Lymphadenopathy or adenopathy is disease of the lymph nodes, in which they are abnormal in size, number, or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In clinical practice, the distinction between lymphadenopathy and lymphadenitis is rarely made and the words are usually treated as synonymous. Inflammation of the lymphatic vessels is known as lymphangitis. Infectious lymphadenitides affecting lymph nodes in the neck are often called scrofula.
The term comes from the word lymph and a combination of the Greek words αδένας, adenas ("gland") and παθεία, patheia ("act of suffering" or "disease").
Lymphadenopathy is a common and nonspecific sign. Common causes include infections (from minor ones such as the common cold to dangerous ones such as HIV/AIDS), autoimmune diseases, and cancers. Lymphadenopathy is also frequently idiopathic and self-limiting.
By size, lymphadenopathy in adults is present when the short axis of one or more lymph nodes is greater than 10mm. However, inguinal lymph nodes may normally be up to 2 cm.In children, a short axis of 8 mm can be used. However, inguinal lymph nodes of up to 1.5 and
cervical lymph nodes of up to 2 cm are generally normal in children up to age 8-12.
By extent: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 upGeneralized lymphadenopathy: due to a systemic infection of the body e.g., influenza or secondary syphilisPersistent generalized lymphadenopathy (PGL): persisting for a long time, possibly without an apparent causeBy malignancy: Benign lymphadenopathy is distinguished from malignant causes which mainly refer to lymphomas or lymph node metastasisBy localization, including hilar lymphadenopathy.Dermatopathic lymphadenopathy: lymphadenopathy associated with skin 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 trypanosomiasisToxoplasmosis, a parasitic disease, gives a generalized lymphadenopathy (Piringer-Kuchinka lymphadenopathy).Plasma cell variant of Castleman's disease - associated with HHV-8 infection and HIV infectionMesenteric 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 etiology: systemic lupus erythematosus and rheumatoid arthritis may have 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 such as the pit viperUnknown etiology: Kikuchi disease, progressive transformation of germinal centers, sarcoidosis, hyaline-vascular variant of Castleman's disease, Rosai-Dorfman disease, Kawasaki disease, Kimura diseaseBenign lymphadenopathy is a common biopsy finding, and may often be confused with malignant lymphoma. It may be separated into major morphologic patterns, each with its own differential diagnosis with certain types of lymphoma. Most cases of reactive follicular hyperplasia are easy to diagnose, but some cases may be confused with follicular lymphoma. There are seven distinct patterns of benign lymphadenopathy:
Follicular hyperplasia: This is the most common type of reactive lymphadenopathy.Paracortical hyperplasia/Interfollicular hyperplasia: It is seen in viral infections, skin diseases, and nonspecific reactions.Sinus histiocytosis: It is seen in lymph nodes draining limbs, inflammatory lesions, and malignancies.Nodal extensive necrosisNodal granulomatous inflammationNodal extensive fibrosis (Connective tissue framework)Nodal deposition of interstitial substanceThese morphological patterns are never pure. Thus, reactive follicular hyperplasia can have a component of paracortical hyperplasia. However, this distinction is important for the differential diagnosis of the cause.
Mediastinal lymphadenopathyBilateral hilar lymphadenopathy 
