We describe a 12-year-old patient with a primary pulmonary mass in the left upper lung. The diagnosis of inflammatory pseudotumour was suspected preoperatively. After pathological examination and complete clinical evaluation, a diagnosis of malignant primary pulmonary fibrous histiocytoma was established. This is a very uncommon primary neoplasm of the lung and to our knowledge only five paediatric cases have been reported. Because of the rarity of these sarcomas and histological similarities to benign inflammatory pseudotumour, care must be taken to avoid confusion between the two disorders particularly in intra-operative frozen sections.
Conclusion: Primary malignant fibrous histiocytoma of the lung is an uncommon tumour that should be considered in the differential diagnosis of pulmonary neoplasms of childhood. The histological diagnosis can be difficult due to the similarities with inflammatory pseudotumour.