Adenitis is inflammation of a gland or lymph node, most often caused by an infection. The term covers several specific conditions depending on which glands or nodes are affected. The most common forms involve lymph nodes in the neck (cervical adenitis) or the abdomen (mesenteric adenitis), and they range from mild, self-resolving episodes to infections that need treatment.
How Adenitis Differs From Lymphadenopathy
You’ll sometimes see “adenitis,” “lymphadenitis,” and “lymphadenopathy” used loosely as though they mean the same thing. They don’t. Lymphadenopathy is the broader term: it refers to any lymph node that’s abnormal in size or consistency, whether from infection, autoimmune disease, or cancer. Lymphadenitis is more specific. It describes lymph nodes that are inflamed, meaning there’s not just swelling but also pain, skin changes, fever, or pus formation. Adenitis can apply to lymph nodes or to other types of glands, like the sebaceous (oil-producing) glands in the skin.
Common Types of Adenitis
Cervical Adenitis
This is inflammation of the lymph nodes in the neck, and it’s the form most people encounter. When both sides of the neck are swollen, the cause is usually a viral upper respiratory infection or strep throat. When only one side is affected, a bacterial infection is responsible in 40% to 80% of cases, typically staph or strep bacteria. You’ll notice tender, swollen lumps along the jaw or sides of the neck, often with fever and sore throat.
Mesenteric Adenitis
Mesenteric adenitis involves the lymph nodes inside the abdomen, specifically in the tissue (mesentery) that anchors the intestines. It causes sudden pain in the lower right side of the belly, fever, vomiting, and changes in bowel habits. Because the pain sits in the same spot, it’s frequently mistaken for appendicitis. In children under ten, lower right abdominal pain is actually more likely to be mesenteric adenitis than appendicitis.
One practical distinction: the tenderness during a physical exam tends to be milder with mesenteric adenitis than with true appendicitis. An ultrasound can usually tell the two apart by showing enlarged lymph nodes without the telltale swollen appendix.
Sebaceous Adenitis
This rarer form involves inflammation of the oil-producing glands in the skin. It’s far more common in animals than humans. When it does appear in people, it typically shows up as tender nodules on the face, chest, or vulvar area. The nodules can discharge pus, but cultures usually come back negative for bacteria, suggesting the inflammation is driven by the immune system rather than infection.
What Causes It
Infections are the leading trigger. Viral illnesses, especially common colds and upper respiratory infections, account for the majority of cases. Bacterial causes include strep and staph infections, tuberculosis, and cat scratch disease (caused by the bacterium Bartonella). Other infectious agents linked to adenitis include Epstein-Barr virus (which causes mono), cytomegalovirus, HIV, syphilis, and certain fungal organisms like histoplasmosis and cryptococcosis.
Non-infectious causes also exist. Autoimmune conditions like lupus and sarcoidosis can produce chronic lymph node inflammation. Inflammatory bowel disease, hyperthyroidism, and certain metabolic storage diseases are additional possibilities. Lymphoma and other cancers can cause persistent lymph node enlargement too, which is why nodes that stay swollen for weeks without a clear infection deserve medical evaluation.
How Adenitis Is Classified by Duration
Doctors categorize lymph node inflammation by how long it lasts. Acute adenitis resolves within two weeks and is usually viral. Subacute adenitis lasts two to six weeks. Chronic adenitis persists beyond six weeks, and at that point the list of possible causes shifts toward tuberculosis, autoimmune disease, cat scratch disease, sarcoidosis, and cancer.
How It’s Diagnosed
For cervical adenitis, diagnosis often starts with a physical exam and basic blood work to check for signs of infection. If bacterial infection is suspected, a throat swab or needle sample from the node can identify the specific organism.
For mesenteric adenitis, ultrasound is the primary tool. It reveals clusters of enlarged lymph nodes in the abdomen while also confirming the appendix looks normal. This distinction matters because enlarged lymph nodes can appear alongside appendicitis too, though the nodes tend to be smaller and fewer in number when the appendix is the real problem.
Treatment and Recovery
Most adenitis caused by viruses doesn’t need specific treatment. It resolves on its own with rest, fluids, and over-the-counter pain relief. Viral cervical adenitis typically clears within 7 to 10 days, and the nodes rarely develop abscesses.
Bacterial adenitis usually requires antibiotics targeted at the likely bacteria. For neck infections without a clear source, treatment needs to cover both staph and strep. If an abscess forms, drainage may be necessary.
Mesenteric adenitis is considered self-limiting, meaning it resolves without specific treatment in most cases. Recovery is commonly assumed to take about four weeks, but a study tracking outcomes found a bimodal pattern: roughly half of children recovered within two weeks, while the other half had symptoms lasting three to ten weeks. There were no reliable clinical differences between the quick and slow recoverers, so a longer course doesn’t necessarily signal something more serious.
Potential Complications
Most cases of adenitis, particularly viral ones, resolve without complications. Bacterial adenitis carries more risk if left untreated. Staph and strep infections can progress to abscess formation, where pus collects inside or around the lymph node. Cat scratch disease develops into a suppurative (pus-forming) phase in about 10% to 15% of cases, sometimes lasting months with abscess and fistula formation.
Infections caused by certain slow-growing bacteria, particularly nontuberculous mycobacteria, can eventually rupture through the skin and create draining tracts that discharge pus over a prolonged period. This complication is uncommon but reinforces why persistent, worsening lymph node swelling warrants follow-up rather than a wait-and-see approach.