Excellent for single-focus disease. With multi-focal disease 60% have a chronic course, 30% achieve remission and mortality is up to 10%.

A similar disease is diffuse histiocytic sarcoma, a term used to designate a localized histiocytic sarcoma that has spread throughout the body.

Another disease of histiocytic origin that affects Bernese Mountain Dogs is systemic histiocytosis. This condition generally begins as lesions on the eyelids, nasal mucosa, and skin, especially the scrotum. It progresses to a more generalized disease affecting the lymph nodes, bone marrow and spleen. Other signs and symptoms include weight loss and loss of appetite. It also has a very poor prognosis.

LCH usually affects children between 1 and 15 years old, with a peak incidence between 5 and 10 years of age. Among children under the age of 10, yearly incidence is thought to be 1 in 200,000; and in adults even rarer, in about 1 in 560,000. It has been reported in elderly but is vanishingly rare. It is most prevalent in Caucasians, and affects males twice as often as females. In other populations too the prevalence in males is slightly more than in females.

LCH is usually a sporadic and non-hereditary condition but familial clustering has been noted in limited number of cases. Hashimoto-Pritzker disease is a congenital self-healing variant of Hand-Schüller-Christian disease.

Malignant histiocytosis (also known as "Histiocytic medullary reticulosis") is a rare hereditary disease found in the Bernese Mountain Dog and humans, characterized by histiocytic infiltration of the lungs and lymph nodes. The liver, spleen, and central nervous system can also be affected. Histiocytes are a component of the immune system that proliferate abnormally in this disease. In addition to its importance in veterinary medicine, the condition is also important in human pathology.

Lymph node abnormalities and organ dysfunction in Castleman disease are caused by excessive secretion of cytokines. IL-6 is the most commonly elevated cytokine, but some affected people may have normal IL-6 levels and present with non-iron-deficient microcytic anemia.

The release of these cytokines is caused by infection with Human herpesvirus 8 in HHV-8-associated MCD. The cause of the release of cytokines in idiopathic MCD has been hypothesized to be caused by either a somatic mutation, a germline genetic mutation, or a non-HHV-8-virus.

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

The etiology of the condition is unknown. Possible but unproven infectious causes are "Klebsiella", polyomaviridae, Epstein–Barr virus, parvovirus B19, and human herpesvirus 6. Jilin University researchers suggested in 2017 that monocytes recruited to inflammatory lesions could produce macrophage colony-stimulating factor, which leads to a complex signal transduction, which leads to the histiocytosis characteristic of Rosai–Dorfman disease.

MCD clinical features range from waxing and waning mild enlargement of the lymph nodes with B symptoms to more severe cases involving intense inflammation, widespread enlargement of lymph nodes enlargement of the liver and spleen, vascular leak syndrome with anasarca, fluid collections in the space around the lungs, and fluid collection in the abdomen's peritoneal space, organ failure, and even death. The most common 'B Symptoms' of MCD are high fevers, night sweats, weight loss, and loss of appetite. Acute episodes can display significant clinical overlap with acute viral illnesses, autoimmune diseases, hematologic malignancies, and even sepsis. Laboratory findings commonly include low red blood cell count, low or high platelet counts, low albumin, high gamma globulin levels, elevated C-reactive protein levels, elevated erythrocyte sedimentation rate, IL-6, vascular endothelial growth factor (VEGF), and fibrinogen; positive anti-nuclear antibody, anti-erythrocyte autoantibodies, and anti-platelet antibodies; and protein spilling into the urine, and polyclonal marrow plasmacytosis. Castleman disease is seen in POEMS syndrome and is implicated in 10% of cases of paraneoplastic pemphigus.

Lymph node enlargement is recognized as a common sign of infectious, autoimmune, or malignant disease. Examples may include:

- Reactive: acute infection ("e.g.," bacterial, or viral), or chronic infections (tuberculous lymphadenitis, cat-scratch disease).

- The most distinctive sign of bubonic plague is extreme swelling of one or more lymph nodes that bulge out of the skin as "buboes." The buboes often become necrotic and may even rupture.

- Infectious mononucleosis is an acute viral infection caused by Epstein-Barr virus and may be characterized by a marked enlargement of the cervical lymph nodes.

- It is also a sign of cutaneous anthrax and Human African trypanosomiasis

- Toxoplasmosis, a parasitic disease, gives a generalized lymphadenopathy ("Piringer-Kuchinka lymphadenopathy").

- Plasma cell variant of Castleman's disease - associated with HHV-8 infection and HIV infection

- Mesenteric lymphadenitis after viral systemic infection (particularly in the GALT in the appendix) can commonly present like appendicitis.

Less common infectious causes of lymphadenopathy may include bacterial infections such as cat scratch disease, tularemia, brucellosis, or prevotella.

- Tumoral:

- Primary: Hodgkin lymphoma and non-Hodgkin lymphoma give lymphadenopathy in all or a few lymph nodes.

- Secondary: metastasis, Virchow's Node, neuroblastoma, and chronic lymphocytic leukemia.

- Autoimmune: systemic lupus erythematosus and rheumatoid arthritis may have a generalized lymphadenopathy.

- Immunocompromised: AIDS. Generalized lymphadenopathy is an early sign of infection with human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). "Lymphadenopathy syndrome" has been used to describe the first symptomatic stage of HIV progression, preceding a diagnosis of AIDS.

- Bites from certain venomous snakes such as the pit viper

- Unknown: Kikuchi disease, progressive transformation of germinal centers, sarcoidosis, hyaline-vascular variant of Castleman's disease, Rosai-Dorfman disease, Kawasaki disease, Kimura disease

In 2016 the Histiocyte Society proposed a classification of histiocytoses into five groups designated by letters: "C," "H," "L," "M," and "R." Group "R" included Rosai–Dorfman disease and "miscellaneous noncutaneous, non-Langerhans cell histiocytoses." Rosai–Dorfman disease itself was classified into "Familial," "Classical (nodal)," "Extranodal," "Neoplasia-associated," and "Immune disease-associated" subtypes.

Histologic transformation to diffuse large B-cell lymphoma (DLBCL) can occur in up to 12% of cases. After transformation, neoplastic cells carry monoclonal immunoglobulin gene rearrangements. Histological transformation may lead to poor prognosis and therefore repeat biopsy is required at relapse.

One study found a transformation rate of 7.6%, and suggested that prior exposure to chemotherapy and a presentation with splenic involvement were associated with increased risks of transformation.

Lymphoid hyperplasia is the rapid growth proliferation of normal cells that resemble lymph tissue.

One study has suggested improved overall survival in response to chemotherapy for African Americans.

Lymphatic disease is a class of disorders which directly affect the components of the lymphatic system.

Examples include Castleman's disease and lymphedema.

Diseases and disorder

Hodgkin's Disease/Hodgkin's Lymphoma

This is a type of cancer of the lymphatic system. It can start almost anywhere in the body. It is believed to be caused by HIV, Epstein-Barr Syndrome, age and family history. Symptoms include weight loss, fever, swollen lymph nodes, night sweats, itchy skin, fatigue, chest pain, coughing or trouble swallowing.

Non-Hodgkin's Lymphoma

Lymphoma is a usually malignant cancer. It is caused by the body producing too many abnormal white blood cells. It is not the same as Hodgkin's Disease. Symptoms usually include painless, enlarged lymph node or nodes in the neck, weakness, fever, weight loss, and anemia.

Lymphadenitis is an infection of the lymph nodes usually caused by a virus, bacteria or fungi. Symptoms include redness or swelling around the lymph node.

Lymphangitis

Lymphangitis is an inflammation of the lymph vessels. Symptoms usually include swelling, redness, warmth, pain or red streaking around the affected area.

Lymphedema

Lymphedema is the chronic pooling of lymph fluid in the tissue. It usually starts in the feet or lower legs. It's also a side-effect of some surgical procedures.

Lymphocytosis

Lymphocytosis is a high lymphocyte count. It can be caused by an infection, blood cancer, lymphoma, or autoimmune disorders that are accompanied by chronic swelling.

6% of non-Hodgkin lymphoma cases are mantle cell lymphoma. As of 2015, the ratio of males to females affected is about 4:1.

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 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.

Some studies have suggested a genetic predisposition to the proposed autoimmune response. Several infectious candidates have been associated with Kikuchi disease.

Many theories exist about the cause of KFD. Microbial/viral or autoimmune causes have been suggested. "Mycobacterium szulgai" and "Yersinia" and "Toxoplasma" species have been implicated. More recently, growing evidence suggests a role for Epstein-Barr virus, as well as other viruses (HHV6, HHV8, parvovirus B19, HIV and HTLV-1) in the pathogenesis of KFD. However, many independent studies have failed to identify the presence of these infectious agents in cases of Kikuchi lymphadenopathy. In addition, serologic tests including antibodies to a host of viruses have consistently proven noncontributory and no viral particles have been identified ultrastructurally.

KFD is now proposed to be a nonspecific hyperimmune reaction to a variety of infectious, chemical, physical, and neoplastic agents. Other autoimmune conditions and manifestations such as antiphospholipid syndrome, polymyositis, systemic juvenile idiopathic arthritis, bilateral uveitis, arthritis and cutaneous necrotizing vasculitis have been linked to KFD. KFD may represent an exuberant T-cell-mediated immune response in a genetically susceptible individual to a variety of nonspecific stimuli.

Human leukocyte antigen class II genes are more frequent in patients with Kikuchi disease, suggesting a genetic predisposition to the proposed autoimmune response.

A second regimen under evaluation is R-EPOCH (rituximab with etoposide-prednisone-vincristine-doxorubicin-cyclophosphamide), which demonstrated a 5-year progression-free survival (PFS) of 79% in a phase II trial. A phase III trial, CALGB 50303, is now comparing R-EPOCH with R-CHOP in patients with newly diagnosed DLBCL.

One area of active research is on separating patients into groups based on their prognosis and how likely they are to benefit from different drugs. Methods like gene expression profiling and next-generation sequencing may result in more effective and more personalized treatment.

T-PLL is an extremely rare aggressive disease, and patients are not expected to live normal lifespans. Before the recent introduction of better treatments, such as alemtuzumab, the median survival time was 7.5 months after diagnosis. More recently, some patients have survived five years and more, although the median survival is still low.

The diffuse leprosy of Lucio and Latapí, also known as diffuse lepromatous leprosy or "pretty leprosy" is a clinical variety of lepromatous leprosy. It was first described by Lucio and Alvarado in 1852 and re-identified by Latapí in 1936. It is common in Mexico (23% leprosy cases) and in Costa Rica and very rare in other countries.

James Cerhan and colleagues, try to determine genetic susceptibility that exists for this cancer by meta-analysis of three genome-wide association studies (GWAS). For this, a total of 3,857 cases and 7,666 controls were analyzed. This study is divided into three stages, which can differentiate into two phases:

– Discovery Phase: Stages 1 and 2.

– Phase replication: Stage 3.

Kikuchi-Fujimoto disease (KFD) is a rare, self-limiting disorder that typically affects the cervical lymph nodes. Recognition of this condition is crucial, especially because it can easily be mistaken for tuberculosis, lymphoma, or even adenocarcinoma. Awareness of this disorder helps prevent misdiagnosis and inappropriate treatment.

Kikuchi's disease is a very rare disease mainly seen in Japan. Isolated cases are reported in North America, Europe, and Asia. It is mainly a disease of young adults (20–30 years), with a slight bias towards females. The cause of this disease is not known, although infectious and autoimmune causes have been proposed. The course of the disease is generally benign and self-limiting. Lymph node enlargmeent usually resolves over several weeks to six months. Recurrence rate is about 3%. Death from Kikuchi disease is extremely rare and usually occurs due to liver, respiratory, or heart failure.

Primary mediastinal (thymic) large B-cell lymphoma, also called primary mediastinal large B-cell lymphoma (PMLBCL) and mediastinal large B-cell lymphoma, is a distinct type of diffuse large B-cell lymphoma involving the mediastinum, recognized in the WHO 2008 classification.

Multiagent chemotherapy is recommended, but the preferred regimen is controversial, as is consolidative radiotherapy.