Lymphadenopathy

Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy.

Inflammation of a lymph node is called lymphadenitis. In practice, the distinction between lymphadenopathy and lymphadenitis is rarely made. (Inflammation of lymph channels is called lymphangitis. )

Types
Tangier disease (ABCA1 deficiency) may also cause this
 * Localized lymphadenopathy : due to localized spot of infection e.g. an infected spot on the scalp will cause lymph nodes in the neck on that same side to swell up
 * Generalized lymphadenopathy : due to generalized infection all over the body e.g. influenza
 * persistent generalized lymphadenopathy (PGL) : persisting for a long time, possibly without an apparent cause
 * Dermatopathic lymphadenopathy : lymphadenopathy associated with skin disease.

Cause
Enlarged lymph nodes are a common symptom in a number of infectious and malignant diseases. It is a recognized symptom of very many diseases, of which some are as follows:
 * Reactive: acute infection (e.g. bacterial, or viral), or chronic infections (tuberculous lymphadenitis, cat-scratch disease).
 * The most distinctive symptom 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, the hallmark of which is marked enlargement of the cervical lymph nodes.
 * It is also a symptom of cutaneous anthrax, measles and Human African trypanosomiasis, the latter two giving lymphadenopathy in lymph nodes in the neck.
 * 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.


 * Tumoral:
 * Primary: Hodgkin lymphoma and non-Hodgkin lymphoma give lymphadenopathy in all or a few lymph nodes.
 * Secondary: metastasis, Virchow's Node, Neuroblastoma.


 * Autoimmune etiology: systemic lupus erythematosus, rheumatoid arthritis all giving a generalized lymphadenopathy.


 * Immunocompromised etiology: 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, most notably the black mamba, kraits, Australian brown snakes, coral snakes, tiger snakes, taipans, death adders, and some of the more toxic species of cobra.


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

Benign (reactive) lymphadenopathy
There are three distinct patterns of benign lymphadenopathy:
 * Follicular hyperplasia - Seen in infections, autoimmune disorders, and nonspecific reactions.
 * Paracortical hyperplasia - Seen in viral infections, skin diseases, and nonspecific reactions.
 * Sinus histiocytosis - Seen in lymph nodes draining limbs, inflammatory lesions, and malignancies.

Bilateral hilar lymphadenopathy
Bilateral hilar lymphadenopathy (BHL) is a radiographic term that describes the enlargement of mediastinal lymph nodes. It is easily and most commonly identified by a chest x-ray.

Causes of BHL
The following are causes of BHL:
 * Sarcoidosis
 * Infection
 * Tuberculosis
 * Mycoplasma
 * Intestinal Lipodystrophy (Whipple's Disease)
 * Malignancy
 * Lymphoma
 * Carcinoma
 * Mediastinal tumors
 * Organic dust disease
 * Silicosis
 * Berylliosis
 * Extrinsic allergic alveolitis
 * Such as bird fancier's lung
 * Less common causes also exist:
 * Churg-Strauss syndrome
 * Human immunodeficiency virus
 * Extrinsic allergic alveolitis
 * Pneumoconiosis
 * Adult-onset Still's disease