Murine model for skeletal metastases of Ewing's sarcoma

Ewing's sarcoma shows a strong tendency to metastasize to the lungs or the skeleton, or both. A peculiar feature of the secondary involvement of bone with this tumor is that it may also appear in the absence of clinically evi dent lung metastases, both at clinical presentation and during the course o f the disease. Although osseous metastases are critically relevant for prog nosis, the pathogenesis of this peculiar feature of Ewing's sarcoma is poor ly understood, partly due to the lack of appropriate experimental in vivo m odels. We show that the intravenous injection of TC-71 Ewing's sarcoma cell s into athymic 4-5-week-old Crl/nu/nu (CD-1) BR mice reproducibly colonizes specific sites of the skeleton in addition to the lungs and lymph nodes. T he distribution and the morphologic appearance of these experimental bone m etastases mimic the pattern of skeletal involvement observed in humans. Thi s experimental model of bone metastasis of Ewing's sarcoma may be the basis for future studies aimed at understanding the pathophysiology and treatmen t of Ewing's sarcoma.