Nodular disease is a granulomatous disease of unknown origin. A “granuloma” is actually an inflammatory condition that can be understood as an “aggregate” of macrophages and lymphocytes. The lungs and intrathoracic lymph nodes are most often “involved”, accounting for more than 90% of cases.
When only the hilum (the central depression on the inner side of the lung from which the main bronchi, pulmonary arteries, pulmonary veins, and lymphatic vessels enter and exit) or mediastinal lymph nodes are involved, pulmonary nodular disease can be easily “confused” with lung cancer on imaging. However, pulmonary nodular disease also has “exclusive” features, and it is not difficult for doctors to make a correct diagnosis when they master these “signs”.
When only the hilum (the central depression on the inner side of the lung from which the main bronchi, pulmonary arteries, pulmonary veins, and lymphatic vessels enter and exit) or mediastinal lymph nodes are involved, pulmonary nodular disease can be easily “confused” with lung cancer on imaging. However, pulmonary nodular disease also has “exclusive” features, and it is not difficult for doctors to make a correct diagnosis when they master these “signs”.
- More common in young and middle-aged people, most of which heal on their own. In general, patients with pulmonary nodular disease are younger than those with lung cancer, are more likely to be young and middle-aged, have more insidious symptoms, are more likely to have recurrent episodes, and a significant number of patients have the potential to heal on their own. In other words, without specific treatment, enlarged nodal lesions can shrink. This is distinctly different from the biological characteristics of lung cancer.
- “Epiphenomenal”. The clinical symptoms and chest radiographic features of pulmonary nodular disease are highly inconsistent. That is, the chest imaging has already shown significant changes (e.g., enlarged lymph nodes in the hilar region), but the patient’s clinical symptoms are relatively mild, such as cough, coughing, chest tightness, and malaise, and in a few cases, blood in the sputum. On a typical chest radiograph of nodular disease, bilateral symmetrical hilar lymph nodes can be seen to be significantly enlarged, potato-shaped, with relatively clear borders and uniform density; when the nodes invade the lung parenchyma, they may show diffuse reticular, reticulonodular, small nodular or lamellar shadows on both sides of the lung tissue, and later may develop into interstitial fibrosis (inflammatory disease of the interstitial lung), or even “honeycomb lung “.
- Extrapulmonary symptoms. Pulmonary nodular disease may manifest as ocular conjunctivitis, iridocyclitis, superficial lymph node enlargement, hepatosplenomegaly, polyarthritis, etc. if it involves extra-pulmonary tissues, or cardiac arrhythmia (disturbance of the heartbeat rhythm) if it involves the heart. If the physician suspects nodules, careful examination can reveal superficial lymph node enlargement, nodular protrusions and erythema around the skin and joints, etc.
- Other features. Nodular disease was also diagnosed earlier by the nodular disease antigen (Kveim) test. A 1:10 physiological saline suspension of lymph nodes or spleen tissue from patients with acute nodular disease was used as the antigen and injected subcutaneously to produce a local response; nodular disease granulomatous changes were also seen in pathological sections. However, its use is limited because there is no standard clinical antigen. In addition, serum angiotensin converting enzyme (SACE) activity is increased in patients with nodular disease, while tuberculin tests are mostly negative, which also helps in the diagnosis of nodular disease. Of course, lymph node biopsy provides the most accurate diagnosis.
- Thoracic imaging showing symmetrical enlargement of bilateral hilar and mediastinal lymph nodes with or without intrapulmonary grid, nodular or sheet-like shadows;
- Histologic biopsy with confirmed non-caseating necrotizing granuloma with negative antacid staining;
- Increased SACE activity.
The main diagnostic criteria that are more commonly accepted are.
In conclusion, the chest presentation of pulmonary nodulopathy is not clearly specific and requires a comprehensive analysis of various imaging manifestations and clinical data such as symptoms, signs, laboratory tests, and histological biopsy if necessary. Correct identification of these exclusive features can help doctors to distinguish nodal disease from lung cancer.
Co-reviewed by: Guangdong Provincial People’s Hospital Guangdong Lung Cancer Institute Dr. Wang Zhen, Deputy Chief Physician Dr. Kai Yin