
2. For primary pulmonary subcutaneous node with active symptoms
   1. INH (dose as above) + streptomycin (SM) 20 mg/(kg·d), with a maximum dose of 0.75 g/d (some advocate a maximum dose of 0.6 g/d for children), divided into 1–2 intramuscular injections daily for 4 weeks. Pay attention to auditory nerve damage; if tinnitus or vertigo occurs, discontinue the drug promptly to avoid irreversible deafness.
   2. INH (dose as above) + SM: If no toxic reaction occurs after 4 weeks, SM may be administered every other day from weeks 4–8 at the original dose, and twice weekly from weeks 8–12, for a total of 12 weeks. Alternatively, after stopping streptomycin, add one of EMB, PAS, or TB1, for a total of 6–12 months. The total course of EVH is 18 months.
   3. INH (dose as above) + rifampicin (RFP) 10 mg/(kg·d) for 3–6 months, followed by INH alone for 12–18 months. Monitor for liver function damage during medication.
   4. INH (dose as above) + ethionamide (ETH): The dose is 10 mg/(kg·d), followed by INH alone for 12–18 months after 3–6 months.
   Drug-resistant strains to SM and INH are more sensitive to ETH, but thisYaoduihas significant gastrointestinal irritation, which may be difficult for children to tolerate, and may cause mental depression, drowsiness, and weakness. About 5% of patients develop hepatitis (liver damage), which can recover after discontinuation. Taking vitamin B1 and complex vitamin B can alleviate drug reactions. Taking the medication after meals and adding antacids can reduce gastrointestinal irritation.

bubble_chart Prevention

(1) BCG vaccination

Initial vaccination within 3 days after birth, revaccination at 5-6 years old. OT test should be performed before revaccination, and no further vaccination is required for those already infected with subcutaneous node.

(2) Drug prevention

1. For those who have close contact with open subcutaneous node, regardless of age, INH 5-10mg/(kg·d) should be given for 3-6 months.<
2. For infants and young children who have not been vaccinated with BCG, or whose OT or PPD test is positive, or whose OT or PPD test exceeds "++" after BCG vaccination, INH 10mg/(kg·d) should be given for 6 months.
3. For children whose OT or PPD test changes from negative to positive, the same as 2.
4. For children with subcutaneous node poisoning symptoms, positive OT or PPD test, and no specific lesion found, INH 10mg/(kg·d) should be given for 6-12 months.
5. For infants and young children who have recently suffered from measles, whooping cough, or other pestilence diseases, and whose OT or PPD test remains positive, the same as 4.
6. For children who require long-term hormone therapy, such as nephrotic syndrome and leukemia, and whose OT or PPD test is positive (excluding the effect of BCG).

bubble_chart Differentiation

This disease should be differentiated from mycoplasma pneumonia. Mycoplasma pneumonia is more common in older children aged 5 to 15. In addition to moderate fever, symptoms of irritating cough are more prominent, and may be accompanied by sore throat, headache, substernal pain, joint pain, etc. There are few positive lung signs, but X-ray findings are variable, with shadows usually resolving within 2 weeks. The white blood cell count is normal or decreased, and the cold agglutination test is positive.