Thoracic mesenchymoma of infancy.

Mesenchymoma of the chest wall is rare in infancy and can be easily mistaken for a malignant tumor. It is a distinct pathological entity that presents at birth or during infancy as self-limiting expansile intraosseous lesions involving the body of one or more ribs. Histologically, it is a benign focal overgrowth of normal skeletal elements. Two such cases are presented.