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)

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.

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.

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

Lymphadenopathy can occur in one or more groups of lymph nodes. Among 358 cases of Rosai–Dorfman disease that Rosai collected in a disease registry for which the location of lymphadenopathy was specified, 87.3% had cervical lymphadenopathy. Axillary, inguinal, and mediastinal lymphadenopathy are also found in Rosai–Dorfman disease.

Accumulation of histiocytes may occur outside of lymph nodes. The most common sites of extranodal disease in Rosai's registry were skin, nasal cavity/paranasal sinuses, soft tissue, eyelid/orbit, bone, salivary glands, and central nervous system.

The symptoms of this disease vary with the site of accumulation similar to other regional tumors. For instance, accumulation in closed spaces such as the cranium can lead to poor outcomes compared to growth in the dermis of an extremity where surgical excision is possible.

PTGC is usually characterized by localized lymphadenopathy and is otherwise typically asymptomatic.

Patients with this disease usually present at an advanced stage and show systemic involvement. The clinical findings typically include a pruritic skin rash and possibly edema, ascites, pleural effusions, and arthritis.

Due to the systemic nature of this disease, neoplastic cells can be found in lymph nodes, liver, spleen, skin, and bone marrow.

PTGC is diagnosed by surgical excision of the affected lymph node(s), and examination by a pathologist. The differential diagnosis includes non-neoplastic causes of lymphadenopathy (e.g. cat-scratch fever, Kikuchi disease) and malignancy, i.e. cancer.

Lymph nodes or 'glands' or "nodes" or "lymphoid tissue" are nodular bodies located throughout the body but clustering in certain areas such as the armpit, back of the neck and the groin. They are part of the lymphatic system.

The lymphatic system is part of the body's immune surveillance system. Blood contains fluid and blood cells. The fluid, which may contain suspended foreign material such as bacteria and viruses, seeps through blood vessel walls into the tissues, where it bathes the body cells and exchanges substances with them. Some of this fluid is then taken up by lymphatic vessels and passed back to the heart, where it is again mixed with the blood. On its way the fluid passes through the lymph nodes. If nodes detect something foreign passing through them such as a bacterium or a cancer cell they will swell up. This is called "lymphadenopathy" or "swollen glands". Usually this is localised (for example an infected spot on the scalp will cause lymph nodes in the neck on that same side to swell up), but when it is in two or more regions, it is called "generalized lymphadenopathy".

Usually this is in response to a body-wide infectious disease such as influenza and will go away once the person has recovered, but sometimes it can persist long-term, even when there is no obvious cause of disease. This is then called "persistent generalized lymphadenopathy" (PGL).

Bilateral hilar lymphadenopathy is a bilateral enlargement of the lymph nodes of pulmonary hila. It is a radiographic term that describes the enlargement of mediastinal lymph nodes and is most commonly identified by a chest x-ray.

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.

Axillary lymphadenopathy is lymphadenopathy of the axillary lymph nodes.

Persistent generalized lymphadenopathy (PGL) is enlarged painful lymph nodes occurring in a couple of different areas for more than three to six months for which no other reason can be found. This condition occurs frequently in people in the latency period of HIV/AIDS.

The lymphatic system is part of the immune surveillance system. Blood contains fluid and blood cells. The fluid, which may contain suspended foreign material such as bacteria and viruses, seeps through blood vessel walls into the tissues, where it bathes the body cells and exchanges substances with them. Some of this lymph fluid is then taken up by lymphatic vessels and passed back to the heart, where it is again mixed with the blood. On its way, the fluid passes through the lymph nodes, small nodular organs located throughout the body but concentrated in certain areas such as the armpits or groin. These lymph nodes are also known as "glands" or "lymphoid tissue". If they detect something foreign passing through them, they enlarge. This is called "lymphadenopathy" or "swollen glands". Usually this is localized (for example, an infected spot on the scalp will cause lymph nodes in the neck on that same side to swell). However, when two or more lymph node groups are involved, it is called "generalized lymphadenopathy". Usually this is in response to a significant systemic disease and will subside once the person has recovered. Sometimes it can persist long-term, even when no explanation for the lymphadenopathy can be found.

PGL is often found in cases of autoimmune disease (where the body is attacking itself). These include diseases such as rheumatoid arthritis, lupus and sarcoidosis. Some forms of cancer will also cause PGL. Sometimes, despite exhaustive investigation, no cause for PGL is found. For the patient and the physician, this can continue to be a source of concern, but many adults have had PGL all their lives and suffered no ill effects. In others, the PGL may persist for a decade or more and then mysteriously subside. Children often have generalized lymphadenopathy of the head and neck, or even PGL, without the finding of a sinister cause. At puberty this usually disappears.

The immune system of some people may be sensitized by exposure to a living exogenous irritant such as a bacterial or viral infection, which then results in PGL after the organism has been cleared from the body. In some cases the sensitization is caused by non-living exogenous irritants such as cyclic hydrocarbons (for example, resinous vapours) or pesticides and herbicides.

Follicular hyperplasia (or "reactive follicular hyperplasia" or "lymphoid nodular hyperplasia") is a type of lymphoid hyperplasia. It is caused by a stimulation of the B cell compartment. It is caused by an abnormal proliferation of secondary follicles and occurs principally in the cortex without broaching the lymph node capsule. The follicles are cytologically polymorphous, are often polarized, and vary in size and shape. Follicular hyperplasia is distinguished from follicular lymphoma in its polyclonality and lack of bcl-2 protein expression, whereas follicular lymphoma is monoclonal, and does express bcl-2).

To diagnose this condition, scans or other imaging tests are used. Enlarged nodes in the vicinity of cancer areas could potentially contain cancer.

Probable patients are observed for few weeks until the cause of lymphadenopathy becomes obvious and they are instructed to return to the doctor if there is increase in node size. Biopsy should be performed in case tests suggest malignancy.

Mediastinal lymphadenopathy or mediastinal adenopathy is an enlargement of the Mediastinal lymph nodes

Atypical infections are the key clinical manifestation of SGD. Within the first few years of life, patients will experience repeated pyogenic infections by species such as "Staphylococcus aureus", "Pseudomonas aeruginosa" or other Enterobacteriaceae, and "Candida albicans". Cutaneous ulcers or abscesses and pneumonia and chronic lung disease are common. Patients may also develop sepsis, mastoiditis, otitis media, and lymphadenopathy. Infants may present with vomiting, diarrhea, and failure to thrive.

Diagnosis can be made based upon CEBPE gene mutation or a pathognomonic finding of a blood smear showing lack of specific granules. Neutrophils and eosinophils will contain hyposegmented nuclei (a pseudo-Pelger–Huet anomaly).

The Xanthogranulomatous Process (XP), also known as Xanthogranulomatous Inflammation is a form of acute and chronic inflammation characterized by an exuberant clustering of foamy macrophages among other inflammatory cells. Localization in the kidney and renal pelvis has been the most frequent and better known occurrence followed by that in the gallbladder but many others have been subsequently recorded. The pathological findings of the process and etiopathogenetic and clinical observations have been reviewed by Cozzutto and Carbone.

.Letterer-Siwe is characterized by skin lesions, ear drainage, lymphadenopathy, osteolytic lesions, and hepatosplenomegaly. The skin lesions are scaly and may involve the scalp, ear canals, and abdomen.

Some specific reactive lymphadenopathies with a predominantly follicular pattern:

- Rheumatoid arthritis

- Sjogren syndrome

- IgG4-related disease (IgG4-related lymphadenopathy)

- Kimura disease

- Toxoplasmosis

- Syphilis

- Castleman disease

- HIV-associated lymphadenopathy

- Progressive transformation of germinal centers (PTGC)

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.

IPMs present as painless lymphadenopathy. They usually are found in the inguinal region and grow slowly.

The signs and symptoms are non-specific, i.e. it is not possible to diagnose an IPM from the symptoms and manner in which they present.

The main (clinical) differential diagnosis of IPM is metastatic cancer, e.g. squamous cell carcinoma, malignant melanoma, adenocarcinoma.

Sézary syndrome and mycosis fungoides are T-cell lymphomas whose primary manifestation is in the skin. The disease's origin is a peripheral CD4+ T-lymphocyte, although rarer CD8+/CD4- cases have been observed. Epidermotropism by neoplastic CD4+ lymphocytes with the formation of Pautrier's microabscesses is the hallmark sign of the disease. The dominant symptoms of the disease are:

1. Generalized erythroderma

2. Lymphadenopathy

3. Atypical T-cells ("Sézary cells") in the peripheral blood

4. Hepatosplenomegaly

5. Palmoplantar keratoderma