NCIt definition : A benign fibroblastic neoplasm composed of uniform spindle cells with abundant fibromyxoid
stroma and a prominent network of innumerable branching, thin-walled blood vessels.
It typically arises in the extremities, mainly the legs, frequently involving or adjacent
to large joints such as the knee. Unusual anatomical locations include the back, abdominal
wall, pelvic cavity, and breast. The tumors are often subcutaneous but may be intramuscular
and deep. The lesion presents most often as a slow-growing painless mass. (WHO 2020);