malignant giant cell tumor of tendon sheath
Although similar in initial histology to tenosynovitis, these very rare tumors appear more aggressive at the time of recurrence and may metastasize.
Such recurrences resemble the aggressive bone tumor and tend to have fewer multinucleated giant cells, rnore tightly compact mononuclear cells arranged in sheets, and a high mitotic rate (more than 10 mitoses per 20 high-power fields).
Synopsis
Rare tumor with coexisting or prior benign giant cell tumor plus sarcomatous areas
Not a WHO diagnosis
Mean 61 years, no gender preference
Usually extra-articular, near large joints or extremities
Often metastasizes or recurs, but variable outcome.
Mean 9 cm
Benign areas with gradual or abrupt change to frank sarcoma containing pleomorphic, spindle or enlarged oval cells resembling MFH, fibrosarcoma, myxosarcoma or giant cell tumor with large nuclei and prominent nucleoli (AJSP 1997;21:153)
Also necrosis
Atypical mitotic figures
Benign and malignant areas
Molecular cytogenetics
trisomy 5
trisomy 7 (Archives 2000;124:1636)
See also
giant cell tumor of tendon sheath (GCTTS)
- localized giant cell tumor of tendon sheath (GCTTS, focal type)
- diffuse giant cell tumor of tendon sheath (GCTTS, diffuse type)