AN EXTENSIVE review of the literature on dermoid cysts and teratomas of the mediastinum was made by Rusby1, who estimated that 245 cases had been reported up to the end of 1939. An analysis of the cases collected by Rusby indicates that of the patients with dermoid cyst and teratoma of the mediastinum which I have operated on there are 4 who present unusual features.
Rusby stated that it was extremely rare for a dermoid cyst to have a prolongation which extended through the hilus and into the lung and, therefore, to be regarded as partly intrapulmonary. Apparently none of the dermoid cysts which Rusby found described in the literature manifested this type of intrapulmonary extension, but he cited personal communication from Roberts referring to such a case. One of my patients had a dermoid cyst which extended from the mediastinum through the hilus of the upper lobe of