Adenitis is a general term for an inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 of a gland

Gland

A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...

 or lymph node

Lymph node

A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

.

Lymph node adenitis

"Lymph adenitis" or "lymph node adenitis" is caused by bacterial infection in lymph nodes. The infected lymph nodes typically become enlarged, warm and tender. A swelling of lymph nodes due to growth of lymph cells is called lymphadenopathy

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....

. Types include:

• Neck
  • Cervical adenitis is an inflammation of a lymph node in the neck
    Neck
    The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...
    
    .
  • Tuberculous adenitis (scrofula
    Scrofula
    Tuberculous cervical lymphadenitis refers to a lymphadenitis of the cervical lymph nodes associated with tuberculosis. It was previously known as "scrofula".-The disease:...
    
    ) is a tuberculous infection of the skin of the neck caused by Mycobacterium tuberculosis
    Mycobacterium tuberculosis
    Mycobacterium tuberculosis is a pathogenic bacterial species in the genus Mycobacterium and the causative agent of most cases of tuberculosis . First discovered in 1882 by Robert Koch, M...
    
    . Non-tuberculous adenitis can also be caused by Mycobacterium scrofulaceum
    Mycobacterium scrofulaceum
    Mycobacterium scrofulaceum is a species of Mycobacterium.It is the most common cause of cervical lymphadenitis in children.It is sometimes included in the "MAIS group" with Mycobacterium avium and Mycobacterium intracellulare....
    
    or Mycobacterium avium.

• Abdomen
  • Mesenteric adenitis is an inflammation of the mesenteric
    Mesentery
    In anatomy, the mesentery is the double layer of peritoneum that suspends the jejunum and ileum from the posterior wall of the abdomen. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.-Mesentery :The...
    
     lymph nodes in the abdomen. If it occurs in the right lower quadrant, it can be mistaken for acute appendicitis
    Appendicitis
    Appendicitis is a condition characterized by inflammation of the appendix. It is classified as a medical emergency and many cases require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly because of the risk of rupture leading to...
    
    , often preceded by a sore throat.

Other

Sebaceous adenitis is an inflammation of the sebaceous gland

Sebaceous gland

The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...

s
in the skin. These glands normally produce sebum (skin oil, a lipid-rich secretion) which prevents drying o f the skin.