T. Ishida et al., DEDIFFERENTIATED CHONDROSARCOMA OF THE RIB WITH A MALIGNANT MESENCHYMOMATOUS COMPONENT - AN AUTOPSY CASE-REPORT, Pathology international, 47(6), 1997, pp. 397-403
A rare variant of dedifferentiated chondrosarcoma with malignant mesen
chymomatous component in a 57-year-old male is reported. The patient p
resented with a posterior mediastinal mass arising from the left eight
h and ninth ribs showing well differentiated, low-grade chondrosarcoma
. Five years later, local recurrence occurred and an excised specimen
also showed the same histological features as the primary tumor. Anoth
er 6 years later, the tumor recurred and metastasized to the multiple
organs, the patient dying 4 months later. Autopsy revealed that the re
current and metastatic tumors showed malignant mesenchymomatous 'dedif
ferentiation' of chondrosarcoma composed of rhabdomyosarcoma, angiosar
coma, chondrosarcoma, osteosarcoma, and leiomyosarcoma, in addition to
fibrosarcomatous areas. Although the less differentiated component of
dedifferentiated chondrosarcoma usually shows the histological featur
es of malignant fibrous histiocytoma and fibrosarcoma, multilineage di
fferentiation can occur in that component. The phenomenon of 'dediffer
entiation' in chondrosarcoma and the relationship to and distinction f
rom malignant mesenchymoma of soft tissue and bone are discussed.