This is a condition of adults with a wide age range. It is somewhat more common in women. Some patients have multiple lesions. The lesion presents as a slowly growing painless mass, most often proximally on extremities. Most are deep (subfascial, intramuscular or deeper): a few are superficial (subcutaneous or suprafascial). About 50% of cases are intramuscular.
Macroscopic appearances
There is microscopic infiltration at the margins. In most cases, some areas closely resemble intramuscular myxoma, but there are always more cellular and hypervascular areas. Even in the most cellular areas, pleomorphism, hyperchromasia and mitotic activity are lacking. There is no perivascular condensation of tumour cells.
|
17/30 |
|
|
3/30 |
|
|
0/30 |
|
|
0/30 |
|
intramuscular myxoma is less cellular
juxta-articular myxoma occurs in proximity to joints but is not histologically distinguishable: recurrence is more common.
low-grade myxofibrosarcoma shows pleomorphism and curvilinear vessels
myxoid liposarcoma shows lipoblasts and crows-foot vasculature
low-grade fibromyxoid sarcoma is diffusely more cellular with alternating myxoid and collagenous zones.
myxoid neurofibroma shows intralesional nerve fibres and are S-100 positive.
myxoid malignant peripheral nerve sheath tumour show mitoses, variable pleomorphism and perivascular condensation of tumour cells. Up to 50% of cases are S-100 positive.
Behavior is benign to date, with a low risk of recurrence if incompletely excised.
This page last revised 21.12.2001.