Lymphadenopathy of the axillary lymph nodes can be defined as solid nodes measuring more than 15 mm without fatty hilum. Axillary lymph nodes may be normal up to 30 mm if consisting largely of fat.

"Lymph adenitis" or "lymph node adenitis" is caused by 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. Types include:

- Neck

- Cervical adenitis is an inflammation of a lymph node in the neck.

- Tuberculous adenitis (scrofula) is a tuberculous infection of the skin of the neck caused by "Mycobacterium tuberculosis". Non-tuberculous adenitis can also be caused by "Mycobacterium scrofulaceum" or "Mycobacterium avium".

- Abdomen

- Mesenteric adenitis is an inflammation of the mesenteric lymph nodes in the abdomen. It can be caused by the bacterium "Yersinia enterocolitica". If it occurs in the right lower quadrant, it can be mistaken for acute appendicitis, often preceded by a sore throat.

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 , "adenas" ("gland") and , "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.

Rhinoscleroma has been divided into 3 stages: catarrhal/atrophic, granulomatous, and sclerotic stages. The catarrhal stage begins with a nonspecific rhinitis, which progresses into purulent, fetid rhinorrhea, and crusting, which can last for weeks or even months. The granulomatous stage results in the development of a bluish red nasal mucosa and the development of intranasal rubbery nodules or polyps. Nose bleeds, nasal deformity, and destruction of the nasal cartilage are also noted (Hebra nose). The damage may result in anesthesia of the soft palate, enlargement of the uvula, dysphonia, and various degrees of airway obstruction. The fibrotic stage is characterized by sclerosis and fibrosis. Lymphadenitis is absent.

The first symptom is a sudden onset of swelling of the face, which develops within two days into papules and pustues on the lips, nose, and around the eyes. These pustules release a purulent discharge, causing a crust to form on the skin. There is also lymphadenopathy (swelling of lymph nodes) in the main lymph nodes of the head. The feet, body, prepuce or perianal area may be affected. Pustular otitis externa can occur, with the pinnae (ear flaps) becoming thickened by edema. Affected areas are painful but not itchy. Approximately half of affected puppies have lethargy and depression. Less common symptoms include pyrexia, anorexia, and joint pain, caused by sterile suppurative arthritis.

Sebaceous adenitis is an inflammation of the sebaceous glands

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

Tuberculous lymphadenitis (or tuberculous adenitis) is a chronic specific granulomatous inflammation of the lymph node with caseation necrosis, caused by infection with "Mycobacterium tuberculosis" or "Mycobacterium bovis".

The characteristic morphological element is the tuberculous granuloma (caseating tubercule). This consists of giant multinucleated cells and (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and fibroblasts. Granulomatous tubercules eventually develop central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.

Stages of tubercular lymphadenitis:

1. Lymphadenitis

2. Periadenitis

3. Cold abscess

4. 'Collar stud' abscess

5. Sinus

Tuberculous lymphadenitis is popularly known as collar stud abscess, due to its proximity to the collar bone and superficial resemblance to a collar stud, although this is just one of the five stages of the disease. The characteristic morphological element is the tuberculous granuloma (caseating tubercule): giant multinucleated cells (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and few fibroblasts. Granulomatous tubercules evolve to central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.

Lymphangitis is an inflammation or an infection of the lymphatic channels that occurs as a result of infection at a site distal to the channel. The most common cause of lymphangitis in humans is "Streptococcus pyogenes" (Group A strep), although it can also be caused by the fungus "Sporothrix schenckii". Lymphangitis is sometimes mistakenly called "blood poisoning". In reality, "blood poisoning" is synonymous with "sepsis".

Signs and symptoms include a deep reddening of the skin, warmth, lymphadenitis (inflammation of a lymphatic gland), and a raised border around the affected area. The person may also have chills and a high fever along with moderate pain and swelling. A person with lymphangitis should be hospitalized and closely monitored by medical professionals.

Lymphangitis is the inflammation of the lymphatic vessels and channels. This is characterized by certain inflammatory conditions of the skin caused by bacterial infections. Thin red lines may be observed running along the course of the lymphatic vessels in the affected area, accompanied by painful enlargement of the nearby lymph nodes.

When the inferior limbs are affected, the redness of the skin runs over the great saphenous vein location and confusion can be made with a thrombophlebitis.

Chronic lymphangitis is a cutaneous condition that is the result of recurrent bouts of acute bacterial lymphangitis.

Rhinoscleroma, or simply scleroma, is a chronic granulomatous bacterial disease of the nose that can sometimes infect the upper respiratory tract. It most commonly affects the nasal cavity—the nose is involved in 95–100 per cent of cases—however, it can also affect the nasopharynx, larynx, trachea, and bronchi. Slightly more females than males are affected and patients are usually 10 to 30 years of age. Rhinoscleroma is considered a tropical disease and is mostly endemic to Africa and Central America, less common in the United States.

The secondary stage most often occurs 10–30 days later, but can present up to six months later. The infection spreads to the lymph nodes through lymphatic drainage pathways. The most frequent presenting clinical manifestation of LGV among males whose primary exposure was genital is unilateral (in 2/3 of cases) lymphadenitis and lymphangitis, often with tender inguinal and/or femoral lymphadenopathy because of the drainage pathway for their likely infected areas. Lymphangitis of the dorsal penis may also occur and resembles a string or cord. If the route was anal sex the infected person may experience lymphadenitis and lymphangitis noted above. They may instead develop proctitis, inflammation limited to the rectum (the distal 10–12 cm) that may be associated with anorectal pain, tenesmus, and rectal discharge, or proctocolitis, inflammation of the colonic mucosa extending to 12 cm above the anus and associated with symptoms of proctitis plus diarrhea or abdominal cramps.

In addition, symptoms may include inflammatory involvement of the perirectal or perianal lymphatic tissues. In females, cervicitis, perimetritis, or salpingitis may occur as well as lymphangitis and lymphadenitis in deeper nodes. Because of lymphatic drainage pathways, some patients develop an abdominal mass which seldom suppurates, and 20–30% develop inguinal lymphadenopathy. Systemic signs which can appear include fever, decreased appetite, and malaise. Diagnosis is more difficult in women and men who have sex with men (MSM) who may not have the inguinal symptoms.

Over the course of the disease, lymph nodes enlarge, as may occur in any infection of the same areas as well. Enlarged nodes are called buboes. Buboes are commonly painful. Nodes commonly become inflamed, thinning and fixation of the overlying skin. These changes may progress to necrosis, fluctuant and suppurative lymph nodes, abscesses, fistulas, strictures, and sinus tracts. During the infection and when it subsides and healing takes place, fibrosis may occur. This can result in varying degrees of lymphatic obstruction, chronic edema, and strictures. These late stages characterised by fibrosis and edema are also known as the third stage of LGV and are mainly permanent.

LGV may begin as a self-limited painless genital ulcer that occurs at the contact site 3–12 days after infection. Women rarely notice a primary infection because the initial ulceration where the organism penetrates the mucosal layer is often located out of sight, in the vaginal wall. In men fewer than 1/3 of those infected notice the first signs of LGV. This primary stage heals in a few days. Erythema nodosum occurs in 10% of cases.

Juvenile cellulitis, also known as puppy strangles or juvenile pyoderma, is an uncommon disease of dogs. Symptoms include dermatitis, lethargy, depression and lameness. When puppies are first presented with what appears to be staphylococcal pyoderma, juvenile cellulitis, a relatively rare condition, may not be considered.

Paraproctitis is a purulent inflammation of the cellular tissues surrounding the rectum. The most frequent cause is penetration of bacterial flora from the rectum into the surrounding cellular tissues, which may occur through an anal fissure. The inflammation is sometimes limited to the formation of an abscess, and in some cases it spreads for a considerable distance and may be complicated by sepsis.

The symptoms are acute pain in the rectal region, tenderness during defecation, elevated body temperature, and the appearance of an infiltrate in the anal region or on the buttocks. An unlanced abscess may burst and a fistula form. The disease becomes chronic after recurrences. Treatment includes administration of antibiotics and anti-inflammatory agents and, in the suppurative stage, surgical lancing of the abscess.

In most cases AIT is characterized by onset of pain, firmness, tenderness, redness or swelling in the anterior aspect of the neck. Patients will also present with a sudden fever, dysphagia and dysphonia. Symptoms may be present from 1 to 180 days, with most symptoms lasting an average of about 18 days. The main issue associated with the diagnosis of AIT is differentiating it from other more commonly seen forms of thyroid conditions. Pain, fever and swelling are often much more severe and continue to get worse in patients who have AIT compared to those with other thyroid conditions. Patients who are suspected of having AIT often undergo tests to detect for elevated levels of white blood cells as well as an ultrasound to reveal unilobular swelling. Depending on the age and immune status of the patient more invasive procedures may be performed such as fine needle aspiration of the neck mass to facilitate a diagnosis.

In cases where the infection is thought to be associated with a sinus fistula it is often necessary to confirm the presence of the fistula through surgery or laryngoscopic examination. While invasive procedures can often tell definitively whether or not a fistula is present, new studies are working on the use of computed tomography as a useful method to visualize and detect the presence of a sinus fistula.

Necrotizing granulomas can develop in patients with rheumatoid arthritis, typically manifesting as bumps in the soft tissues around the joints (so-called rheumatoid nodules) or in the lungs.

Acute infectious thyroiditis (AIT) also known as suppurative thyroiditis, microbial inflammatory thyroiditis, pyrogenic thyroiditis and bacterial thyroiditis.

The thyroid is normally very resistant to infection. Due to a relatively high amount of iodine in the tissue, as well as high vascularity and lymphatic drainage to the region, it is difficult for pathogens to infect the thyroid tissue. Despite all this, a persistent fistula from the piriform sinus may make the left lobe of the thyroid susceptible to infection and abscess formation. AIT is most often caused by a bacterial infection but can also be caused by a fungal or parasitic infection, most commonly in an immunocompromised host.

A foreign-body granuloma occurs when a foreign body (such as a wood splinter, piece of metal, glass etc.) penetrates the body's soft tissue followed by acute inflammation and formation of a granuloma. In some cases the foreign body can be found and removed even years after the precipitating event.

Cervical lymphadenopathy can be thought of as "local" where only the cervical lymph nodes are affected, or "general" where all the lymph nodes of the body are affected.

Dermatopathic lymphadenopathy is diagnosed by a lymph node biopsy. It has a characteristic pattern of histomorphology and immunohistochemical staining:

- Paracortical histiocytosis

- Melanin-laden macrophages

- Eosinophils

- Plasma cells (medulla of lymph node)

Scrofuloderma (also known as "Tuberculosis cutis colliquativa") is a skin condition caused by tuberculous involvement of the skin by direct extension, usually from underlying tuberculous lymphadenitis.

Cervical lymphadenopathy refers to lymphadenopathy of the cervical lymph nodes (the glands in the neck). The term "lymphadenopathy" strictly speaking refers to disease of the lymph nodes, though it is often used to describe the enlargement of the lymph nodes. Similarly, the term "lymphadenitis" refers to inflammation of a lymph node, but often it is used as a synonym of lymphadenopathy.

Cervical lymphadenopathy is a sign or a symptom, not a diagnosis. The causes are varied, and may be inflammatory, degenerative, or neoplastic. In adults, healthy lymph nodes can be palpable (able to be felt), in the axilla, neck and groin. In children up to the age of 12 cervical nodes up to 1 cm in size may be palpable and this may not signify any disease. If nodes heal by resolution or scarring after being inflamed, they may remain palpable thereafter. In children, most palpable cervical lymphadenopathy is reactive or infective. In individuals over the age of 50, metastatic enlargement from cancers (most commonly squamous cell carcinomas) of the aerodigestive tract should be considered.

Hidradenitis is any disease in which the histologic abnormality is primarily an inflammatory infiltrate around the eccrine glands. This group includes neutrophilic eccrine hidradenitis and recurrent palmoplantar hidradenitis.

It can also be defined more generally as an inflammation of sweat glands.

Hidradenitis suppurativa is a chronic cutaneous condition originally thought to be primarily characterized by suppurative inflammation of the apocrine sweat glands. However, recent evidence supports that the primary event is follicular hyperkeratosis and obstruction.

In pathology, dermatopathic lymphadenopathy, also dermatopathic lymphadenitis, is lymph node pathology due to skin disease.

The signs and symptoms of Kikuchi disease are fever, enlargement of the lymph nodes (lymphadenopathy), skin rashes, and headache. Rarely, enlargement of the liver and spleen and nervous system involvement resembling meningitis are seen. Often a bout of extreme fatigue can occur - often taking hold during latter parts of the day and the affected person can be more prone to fatigue from exercise.