Langerhans cell sarcoma (LCS) is a rare form of malignant histiocytosis. It should not be confused with Langerhans cell histiocytosis, which is cytologically benign. It can present most commonly in the skin and lymphatic tissue, but may also present in the lung, liver, and bone marrow. Treatment is most commonly with surgery or chemotherapy. Classification
Dendritic cell neoplasms are classified by the World Health Organization as follows:
Langerhans cell histiocytosis
Langerhans cell sarcoma
Interdigitating dendritic cell sarcoma/tumor
Follicular dendritic cell sarcoma/tumor
Dendritic cell sarcoma

Epidemiology
The exact incidence of LCS is unknown due to the rarity of the condition. The related condition, Langerhans Cell Histiocytosis (LCH) is estimated to have an incidence of around 5 cases per 1 million people per year. In one review of Japanese patients with confirmed LCS, patients were a median age of 41 years. Patients were twice as likely to be female than male. In another systematic review, the median age of presentation was 50 years, but with a slight predilection for males. Pathophysiology
Throughout the body in locations such as mucous membranes, skin, lymph nodes, thymus, and spleen are cells known as antigen-presenting cells. These cells are surveillance cells that take foreign antigens and present them to antigen-processing cells, such as T-cells, protecting the body from potential harm. Antigen-presenting cells are also termed Dendritic cells, of which Langerhans cells are a subtype. There are four main types that make up the structure and functions of lymphoid tissue, such as lymph nodes and splenic tissue.
When the LCS tumor is readily accessible, the best treatment method is usually surgical removal. There is, however, an observed increased risk of tumor relapse following surgical resection. Both chemotherapy and radiation therapy are useful as treatments, either as monotherapy or in conjunction with other treatments. Chemotherapy is currently the most common treatment method, either alone or in combination. The most common chemotherapeutic regimen consisted of cyclophosphamide, doxorubicin, vincristine, and prednisolone (otherwise known as CHOP therapy). Other common chemotherapeutic regimens include MAID (mesna, doxorubicin, ifosfamide, and dacarbazine), ESHAP (etoposide, carboplatin, cytarabine, and methylprednisolone), EPIG (etoposide, cisplatin, ifosfamide, mesna, and gemcitabine), and AIM (doxorubicin, ifosfamide, and mesna). Other regimens have been used with mixed levels of success. In an effort to prevent recurrence, sometimes combination therapy is used. Following surgical resection, additional radiation therapy or chemotherapy may be performed to prevent relapse. Patients receiving combined chemotherapy and radiation therapy has only shown limited benefit.There are a variety of other therapies under research with varying levels of reported success. These include high-dose chemotherapy, bone marrow transplants,  and somatostatin analogues.When there is only one site of LCS involvement, monotherapy may be sufficient treatment. But when the disease has multiple sites or has metastasized, combination therapy will be necessary to achieve any level of adequate treatment. Prognosis
Overall prognosis of patients with LCS depends heavily on the bodily organ involved and the extent of involvement of the tumor. Organs associated with a poor prognosis include the liver, lungs, and bone marrow.