Mediastinal lymphadenopathy or mediastinal adenopathy is an enlargement of the Mediastinal lymph nodes

Second most common primary anterior mediastinal mass in adults. Most are seen in the anterior compartment and rest are seen in middle compartment. Hodgkin's usually present in 40-50's with nodular sclerosing type (7), and non-Hodgkin's in all age groups. Can also be primary mediastinal B-cell lymphoma with exceptionally good prognosis. Common symptoms include fever, weight loss, night sweats, and compressive symptoms such as pain, dyspnea, wheezing, Superior vena cava syndrome, pleural effusions (10,11). Diagnosis usually by CT showing lobulated mass. Confirmation done by tissue biopsy of accompanying nodes if any, mediastinoscopy, mediastinotomy, or thoracotomy. FNA biopsy is usually not adequate. (12,13,14) Treatment of mediastinal Hodgkin's involves chemotherapy and/or radiation. 5 year survival is now around 75%. (15) Large-cell type may have somewhat better prognosis. Surgery is generally not performed because of invasive nature of tumor.

Of all cancers involving the same class of blood cell, 2% of cases are mediastinal large B cell lymphomas.

Most common primary anterior mediastinal tumor (20%) in adults but rarely seen in children. It can be classified as lymphocytic, epithelial, or spindle cell histologies, but the clinical significance of these classifications is controversial. Tonofibrils seen under electron microscopy can differentiate thymoma from other tumors such as carcinoid, Hodgkin's, and seminoma. Patients are usually asymptomatic but can present with myasthenia gravis-related symptoms, substernal pain, dyspnea, or cough. Invasive tumors can produce compression effects such as superior vena cava syndrome. (3,4) Thymomas are diagnosed with CT or MRI revealing a mass in anterior mediastinum. Therapy in stage I tumors consists of surgical resection with good prognosis. Stage II-III requires maximal resection possible followed by radiation. Stage IV disease requires addition of cisplatin-based chemotherapy in addition to those in stage II and III. For those with invasive thymoma, treatment is based on induction chemotherapy, surgical resection, and post-surgical radiation. 5-year survival for invasive thymoma is between 12-54% regardless of any myasthenia gravis symptoms (5,6).

Bilateral hilar lymphadenopathy is a bilateral enlargement of the lymph nodes of pulmonary hila. It is a radiographic term that describes the enlargement of mediastinal lymph nodes and is most commonly identified by a chest x-ray.

The following are causes of BHL:

- Sarcoidosis

- Infection

- Tuberculosis

- Fungal infection

- Mycoplasma

- Intestinal Lipodystrophy (Whipple's disease)

- Malignancy

- Lymphoma

- Carcinoma

- Mediastinal tumors

- Inorganic dust disease

- Silicosis

- Berylliosis

- Extrinsic allergic alveolitis

- Such as bird fancier's lung

- Less common causes also exist:

- Eosinophilic granulomatosis with polyangiitis

- Human immunodeficiency virus

- Extrinsic allergic alveolitis

- Adult-onset Still's disease

Lymph node enlargement is recognized as a common sign of infectious, autoimmune, or malignant disease. Examples may include:

- Reactive: acute infection ("e.g.," bacterial, or viral), or chronic infections (tuberculous lymphadenitis, cat-scratch disease).

- The most distinctive sign of bubonic plague is extreme swelling of one or more lymph nodes that bulge out of the skin as "buboes." The buboes often become necrotic and may even rupture.

- Infectious mononucleosis is an acute viral infection caused by Epstein-Barr virus and may be characterized by a marked enlargement of the cervical lymph nodes.

- It is also a sign of cutaneous anthrax and Human African trypanosomiasis

- Toxoplasmosis, a parasitic disease, gives a generalized lymphadenopathy ("Piringer-Kuchinka lymphadenopathy").

- Plasma cell variant of Castleman's disease - associated with HHV-8 infection and HIV infection

- Mesenteric lymphadenitis after viral systemic infection (particularly in the GALT in the appendix) can commonly present like appendicitis.

Less common infectious causes of lymphadenopathy may include bacterial infections such as cat scratch disease, tularemia, brucellosis, or prevotella.

- Tumoral:

- Primary: Hodgkin lymphoma and non-Hodgkin lymphoma give lymphadenopathy in all or a few lymph nodes.

- Secondary: metastasis, Virchow's Node, neuroblastoma, and chronic lymphocytic leukemia.

- Autoimmune: systemic lupus erythematosus and rheumatoid arthritis may have a generalized lymphadenopathy.

- Immunocompromised: AIDS. Generalized lymphadenopathy is an early sign of infection with human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). "Lymphadenopathy syndrome" has been used to describe the first symptomatic stage of HIV progression, preceding a diagnosis of AIDS.

- Bites from certain venomous snakes such as the pit viper

- Unknown: Kikuchi disease, progressive transformation of germinal centers, sarcoidosis, hyaline-vascular variant of Castleman's disease, Rosai-Dorfman disease, Kawasaki disease, Kimura disease

Axillary lymphadenopathy is lymphadenopathy of the axillary lymph nodes.

Lymph nodes or 'glands' or "nodes" or "lymphoid tissue" are nodular bodies located throughout the body but clustering in certain areas such as the armpit, back of the neck and the groin. They are part of the lymphatic system.

The lymphatic system is part of the body's immune surveillance system. Blood contains fluid and blood cells. The fluid, which may contain suspended foreign material such as bacteria and viruses, seeps through blood vessel walls into the tissues, where it bathes the body cells and exchanges substances with them. Some of this fluid is then taken up by lymphatic vessels and passed back to the heart, where it is again mixed with the blood. On its way the fluid passes through the lymph nodes. If nodes detect something foreign passing through them such as a bacterium or a cancer cell they will swell up. This is called "lymphadenopathy" or "swollen glands". Usually this is localised (for example an infected spot on the scalp will cause lymph nodes in the neck on that same side to swell up), but when it is in two or more regions, it is called "generalized lymphadenopathy".

Usually this is in response to a body-wide infectious disease such as influenza and will go away once the person has recovered, but sometimes it can persist long-term, even when there is no obvious cause of disease. This is then called "persistent generalized lymphadenopathy" (PGL).

"Widened mediastinum/mediastinal widening" is where the mediastinum has a width greater than 6 cm on an upright PA chest X-ray or 8 cm on supine AP chest film.

A widened mediastinum can be indicative of several pathologies:

- aortic aneurysm

- aortic dissection

- aortic unfolding

- aortic rupture

- hilar lymphadenopathy

- anthrax inhalation - a widened mediastinum was found in 7 of the first 10 victims infected by anthrax ("Bacillus anthracis") in 2001.

- esophageal rupture - presents usually with pneumomediastinum and pleural effusion. It is diagnosed with water-soluble swallowed contrast.

- mediastinal mass

- mediastinitis

- cardiac tamponade

- pericardial effusion

- thoracic vertebrae fractures in trauma patients.

Lymph nodes may become enlarged in malignant disease. This cervical lymphadenopathy may be reactive or metastatic. Alternatively, enlarged lymph nodes may represent a primary malignancy of the lymphatic system itself, such as lymphoma (both Hodgkin's and non-Hodgkin's), lymphocytic leukemia,

Metastatic lymph nodes are enlarged because tumor cells have detached from the primary tumor and started growing in the lymph node ("seeded"). Since cancer generally occurs more frequently in older people, this kind of lymphadenopathy is more common in older persons. Metastatic lymph nodes tend to feel hard and may be fixed to underlying tissues and may or may not be tender. Usually the lymph nodes that directly drain the area of the cancer are affected by the spread (e.g. Sometimes metastatic cervical lymph node is detected before the main cancer). In such cases, this discovery leads to a search for the primary malignancy, firstly in the nearby area with endoscopy, "blind" biopsies, and tonsillectomy on the side of the lymphadenopathy. If no tumor is found, then the rest of the body is examined, looking for lung cancer or other possible sites. If still no primary tumor is detected, the term "occult primary" is used.

In lymphoma, usually there are multiple enlarged nodes which feel rubbery to palpation.

- Rhabdomyosarcoma

- Neuroblastoma

Lymphadenopathy of the axillary lymph nodes can be defined as solid nodes measuring more than 15 mm without fatty hilum. Axillary lymph nodes may be normal up to 30 mm if consisting largely of fat.

Cervical lymphadenopathy refers to lymphadenopathy of the cervical lymph nodes (the glands in the neck). The term "lymphadenopathy" strictly speaking refers to disease of the lymph nodes, though it is often used to describe the enlargement of the lymph nodes. Similarly, the term "lymphadenitis" refers to inflammation of a lymph node, but often it is used as a synonym of lymphadenopathy.

Cervical lymphadenopathy is a sign or a symptom, not a diagnosis. The causes are varied, and may be inflammatory, degenerative, or neoplastic. In adults, healthy lymph nodes can be palpable (able to be felt), in the axilla, neck and groin. In children up to the age of 12 cervical nodes up to 1 cm in size may be palpable and this may not signify any disease. If nodes heal by resolution or scarring after being inflamed, they may remain palpable thereafter. In children, most palpable cervical lymphadenopathy is reactive or infective. In individuals over the age of 50, metastatic enlargement from cancers (most commonly squamous cell carcinomas) of the aerodigestive tract should be considered.

The mediastinum (from Medieval Latin "mediastinus", "midway") is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax. The mediastinum contains the heart and its vessels, the esophagus, trachea, phrenic and cardiac nerves, the thoracic duct, thymus and lymph nodes of the central chest.

Simple surgical excision is considered curative. Rare recurrences have been reported.

It is most commonly caused by:

- Oesophageal rupture, for example in Boerhaave syndrome

- Asthma or other conditions leading to alveolar rupture

- Bowel rupture, where air in the abdominal cavity tracts up into the chest.

It has also been associated with:

- "Mycoplasma pneumoniae" pneumonia

- obesity

It can be induced to assist thoracoscopic surgery. It can be caused by a pulmonary barotrauma resulting when a person moves to or from a higher pressure environment, such as when a SCUBA diver, a free-diver or an airplane passenger ascends or descends.

In rare cases, pneumomediastinum may also arise as a result of blunt chest trauma (e.g. car accidents, fights, over pressure of breathing apparatus), while still evolving in the same fashion as the spontaneous form.

Pneumomediastinum is most commonly seen in otherwise healthy young male patients and may not be prefaced by a relevant medical history of similar ailments.

Intranodal palisaded myofibroblastoma, abbreviated IPM, is a rare primary tumour of lymph nodes, that classically presents as an inguinal mass.

It afflicts predominantly males of middle age.

Mediastinal fibrosis most common cause is idiopathic mediastinal fibrosis; less commonly histoplasmosis tuberculosis or unknown. It is characterized by invasive, calcified fibrosis centered on lymph nodes that block major vessels and airways. In Europe, this disease is exceptionally rare. More cases are seen

in USA where the disease may often be associated with histoplasmosis.

To diagnose this condition, scans or other imaging tests are used. Enlarged nodes in the vicinity of cancer areas could potentially contain cancer.

Probable patients are observed for few weeks until the cause of lymphadenopathy becomes obvious and they are instructed to return to the doctor if there is increase in node size. Biopsy should be performed in case tests suggest malignancy.

The etiology of the condition is unknown. Possible but unproven infectious causes are "Klebsiella", polyomaviridae, Epstein–Barr virus, parvovirus B19, and human herpesvirus 6. Jilin University researchers suggested in 2017 that monocytes recruited to inflammatory lesions could produce macrophage colony-stimulating factor, which leads to a complex signal transduction, which leads to the histiocytosis characteristic of Rosai–Dorfman disease.

The treatment of a Pancoast lung cancer may differ from that of other types of non-small cell lung cancer. Its position and close proximity to vital structures (such as nerves and spine) may make surgery difficult. As a result, and depending on the stage of the cancer, treatment may involve radiation and chemotherapy given prior to surgery (neoadjuvant treatment).

Surgery may consist of the removal of the upper lobe of a lung together with its associated structures (subclavian artery, vein, branches of the brachial plexus, ribs and vertebral bodies), as well as mediastinal lymphadenectomy. Surgical access may be via thoracotomy from the back or the front of the chest and modifications

In 2016 the Histiocyte Society proposed a classification of histiocytoses into five groups designated by letters: "C," "H," "L," "M," and "R." Group "R" included Rosai–Dorfman disease and "miscellaneous noncutaneous, non-Langerhans cell histiocytoses." Rosai–Dorfman disease itself was classified into "Familial," "Classical (nodal)," "Extranodal," "Neoplasia-associated," and "Immune disease-associated" subtypes.

Inguinal lymphadenopathy causes swollen lymph nodes in the groin area. It can be a symptom of infective or neoplastic processes.

Infective aetiologies include Tuberculosis, HIV, non-specific or reactive lymphadenopathy to recent lower limb infection or groin infections. Another notable infectious cause is Lymphogranuloma venereum, which is a sexually transmitted infection of the lymphatic system. Neoplastic aetiologies include lymphoma, leukaemia and metastatic disease from primary tumours in the lower limb, external genitalia or perianal region and melanoma.

Pneumomediastinum (from Greek "pneuma" – "air", also known as mediastinal emphysema) is (abnormal presence of air or other gas) in the mediastinum. First described in 1819 by René Laennec, the condition can result from physical trauma or other situations that lead to air escaping from the lungs, airways, or bowel into the chest cavity.

Aside from cancer general symptoms such as malaise, fever, weight loss and fatigue, Pancoast tumour can include a complete Horner's syndrome in severe cases: miosis (constriction of the pupils), anhidrosis (lack of sweating), ptosis (drooping of the eyelid) and enophthalmos (sunken eyeball). In progressive cases, the brachial plexus is also affected, causing pain and weakness in the muscles of the arm and hand with a symptomatology typical of thoracic outlet syndrome. The tumour can also compress the recurrent laryngeal nerve and from this a hoarse voice and bovine cough may occur.

In superior vena cava syndrome, obstruction of the superior vena cava by a tumour (mass effect) causes facial swelling cyanosis and dilatation of the veins of the head and neck.

A Pancoast tumor is an apical tumour that is typically found in conjunction with a smoking history. The clinical signs and symptoms can be confused with neurovascular compromise at the level of the superior thoracic aperture. The patient's smoking history, rapid onset of clinical signs and symptoms and pleuritic pain can suggest an apical tumour. A Pancoast tumor can give rise to both Pancoast syndrome and Horner's syndrome. When the brachial plexus roots are involved it will produce Pancoast syndrome; involvement of sympathetic fibres as they exit the cord at T1 and ascend to the superior cervical ganglion will produce Horner's syndrome.

"Lung tumors" are neoplastic tumors of the lung These include:

Primary tumors of the lung/pulmonary system:

- Bronchial leiomyoma, a rare, benign tumor

- Lung cancer, the term commonly used to refer to "carcinoma of the lung"

- Pulmonary carcinoid tumor

- Pleuropulmonary blastoma

- Neuroendocrine tumors of the lung

- Lymphomas of the lung.

- Sarcomas of the lung.

- Some rare vascular tumors of the lung

Non-lung tumors which may grow into the lungs:

- Mediastinal tumors

- Pleural tumors

Metastasis or secondary tumors/neoplasms with other origin:

- Metastasis to the lung