Abstract
Intrapulmonary lymph nodes (IPLNs) represent subpleural lymphoid structures in the lung parenchima with all histological signs of a typical lymph node. They are responsible for up to 45% nodules detected by chest CT. Since the number of studies are on the grow, physicians will come across these structures more and more often, including within the lung cancer screening programmes. Hence, it is important to correctly differentiate intrapulmonary lymph nodes from potentially malignant foci. The review considers the background of intrapulmonary lymph nodes’ studies and the establishment of IPLNs radiological concept, that has very clear criteria. From the radiologists’ point of view, only non-calcified solid type nodules, with clear boundaries, oval in shape in 3 orthogonal planes and lenticular in 2, not exceeding 12mm in diameter, not connected with any vessels, and located up to 15mm from visceral pleura, may be attributed to intrapulmonary lymph nodes. The nodules located on the pleura are to be polygonal or lenticular in shape in 2 orthogonal planes. The terminological discord should be mentioned here, when some morphologists attribute IASLS group 11–14 lymph nodes to intraparenchymal ones, while others attribute them to bronchopulmonary (hilar) ones. This is key when assessing the possibility of metastatic process into intrapulmonary lymph nodes. Various publications state high frequency of metastasis into 11–14 group of lymph nodes in non-small cell lung cancer, while subpleural intrapulmonary lymph nodes are not a target for metastasis. Тhus, in order to avoid hyperdiagnostics and prescribing inadequate management to patients, the issue of correct interpretation of the pulmonary nodules as intrapulmonary lymph nodes demands special attention.