It is common for people to be told that a “small nodule” has been found in their lungs during a medical examination. What is a nodule, how should it be treated, and what further steps should be taken?
Small nodular lesions in the lungs can be benign, such as inflammatory pseudotumors, malformations, tuberculosis spheres and hemangiomas, or malignant, such as primary lung cancer or metastatic cancer in the lungs. Some benign lesions may also transform into malignant after prolonged irritation. Due to the development of imaging technology, some lesions that were not possible to be detected before have been able to be revealed, providing assurance for early detection and early treatment of lung cancer. According to the statistics of a large sample of the population, more than half of the single small nodules in the lung with diameter greater than 1.0 cm are malignant. Therefore, in clinical practice, small intrapulmonary nodules found unintentionally during physical examination should never be taken lightly. Small intrapulmonary nodules usually refer to substantial intrapulmonary lesions less than 3.0 cm in diameter, which are common and difficult to diagnose in thoracic surgery and have been a clinical challenge. Its complex etiology and lack of specificity of clinical manifestations make it difficult to diagnose and prone to misdiagnosis and underdiagnosis.
Imaging differentiation of small intrapulmonary nodules includes.
1. Site: Nodules in the anterior segment of the upper lobes of both lungs, the lingual segment of the upper lobe of the left lung and the middle lobe of the right lung are mostly inflammatory lesions or tumors, especially lung cancer. The posterior segment of the upper lobe tip and the dorsal segment of the lower lobe are mostly benign lesions, especially tuberculosis foci.
2.Size: nodules less than 5.0mm are more likely to be benign; nodules of 5.0mm-10.0mm should be followed up closely; malignant tumors account for more than 50% of nodules of 10.0mm-30.0mm, and the larger the nodule, the higher the possibility of lung cancer.
3. Morphology: those with shallow lobes, short and thin burrs and pleural depression signs suggest lung cancer; those with smooth edges and coarse, long and sparse burrs suggest benign. But sometimes it is difficult to distinguish.
4.Degree: Nodules with uneven density, small vesicles and tubules, small nodule accumulation, eccentric small cavities, and sparse calcification are mostly malignant; those with uniform density are mostly benign.
5, surrounding: surrounding lung tissues showing inflammation, emphysema, dysplasia, infiltration and thickening of bronchial vascular bundles are mostly malignant nodules; while satellite foci, “halo”, etc. are mostly suggestive of benign nodules.
6.Enhancement: Enhanced CT shows uneven enhancement or moderate enhancement is mostly malignant; non-enhancement or high enhancement is mostly seen in benign nodules.
Differentiation from disease classification.
1, tuberculoma: uneven density, may have calcification and cavity, no enhancement after contrast injection, with pleural adhesion band.
2.Inflammatory pseudotumor: mostly with a history of infection or inflammatory sequelae, uniform density, and rare calcification.
3, mycobacterial ball: often parasitic in the tuberculosis cavity, uneven density, may have calcification, visible halo sign and satellite foci, “air crescent sign” as the basis for diagnosis.
4, arteriovenous fistula: lesion enhancement is synchronized with large blood vessels, equal enhancement.
5, sclerosing hemangioma: spherical or round-like mass with smooth edges, can be significantly enhanced, or connected with intrapulmonary vascular shadow.
6, misshapen tumor: mostly below 2.0 cm, with smooth edges, may have lobes, uniform density or homogeneity, and can be diagnosed when fatty density or “popcorn”-like changes are detected within it.
7.Adenoma: low grade malignant tumor, round or round-like, mostly located in the periphery of the lung or in the trachea or bronchus, with smooth margins, uniform density, no calcified satellite foci, moderate enhancement, uniform strengthening.
8, metastases: single or multiple, varying in size, clear or blurred margins, uniform density, relatively common in the lung field zone or subpleural.
9, spherical pneumonia: large lesions, fuzzy margins in an invasive pattern, uneven density but not dense, and disparity in size of lesions in the lung and mediastinal windows are its characteristics.
For small nodules of unknown etiology, physicians and patients should not take them lightly. Regular follow-up is necessary, and sometimes the benefit of early surgical resection is greater than waiting. In general, CT review is recommended every 6 months for small intrapulmonary nodules less than 5.0 mm in diameter; every 3 months for nodules between 5.0 and 10.0 mm; and every month for nodules larger than 10.0 mm. In the latter two cases, our opinion is to perform intrapulmonary nodule excision biopsy more aggressively under minimally invasive thoracoscopy. If intrapulmonary nodules are found to grow faster or become irregular during follow-up, they often suggest malignant changes. Then surgical treatment is more appropriate. It should be clear that the 5-year survival rate (an important indicator of tumor prognosis) of early-stage lung cancer treatment can reach 70%-80%, while the advanced lung cancer are below 10%.
The following tests can be performed during observation: enhanced CT, lung puncture. If no abnormality is seen in any of the above examinations, CT can be repeated periodically for observation or direct surgical resection. In recent years, the mature development and popularity of thoracoscopic technology has become the best choice to solve this dilemma. For small intrapulmonary nodules, the diagnostic and therapeutic effect of transthoracoscopy can reach the level of traditional open-heart surgery, while avoiding unnecessary open-heart trauma, fundamentally changing the treatment strategy of small intrapulmonary nodular diseases.