Secondary localisation of an intra-thoracic benign mesenchymoma in the fossa poplitea: a rare paediatric case.

Thymomas are tumours that rarely occur in children, are almost invariably benign, and are usually discovered incidentally in the anterior mediastinum on chest X-rays. Whereas in adults these tumours are often associated with myasthenia gravis and other autoimmune diseases, this occurrence is very rare in the paediatric population. Multiple localisation and/or extra-thoracic recurrence of thymomas in children also appears to be exceptional with no reported cases in the English literature. We report one rare paediatric case.