A histiocytoma is a tumour consisting of histiocytes.

[1] Histiocytes are cells that are a part of the mononuclear phagocytic system, a part of the body's immune system that consists of phagocytic cells, which are responsible for engulfing solid particles by the cell membrane to form an internal phagosome by phagocytes and protists.

Myxofibrosarcoma had been classified as a type of histiocytoma.

However, the World Health Organization (2020) reclassified myxofibrosarcoma as a malignant tumor in the category of fibroblastic/myofibroblastic tumors.

[2] Types include: