shotty subcentimeter bilateral paraaortic lymph nodes present

On CT, the preferred radiologic modality for visualizing lymph nodes, the normal mediastinal nodes are reniform soft tissue structures with a fatty hilum. Normal lymph nodes in the mediastinum typically measure less than 10 mm by short axis.

The organization of mediastinal lymph nodes is based upon their relation to surgical landmarks: great vessels, trachea/bronchi, and pleura.

Rapid growth can cause pain, while slow mitotic activity (often seen with cancer) results in painless lymphadenopathy. With immune cell activation, LNs grown as cells within the divide. T-lymphocytes sample antigens from pathogens and interact with B cells to initiate clonal expansion for antibody production. Along the way, nodes, like those found in the mediastinum, sample the lymph, filtering out potential threats and unwanted cellular debris before it re-enters the blood supply. Macrophages within the lymph nodes phagocytize these unwanted substances and then break them down for recycling by the body. The fluid and cells are transported back to the chest by the lymphatic vessels. Along with the normal macromolecules and lymphocytes within the plasma, dead cells and material that may be harmful to the body such as bacteria, viruses, and tumor cells also leak out, and in turn, enter the lymph. Unlike arteries and veins, lymphatics are blind-ending vessels that transport interstitial fluid, immune cells, and macromolecules, collectively called lymph, through LNs and back to the chest for return into the blood supply via the subclavian veins. Lymph originates when blood plasma leaks out of capillaries and into the interstitial space. The network of lymphatic vessels and LNs extends throughout the entire body to support the proper function of its immune system along with the absorption of dietary fats and fluid homeostasis. The IASLC Atlas supersedes all previous schema and reconciles discrepancies among older popular systems such as the Naruke lymph node classification and the Mountain-Dresler modified version of the American Thoracic Society lymph node map. The most current map of intrathoracic lymph nodes is the International Association for the Study of Lung Cancer (IASLC) map. Stations 1–9 correspond to mediastinal nodal groups, while stations 10–14 represent hilar and other more peripheral extra mediastinal nodal groups. In contrast to the functional subdivisions, intrathoracic LN locations have been traditionally mapped into 14 stations according to their relationship to landmarks encountered during mediastinoscopy and thoracotomy for lung cancer. Dividing the mediastinum helps to narrow down the lengthy differential diagnoses, which can present in the thorax (including, but not limited to: infections like tuberculosis, the nodal spread of lung cancer, sarcoidosis, lymphoma, silicosis, and asbestosis). Lymph nodes (LNs) are present in all three functional compartments of the mediastinum, though most lymphatic tissue is found in the anterior and middle compartments, and the etiology of lymphatic pathology varies by subdivision. These subdivisions are used to describe the locations of lesions, thereby helping to facilitate differential diagnoses and communication between providers.

The mediastinum is classically subdivided into three functional divisions: anterior (pre-vascular), middle (visceral), and posterior (paravertebral) mediastinum. The mediastinal compartment contains multiple critical organs and vessels and serves as the central hub for lymphatic drainage.

Shotty subcentimeter bilateral paraaortic lymph nodes present