Immunohistochemistry with
antibodies to
calponin and h-
caldesmon was undertaken in
paraffin sections from 50
synovial sarcomas (19 biphasic and 31 monophasic, of which one biphasic and eight monophasic tumours had poorly differentiated areas), 10 each of malignant peripheral nerve sheath tumour (
MPNST), solitary fibrous tumour (SFT),
dermatofibrosarcoma (DFSP),
Ewing's sarcoma (ES/
PNET), and
neuroblastoma, eight
alveolar rhabdomyosarcomas, five adult
fibrosarcomas and five
carcinosarcomas. Nine of 19 biphasic
synovial sarcomas were positive for
calponin in spindle and glandular areas, nine in spindle cells only, and one in glands only. All monophasic
synovial sarcomas and poorly differentiated areas expressed
calponin; in monophasic tumours this was focally (29% of cases), moderately (39%), or diffusely (32%) positive and the poorly differentiated areas were usually moderately or diffusely positive. Four
synovial sarcomas showed focal reactivity for h-
caldesmon.
Calponin was found in 4/10
MPNST, 7/10 SFT, 4/10 DFSP, 3/5
fibrosarcomas and the spindle component of the
carcinosarcomas. H-
caldesmon was weakly positive in 1/10
MPNST, 4/10 SFT, 0/10 DFSP, 0/5
fibrosarcomas and 1/5
carcinosarcomas (glands only). Both markers were negative in the other small round cell tumours.
CONCLUSIONS: