Unusual Presentation of Fibrosarcoma in a Child.

Malignant soft tissue tumours are rare in infants. Specific radiologic features help differentiate benign from malignant musculoskeletal entities. We report a case of malignant soft tissue tumour with initial radiologic evaluation suggesting a benign entity, thus delaying diagnosis. The case was treated as a case of cystic hygroma, suggested by ultrasound and MRI with good initial response to bleomycin injection. Later, symptoms recurred with poor response to repeat therapy which led to review the diagnosis. Angiography, arterial embolisation, surgical excision, and finally histopathology showed that a cystic infantile fibrosarcoma was initially misinterpreted as cystic hygroma. A comprehensive literature review and discussion on infantile fibrosarcoma; and its mimics are provided.