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Cavitation of a mediastinal mass following chemotherapy for histiocytosis-X: CT demonstration.

A recurrent mediastinal mass, believed to be thymus, in an infant with classic idiopathic histiocytosis-X underwent massive cavitation following chemotherapy. Both the mass and cavitation resolved. The exact nature of development of air inside the mass is not known but communication with the airways or airspaces of the lungs is suspected.