[Mediastinal fibrosis associated with Riedel's thyroiditis. Apropos of a case].

The authors describe a case of mediastinal fibrosis in a 53 year old woman which presented with a superior venacaval syndrome ten years after the diagnosis of a Riedel's thyroiditis. The clinical and laboratory evidence did not reveal anything to suggest other fibrosing disorders (such as retroperitoneal fibrosis, extra-hepatic biliary fibrosis or orbital fibrosis) which could be associated either simultaneously or successively with this multi-focal fibrosis. The physiology of this disorder currently remains imprecise. A current hypothesis is that there is an immunological reaction in the periarterial area leading to lipid components make atheromatous plaques. The therapeutic means are limited and depend on the localisation of the fibrous tissue and of their functional repercussions. Currently, the benefit of corticosteroids on the mediastinal fibrotic lesions has not been demonstrated.