[Orbital rhabdomyosarcoma in children. Apropos of 2 cases].

Rhabdomyosarcoma accounts for 5% of childhood malignant tumours; in 10% it occurs in the orbit where it is the most frequent malignant tumour. Rhabdomyosarcoma is a mesenchymatous tumour with striated muscular differentiation. However, this myogenous differentiation is sometimes undiscernable on standard histological examination and requires immunohistochemical and ultrastructural studies to be shown. Treatment depends on the assessment of local extension, principally based on tomodensitometry. When the tumour is limited to the orbit, survival rate may reach 100% with todays therapeutic protocols. When the orbital walls are invaded the tumour is parameningeal and recovery can only be achieved by increasing chemotherapy at the cost of long-term side effects. Hence, this tumour must be diagnosed and treated very early. The authors report two cases of rhabdomyosarcoma dealing with the two main histological forms of the tumour and with their evolutive risks.