Malignant histiocytosesC96.8

Basically, the spectrum of malignant histiocytoses (MH) can be divided into:

• primary malignant histiocytoses (manifest primarily in the skin)
• and
• secondary malignant histiocytoses (manifest primarily extracutaneously and secondarily affect the integument).

can be subdivided.

• Langerhans cell leukemia
• Langerhans cell sarcoma (LZS)

Individual reports have documented identical immunoglobulin gene rearrangements suggesting a common clonal origin for both histiocytic/dendritic cell sarcoma sarcoma and B-cell neoplasm. Langerhans cell sarcoma is characterized by pleomorphic cytology, a high mitotic rate, and characteristic immunohistochemical staining for langerin, S100, and CD1a.

Phenotypic histological analysis (cells express markers of macrophages and/or Langerhans cells). Malignancies with B-cell differentiation are still to be excluded, as is "sarcoma of interdigitating dendritic cells".

With increasingly refined histological, immunological and molecular biological methods, it is now possible to assign many malignancies previously classified as malignant histiocytoses to T- or B-cell lymphomas. Especially anaplastic large cell CD30-positive T-cell lymphoma (historical name: atypical regressive histiocytosis) falls into this category. Severe cases of hemophagocytic lymphohistiocytosis (HLH) were also previously interpreted as malignant histiocytoses.

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