Histiocytic sarcoma is a tumor derived from histiocytes.[1]
They are often positive for CD163.[2]
It can appear in the thyroid.[3]
Fibroma/fibrosarcoma: Dermatofibrosarcoma · Dermatofibrosarcoma protuberans · Desmoplastic fibroma
general: Myoma/myosarcoma
smooth muscle: Leiomyoma/leiomyosarcoma