Mediastinal masses in childhood: a review from a paediatric pathologist's point of view.

From 1970 to 1989, 121 children with mediastinal masses of various sorts were seen in the Department of Pathology, Royal Children's Hospital, Melbourne. The series is considered representative of the true incidence of these conditions in the state of Victoria, which had an average paediatric population during the time of this series of 900,000 children. The commonest cause of a mediastinal mass was NHL (36 cases). This was followed by HD (24 cases), then neuroblastoma and ganglioneuroma (16 and 9 cases respectively), duplication cysts (10 cases), teratomas (7 cases), neurofibroma (4 cases) and lymphangioma (3 cases). A great variety of rare conditions made up the remainder of the series and included mediastinal abscess, thymic cyst, pericardial cyst, accessory lobe of lung, plasma cell granuloma, fibromatosis, paravertebral Ewing's tumour, carcinoid tumour and neurofibrosarcoma. Presentation of the children with NHL was often acute with respiratory distress, while the child with HD was usually older and symptoms were more often systemic than local. The surgeon's role in diagnosis of these most frequently encountered mediastinal masses can be crucial and biopsy when indicated must be carried out with great care to produce material that is adequate for diagnosis and for the performance of cell marker studies and chromosome analysis. Neuroblastoma (NBL) and ganglioneuroma (GN) together were the third largest group. Children with neuroblastoma were usually young; 15 of the 18 cases were less than 2 years old. One-third of the infants with neuroblastoma presented with paraplegia and one-third with respiratory symptoms including wheeze, stridor and respiratory difficulty. Three children had Horner's syndrome. Prognosis of children with thoracic neuroblastoma is very good and contrasts with the poor outlook for those with abdominal neuroblastoma. Stage at presentation is probably the most important single prognostic variable. Ganglioneuroma presents at a later age than neuroblastoma and symptoms may be present for a long time or may be completely absent. Catecholamines, usually raised in neuroblastoma, are mostly normal in ganglioneuroma. Duplication cysts were the next most frequent group. Symptoms can often be acute and life threatening, although in three of our ten cases the cyst was an incidental finding on chest X-ray. However, only three of our patients had a normal respiratory examination. Teratomas were usually large and more often benign than malignant. Excision is the mandatory treatment and is usually curative. Although teratomas in young infants are often cellular and composed of many immature tissue types, their behaviour is benign.(ABSTRACT TRUNCATED AT 400 WORDS)