PTLD may spontaneously regress on reduction or cessation of immunosuppressant medication, and can also be treated with addition of anti-viral therapy. In some cases it will progress to non-Hodgkin's lymphoma and may be fatal. A phase 2 study of adoptively transferred EBV-specific T cells demonstrated high efficacy with minimal toxicity.

Guidelines for management of patients up to 18 years with Langerhans cell histiocytosis has been suggested. Treatment is guided by extent of disease. Solitary bone lesion may be amenable through excision or limited radiation, dosage of 5-10 Gys for children, 24-30 Gys for adults. However systemic diseases often require chemotherapy. Use of systemic steroid is common, singly or adjunct to chemotherapy. Local steroid cream is applied to skin lesions. Endocrine deficiency often require lifelong supplement e.g. desmopressin for diabetes insipidus which can be applied as nasal drop. Chemotherapeutic agents such as alkylating agents, antimetabolites, vinca alkaloids either singly or in combination can lead to complete remission in diffuse disease.

Treatment with chemotherapy has been used with some success, particularly using lomustine, prednisone, doxorubicin, and cyclophosphamide. Because of the rapid progression of this aggressive disease, the prognosis is very poor.

Most histiocytomas will regress within two or three months. Surgical removal may be necessary if the tumor does not regress or if it is growing rapidly to a large size. Histiocytomas should never be treated with an intralesional injection of a corticosteroid, as remission relies on recognition of the tumour by the body's immune system which is suppressed by steroids.

In secondary cases, treatment of the cause, where possible, is indicated. Additionally, treatment for HLH itself is usually required.

While optimal treatment of HLH is still being debated, current treatment regimes usually involve high dose corticosteroids, etoposide and cyclosporin. Intravenous immunoglobulin is also used. Methotrexate and vincristine have also been used. Other medications include cytokine targeted therapy.

An experimental treatment, an anti IFN-gamma monoclonal antibody tentatively named NI-0501, is in clinical trials for treating primary HLH. The FDA awarded breakthrough drug status to NI-0501 in 2016.

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

Natural killer (NK) cell therapy is used in pediatrics for children with relapsed lymphoid leukemia. These patients normally have a resistance to chemotherapy, therefore, in order to continue on, must receive some kind of therapy. In some cases, NK cell therapy is a choice.

NK cells are known for their ability to eradicate tumor cells without any prior sensitization to them. One problem when using NK cells in order to fight off lymphoid leukemia is the fact that it is hard to amount enough of them to be effective. One can receive donations of NK cells from parents or relatives through bone marrow transplants. There are also the issues of cost, purity and safety. Unfortunately, there is always the possibility of Graft vs host disease while transplanting bone marrow.

NK cell therapy is a possible treatment for many different cancers such as Malignant glioma.

The basis of management is to find and correct the underlying cause. Many times cats with EGC will respond to treatment with corticosteroids or to ciclosporin.

Investigators at the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health currently have clinical protocols to study new approaches to the diagnosis and treatment of this disorder.

Selection of biological targets on the basis of their combinatorial effects on the leukemic lymphoblasts can lead to clinical trials for improvement in the effects of ALL treatment. Tyrosine-kinase inhibitors (TKIs), such as Imatinib, are often incorporated into the treatment plan for patients with "Bcr-Abl1+ (Ph+)" ALL. However, this subtype of ALL is frequently resistant to the combination of chemotherapy and TKIs and allogeneic stem cell transplantation is often recommended upon relapse.

Blinatumomab, a CD19-CD3 bi-specific monoclonal murine antibody, currently shows promise as a novel pharmacotherapy. By engaging the CD3 T-cell with the CD19 receptor on B cells, it triggers a response to induce the release of inflammatory cytokines, cytotoxic proteins and proliferation of T cells to kill CD19 B cells.

Chimeric antigen receptors (CARs) have been developed as a promising immunotherapy for ALL. This technology uses a single chain variable fragment (scFv) designed to recognize the cell surface marker CD19 as a method of treating ALL.

CD19 is a molecule found on all B-cells and can be used as a means of distinguishing the potentially malignant B-cell population. In this therapy, mice are immunized with the CD19 antigen and produce anti-CD19 antibodies. Hybridomas developed from mouse spleen cells fused to a myeloma cell line can be developed as a source for the cDNA encoding the CD19 specific antibody. The cDNA is sequenced and the sequence encoding the variable heavy and variable light chains of these antibodies are cloned together using a small peptide linker. This resulting sequence encodes the scFv. This can be cloned into a transgene, encoding what will become the endodomain of the CAR. Varying arrangements of subunits serve as the endodomain, but they generally consist of the hinge region that attaches to the scFv, a transmembrane region, the intracellular region of a costimulatory molecule such as CD28, and the intracellular domain of CD3-zeta containing ITAM repeats. Other sequences frequently included are: 4-1bb and OX40. The final transgene sequence, containing the scFv and endodomain sequences is then inserted into immune effector cells that are obtained from the patient and expanded "in vitro". In trials these have been a type of T-cell capable of cytotoxicity.

Inserting the DNA into the effector cell can be accomplished by several methods. Most commonly, this is done using a lentivirus that encodes the transgene. Pseudotyped, self-inactivating lentiviruses are an effective method for the stable insertion of a desired transgene into the target cell. Other methods include electroporation and transfection, but these are limited in their efficacy as transgene expression diminishes over time.

The gene-modified effector cells are then transplanted back into the patient. Typically this process is done in conjunction with a conditioning regimen such as cyclophosphamide, which has been shown to potentiate the effects of infused T-cells. This effect has been attributed to making an immunologic space within which the cells populate. The process as a whole results in an effector cell, typically a T-cell, that can recognize a tumor cell antigen in a manner that is independent of the major histocompatibility complex and which can initiate a cytotoxic response.

In 2017 tisagenlecleucel was approved by the FDA as a CAR-T therapy for acute B-cell lymphoblastic leukaemia patients who did not respond adequately to other treatments or have relapsed. In a 22-day process, the "drug" is customized for each patient. T cells purified from each patient are modified by a virus that inserts genes that encode a chimaeric antigen receptor into their DNA, one that recognizes leukemia cells.

Current treatment options include:

- Surgical debulking

- High-dose Corticosteroid therapy

- Cyclosporin

- Interferon-α

- Chemotherapy

- Vemurafenib. It would appear that approximately half these patients harbor point mutations of the BRAF gene at codon 600 substituting the amino acid glutamine for valine. Vemurafenib, an oral FDA approved targeted agent to the BRAF protein for melanoma, shows dramatic activity in patients Erdheim–Chester disease whose tumor contains the same mutation. In 2017 the US FDA approved vemurafenib for this indication.

- Radiation therapy

All current treatments have had varying degrees of success.

The vinca alkaloids and anthracyclines have been used most commonly in ECD treatment.

Some patients have no symptoms, spontaneous remission, or a relapsing/remitting course, making it difficult to decide whether therapy is needed. In 2002, authors from Sapienza University of Rome stated on the basis of a comprehensive literature review that "clinical observation without treatment is advisable when possible."

Therapeutic options include surgery, radiation therapy, and chemotherapy. Surgery is used to remove single lymph nodes, central nervous system lesions, or localized cutaneous disease. In 2014, Dalia and colleagues wrote that for patients with extensive or systemic Rosai–Dorfman disease, "a standard of care has not been established" concerning radiotherapy and chemotherapy.

ANKL is treated similarly to most B-cell lymphomas. Anthracycline-containing chemotherapy regimens are commonly offered as the initial therapy. Some patients may receive a stem cell transplant.

Most patients will die 2 years after diagnosis.

The treatment a child will undergo is based on the child's age, overall health, medical history, their tolerance for certain medications, procedures, and therapies, along with the parents' opinion and preference.

- Chemotherapy is a treatment that uses drugs to interfere with the cancer cells ability to grow and reproduce. Chemotherapy can be used alone or in combination with other therapies. Chemotherapy can be given either as a pill to swallow orally, an injection into the fat or muscle, through an IV directly into the bloodstream, or directly into the spinal column.

- A stem cell transplant is a process by which healthy cells are infused into the body. A stem-cell transplant can help the human body make enough healthy white blood cells, red blood cells, or platelets, and reduce the risk of life-threatening infections, anemia, and bleeding. It is also known as a bone-marrow transplant or an umbilical-cord blood transplant, depending on the source of the stem cells. Stem cell transplants can use the cells from the same person, called an autologous stem cell transplant or they can use stem cells from other people, known as an allogenic stem cell transplant. In some cases, the parents of a child with childhood leukemia may conceive a saviour sibling by preimplantation genetic diagnosis to be an appropriate match for the HLA antigen.

The prognosis is guarded with an overall mortality of 50%. Poor prognostic factors included HLH associated with malignancy, with half the patients dying by 1.4 months compared to 22.8 months for non-tumour associated HLH patients.

Secondary HLH in some individuals may be self-limited because patients are able to fully recover after having received only supportive medical treatment (i.e., IV immunoglobulin only). However, long-term remission without the use of cytotoxic and immune-suppressive therapies is unlikely in the majority of adults with HLH and in those with involvement of the central nervous system (brain and/or spinal cord).

Most patients with "ETV6-ACSL6"-related disease present with findings similar to eosinophilia, hypereosinophila, or chronic eosinophilic leukemia; at least 4 cases presented with eosinophilia plus findings of the red blood cell neoplasm, polycythemia vera; three cases resembled acute myelogenous leukemia; and one case presented with findings of a combined Myelodysplastic syndrome/myeloproliferative neoplasm. Best treatments for "ETV6-ACSL6"-related disease are unclear. Patients with the polycythemia vera form of the disease have been treated by reducing the circulating red blood cell load by phlebotomy or suppressing red blood cell formation using hydroxyurea. Individual case studies report that "ETV6-ACSL6"-associated disease is insensitive to tyrosine kinase inhibitors. Best treatment currently available, therefore, may involve chemotherapy and bone marrow transplantion.

The disease is an uncontrolled proliferation of B cell lymphocytes latently infected with Epstein-Barr virus. Production of an interleukin-10, an endogenous, pro-regulatory cytokine, has also been implicated.

In immunocompetent patients, Epstein-Barr virus can cause infectious mononucleosis in adolescents, which is otherwise asymptomatic in children during their childhood. However, in immunosuppressed transplant patients, the lack of T-cell immunosurveillance can lead to the proliferation of these EBV-infected of B-lymphocytes.

However, calcineurin inhibitors (tacrolimus and ciclosporin), used as immunosuppressants in organ transplantation inhibit T cell function, and can prevent the control of the B cell proliferation.

Depletion of T cells by use of anti-T cell antibodies in the prevention or treatment of transplant rejection further increases the risk of developing post-transplant lymphoproliferative disorder. Such antibodies include ATG, ALG and OKT3.

Polyclonal PTLD may form tumor masses and present with symptoms due to a mass effect, e.g. symptoms of bowel obstruction. Monoclonal forms of PTLD tend to form a disseminated malignant lymphoma.

Langhans cells are often found in transbronchial lung biopsies or lymph node biopsies in patients suffering from sarcoidosis.

Langhans giant cells are named after Theodor Langhans (1839–1915), a German pathologist.

They should not be confused with Langerhans cells, which are mononuclear epidermal dendritic cells derived (like Langhans cells) from monocytes and named after Paul Langerhans. (The Islets of Langerhans are also named after Paul Langerhans.)

Patients with hematological disease related to the cited "FLT3" fusion genes present with either a myeloid or lymphoid neoplasm plus eosinophilia. Four of 6 patients with "ETV6-FLT3"-related disease, a patient with "GOLGB1-FLT3"-related disease, and a patient with "TRIP11-FLT3"-related disease presented with findings similar to T-cell lymphoma while a patient with "SPTBN1-FLT3"-related disease had findings of chronic myelogenous leukemia. Two patients with "ETV6-FLT3"-related disease experienced complete hematologic remissions when treated with a multi-kinase inhibitor, sunitinib, that has inhibitory activity against FLT3 protein. However, these remissions were short-lived. A third patient with "ETV6-FLT3"-related disease was treated with a similarly active kinase inhibitor, sorafenib. This patient achieved a complete hematological response and was then given a hematopoietic stem cell transplantation. The latter treatment regimen, FLT3 inhibitor followed by hematopoietic stem cell transplantation, may be the best approach currently available for treating "FLT3"-releated hematological disease.

Langerhans cells are dendritic cells (antigen-presenting immune cells) of the skin and mucosa, and contain organelles called Birbeck granules. They are present in all layers of the epidermis and are most prominent in the stratum spinosum. They also occur in the papillary dermis, particularly around blood vessels, as well as in the mucosa of the mouth, foreskin, and vagina. They can be found in other tissues, such as lymph nodes, particularly in association with the condition Langerhans cell histiocytosis (LCH).

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.

Interdigitating dendritic cell sarcoma is a form of malignant histiocytosis affecting dendritic cells.

It can present in the spleen. It can also present in the duodenum.

X-type histiocytoses are a clinically well-defined group of cutaneous syndromes characterized by infiltrates of Langerhans cells, as opposed to Non-X histiocytosis in which the infiltrates contain monocytes/macrophages. Conditions included in this group are: