Metastatic involvement of the lungs
The most common cause of intraparenchymal solid malignant lesions in children is metastasis. The primary source is located outside the lungs. Wilms tumor and osteosarcoma metastasize to the lung tissue most frequently.
Lymphogenic metastases occur in 5–20% of patients. CT examination in such children requires special caution. Dependent (hypostatic) atelectasis, which develops in the posterobasal segments in the supine position, can mimic or completely obscure peripheral pulmonary nodules. To distinguish true metastasis from atelectasis, scanning in the prone (prone) or lateral decubitus (decubitus) position is recommended.
Primary malignant tumors
Primary lung tumors in children are extremely rare, with an incidence of only 0.05 per 100,000.
The most frequent solid neoplasms include:
- Pleuropulmonary blastoma (pleuropulmonary blastoma). It occurs in patients under 5 years of age. Three types are distinguished: cystic (Type I), mixed cystic-solid (Type II), and predominantly solid (Type III). Mixed types typically abut the pleura in the lower lobes. Large lesions can occupy an entire hemithorax, displacing mediastinal organs. They must be differentiated from congenital cystic adenomatoid malformations (CPAMs).
- Bronchogenic carcinoma (bronchogenic carcinoma). Arises in adolescence, accounting for about 17% of all primary pediatric malignant lung tumors. It is characterized by high aggressiveness and is often disseminated at the time of detection. Radiologically, it does not differ from carcinoma in adults.
- Inflammatory myofibroblastic tumor. Usually presents as a central endobronchial mass. Exhibits variable biological behavior.
Bronchial adenomas
Among bronchial adenomas, half of the cases are bronchial carcinoid tumors. In children, they rarely manifest with the classic carcinoid syndrome. Instead, pediatric carcinoids present with wheezing (wheezing), hemoptysis, or lobar collapse (atelectasis).
These tumors typically localize to the central airways. Conventional radiography often fails to show the mass itself, revealing only its complications, such as distal emphysema or lobar collapse of the lung.
Class and exam questions
What is the most common intraparenchymal lung tumor in children?
Most commonly, lung metastases from extrathoracic sources are found in the lungs of children, for example, in osteosarcoma or Wilms tumor.
Why change the child's body position during a CT scan for metastases?
Scanning in the prone or lateral position helps expand the posterobasal lung segments and differentiate true metastatic nodules from hypostatic atelectasis that occurs in the supine position.
At what age is pleuropulmonary blastoma typically diagnosed?
Pleuropulmonary blastoma is characteristic of children under 5 years of age.
What else to study on this topic
- Chest wall tumors in children (Ewing sarcoma, rhabdomyosarcoma)
- Differential diagnosis of mediastinal masses
- CT imaging of pulmonary infections in immunodeficiencies
- Radiological patterns in Langerhans cell histiocytosis
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