Lymphadenopathy, or enlarged lymph nodes, may be the result of acute inflammation, chronic inflammation, or infiltration via malignant cells. Lymphadenitis is the term used to describe inflammation of lymph nodes.
Most cases of acute cervical lymphadenitis are caused by either staphylococcal or streptococcal infections, and the changing epidemiology of acute unilateral cervical adenitis has been well documented in the literature. In 1944, Powers and Boisvert reported that 79% of cervical abscesses were caused by group A beta-hemolytic Streptococcus (GABHS; Streptococcus pyogenes) and only 17% were caused by Staphylococcus aureus (formerly S. pyogenes). In 1969, Scobie reported that Staphylococcus species caused most (67%) cases of cervical adenitis, and only 7% were caused by streptococci.1
Nontuberculosis mycobacterium (NTM) infections in the head and neck are common among children.2 NTM includes mycobacterial species Mycobacterium avium-intracellulare complex, Mycobacterium scrofulaceum, Mycobacterium fortuitum, and Mycobacterium chelonei. NTM are ubiquitous in the environment and can be found in soil, contaminated water, dairy products, eggs, and dust. NTM are endemic in certain regions of the United States such as the mid-west and southwest. Ingestion of contaminated materials is likely to be the main route for introduction of NTM. This explains why cervicofacial lymph nodes are the sites primarily affected by NTM infections.2 Until approximately 50 years ago, adenitis caused by Mycobacterium tuberculosis (TB) and Mycobacterium bovis were more common than NTM adenitis. However, as TB and M. bovis disease decreased in the United States and other developed countries, NTM became a major cause of chronic lymphadenitis in children. Cessation of Bacille Calmette–Guerin vaccination in the United States has decreased collateral immunity against NTM. Chlorination of water has also been attributed to decrease in number of infections caused by M. scrofulaceum.3
Peripheral tuberculous lymphadenitis involves mainly the cervical lymph nodes. It is the most common form of extrapulmonary tuberculosis in children from tuberculosis-endemic areas. Lymphadenitis is thought to occur secondary to a lymphatic spread of organisms from a primary pulmonary focus. However, it can occasionally occur from primary focus in the mouth, tonsils, oropharynx, or tissues of the head and neck.4
Cat-scratch disease (CSD) was first reported by Debre in 1950 as a syndrome of regional lymphadenopathy after a cat scratch. CSD is caused by infection with Bartonella henselae, a zoonotic disease.5,6 Cat fleas Ctenocephalides felis transmit B. henselae between cats who remain asymptomatic. Humans become infected after exposure to infected cats, usually after scratches or bites from kittens. Dogs have also been known to be the vector for transmitting the disease. The true incidence of CSD is unknown. Most cases occur in people younger than 20 years. More than 90% of patients with CSD have a history of recent contact with cats, often kittens.7 Infection is reported to occur more often during the autumn and winter. The incubation period from the time of the scratch to appearance ...