What is the cause of mediastinal (mediastinum) adenopathy (lymph node enlargement)?

From the Guidelines

Mediastinal adenopathy is a condition that requires thorough evaluation, and the initial approach should include a comprehensive history, physical examination, and chest imaging, with a short-axis size threshold of 15 mm guiding the decision process, as recommended by the American College of Radiology 1. When evaluating mediastinal adenopathy, it is essential to consider the size, texture, and distribution of the lymph nodes, as well as the presence of any symptoms or underlying conditions. The American College of Radiology suggests that lymph nodes greater than 1 cm in short axis are more likely to be associated with malignant or granulomatous diseases, while those less than 15 mm are often reactive or benign 1. The management of mediastinal adenopathy depends on the underlying cause, which can range from infections such as tuberculosis or histoplasmosis, to malignancies like lymphoma or lung cancer, to inflammatory conditions like sarcoidosis. In asymptomatic patients with bilateral hilar lymphadenopathy, the American Thoracic Society suggests that sampling lymph nodes may not be necessary, as the majority of cases are due to sarcoidosis 1. In terms of imaging, CT scans with contrast are often the initial imaging modality of choice, with PET/CT or MRI used in certain cases to further characterize the lesion or guide biopsy. The American College of Radiology recommends a stepwise approach to imaging, with CT scans followed by PET/CT or MRI as needed, and diagnostic intervention such as biopsy or surgery reserved for cases where the diagnosis is uncertain or the lesion is suspicious for malignancy 1. Some key points to consider when evaluating mediastinal adenopathy include:

• The size and texture of the lymph nodes, with larger nodes more likely to be associated with malignant or granulomatous diseases
• The presence of any symptoms or underlying conditions, such as fever, weight loss, or exposure to infectious agents
• The distribution of the lymph nodes, with bilateral hilar lymphadenopathy often associated with sarcoidosis
• The use of imaging modalities such as CT, PET/CT, and MRI to further characterize the lesion and guide management
• The potential need for tissue sampling via biopsy or surgery to establish a definitive diagnosis.

From the Research

Media Style Adenopathy

• Media style adenopathy refers to the enlargement of lymph nodes in the mediastinum, which can be caused by various benign and malignant conditions 2.
• The diagnosis of mediastinal lymphadenopathy involves a combination of clinical, radiological, and pathological findings, with endosonographic modalities such as EBUS-TBNA, EUS-FNA, and EUS-B-FNA emerging as the cornerstone of diagnosis 2.
• Lymphadenopathy can also be classified as localized or generalized, with localized adenopathy prompting a search for an adjacent precipitating lesion and an examination of other nodal areas to rule out generalized lymphadenopathy 3.
• Generalized adenopathy should always prompt further clinical investigation, and a node biopsy may be indicated in some cases, with excisional biopsy of the most abnormal node being the preferred method for diagnosis 3.

Causes of Lymphadenopathy

• Lymphoma is a common cause of lymphadenopathy, with approximately 82,000 new cases diagnosed annually in the US 4.
• Lymphoma typically presents as painless adenopathy, with systemic symptoms such as fever, unexplained weight loss, and night sweats occurring in more advanced stages of the disease 4.
• Other causes of lymphadenopathy include infections, granulomatous conditions, and malignancies such as lung cancer and extrathoracic cancer 2, 5.

Diagnosis and Treatment

• The diagnosis of lymphadenopathy involves a combination of clinical, radiological, and pathological findings, with imaging modalities such as computed tomography and positron emission tomography/computed tomography being used to stage the disease 2, 5.
• The treatment of lymphadenopathy depends on the underlying cause, with lymphoma being treated with chemotherapy, radiation therapy, or a combination of both 4.
• Transthoracic needle biopsy of mediastinal lymph nodes is a safe and accurate diagnostic staging procedure that can be used as an alternative to mediastinoscopy in patients with lymphadenopathy 5.