An 11 year old female noticed weakness of her facial muscles, drooping eyelids and general asthenia which initially responded to prostigmine - features characteristic of myasthenia gravia. The specimen was obtained at autopsy after sudden collapse and death of the patient.
The specimen is a pale lobulated tumour plaque 7 cm in diameter, resting on parietal pericardium and attached to the middle lobe of the right lung. The lung, which has been folded back from the tumour to which it was attached, appears to have been infiltrated. Histologically this is a malignant thymoma.