[Diagnostic strategy in pediatrics soft tissue sarcomas]

Soft tissue sarcomas in children are rare tumor, representing around 6 to 7% of children cancer. They spread mostly sporadically (90%) and therefore are rarely associated to an underlying constitutional genetic disease (10%). About half of those sarcomas are rhabdomyosarcomas and the others are a very heterogenous histologic group with various bio-pathologies and prognosis. Clinical presentation is mainly a soft tissue lump often difficult to distinguish from more frequent benign causes (malformative, infectious, benign, or pseudotumor). Inappropriate initial diagnosis work-up has a strong impact on soft tissue sarcomas' prognosis. Adapted complementary investigations (first ultrasound and MRI) are important to compile arguments for a malign origin and to indicate a biopsy. However, predictive value of imaging exams still remains imperfect, and histological analysis by percutaneous image-guided biopsy and sometimes by surgical biopsy is often necessary. Authors realize an update on optimal diagnostic pathway including molecular tests in presence of a soft tissue mass in a child.