[Localised swelling of a child's leg is not always harmless]

Soft tissue swelling of the leg is a relatively uncommon occurrence in children, and is often benign. In adults, 1% of malignancies originate in soft tissue, whereas for children the figure is 8%. Based on medical history and physical examination alone, it is difficult to differentiate between benign and malignant soft tissue tumours.

A 15-year-old girl presented to her GP with a swelling in the left thigh, without alarming symptoms. The GP suspected the lesion to be benign and she was asked to return if the swelling increased in size. Five months later, when the lesion was excised, it proved to be a granular cell tumour. The second case concerns a 12-year-old boy who presented to his GP with a swelling of the lateral malleolus, which had developed after impact against a door five years ago. The boy was referred to the surgical department where after excision it was shown to be a dermatofibrosarcoma protuberans.

In paediatric cases when diagnosis is inconclusive, including cases involving possible growth of the swelling, suspicions raised during physical examination, or unusually lengthy recovery after trauma, awareness is important. Imaging diagnostics or even tissue excision with histopathology may be indicated to allow the correct diagnosis to be made.