Extraskeletal myxoid chondrosarcoma
Clinical features
This
is a rare malignant tumour of deep tissues of the proximal
extremities and limb girdles of middle-aged adults. It accounts for
2.5% of soft tissue sarcomas.
Histopathology
There is a
multinodular growth pattern. Primitive chondroid cells form a
lacelike arrangement within an abundant myxoid matrix. There may be
cellular ares showing epithelioid or rhabdoid cells and nuclear
pleomorphism. Chondroitin-4 and 6-sulphate are present.
Immunohistochemistry
Ultrastructure
There is
ultrastructural evidence of chondroid differentiation. Neural and
neuroendocrine differentiation has also been reported. Some cases
show long parallel microtubules within rough endoplasmic reticulum.
Cytogenetics
75%
of cases have a translocation, t(9;22)(q22;q12) resulting in the
fusion of the EWS gene and the CHN gene. Other cases show
t(9;17)(q22;q11.2), resulting in a TAF2N-CHN fusion product.
Differential diagnosis
-
intramuscular myxoma
nerve
sheath myxoma / neurothekeoma
extraskeletal
chondroma
myoepithelioma
of soft parts: positive for actin, cytokeratins and EMA
parachordoma:
positive for cytokeratins and EMA
metastatic
adenocarcinoma
myxoid
liposarcoma
low-grade
myxofibrosarcoma / myxoid MFH
epithelioid
sarcoma
MPNST
skeletal
or extraskeletal chondrosarcoma with prominent myxoid change
Prognosis
It
has a prolonged indolent course with a high rate of local recurrence
and distant metastases, often causing late deaths. Adverse prognostic
factors are large tumour size, proximal tumour location, older patient
and the presence of metastases. The prognostic significance of
cellularity, mitotic rate, pleomorphism, and the presence of
epithelioid and rhabdoid cells is disputed.
References
1Okamoto,
S., Hisaoka, M., Ishida, T., Imamura, T., Kanda, H., Shimajiri, S.,
Hashimoto, H. Extraskeletal myxoid chondrosarcoma: a
clinicopathologic, immunohistochemical, and molecular analysis of 18
cases. Human Pathol 2001;32:1116-1124.
2Oliveira,
A. M., Sebo, T. J., McGrory, J. E., Gaffey, T. A., Rock, M. G.,
Nascimento, A. G. Extraskeletal myxoid chondrosarcoma: a
clinicopathologic, immunohistochemical, and ploidy analysis of 23
cases Mod Pathol 2000;13:900-908.
3Harris,
M., Coyne, J., Tariq, M., Eyden, B. P., Atkinson, M., Freemont, A.
J., Varley, J., Attwooll, C., Telford, N. Extraskeletal myxoid
chondrosarcoma with neuroendocrine differentiation: a pathologic,
cytogenetic, and molecular study of a case with a novel translocation
t(9;17)(q22;q11.2). Am J Surg Pathol 2000;24:1020-1026.
4Cummings,
T. J., Shea, C. R., Reed, J. A., Burchette, J. L., Prieto, V. G.
Expression of the intermediate filament peripherin in extraskeletal
myxoid chondrosarcoma. Cutan Pathol 2000;27:141-146
This page last
revised 24.12.2001.