Malignant neoplasms composed of MACROPHAGES or DENDRITIC CELLS. Most histiocytic sarcomas present as localized tumor masses without a leukemic phase. Though the biological behavior of these neoplasms resemble lymphomas, their cell lineage is histiocytic not lymphoid.

A rare, usually progressive disorder comprising an invasive proliferation of neoplastic HISTIOCYTES. Many previous cases are now thought to represent ANAPLASTIC LARGE-CELL LYMPHOMA.

Synonyms: Malignant Histiocytosis, Sarcoma, Histiocytic, Malignant Histiocytoses, True Histiocytic Lymphomas, Histiocytic Lymphoma, True, Histiocytic Sarcoma, Lymphoma, True Histiocytic, Histiocytosis, Malignant, True Malignant Histiocytoses, True Malignant Histiocytosis, Histiocytosis, True Malignant, Histiocytic Lymphomas, True, Sarcomas, Histiocytic, Malignant Histiocytoses, True, True Histiocytic Lymphoma, Lymphomas, True Histiocytic, Malignant Histiocytosis, True, Histiocytoses, True Malignant, Histiocytic Sarcomas, Histiocytoses, Malignant