Teaching Case

Chest pain

Right sided pleuritic chest pain

8 – 15% of patients with Myasthemia gravis have a thymoma 50% of these are malignant. Usually found in the anterior mediastinum. RADIOLOGICAL INVESTIGATIONS : -Plain radiographs: frontal and lateral views. -CT -MRI The tumour can be very large (1 – 10cm in diameter), and usually replaces the normal thymus. Variable density from fat to soft tissue; calcification often visible. Cystic components may be present. Can be benign / malignant. Features of malignancy: Certain CT / MR findings are strongly suggestive:- Definite extension / spread of tumour into the mediastinum or lung parenchyma through breach in the capsule. -Pleural deposits from transpleural seeding of the tumour (especially posteriorly and in the costo-phrenic angles). -Irregular pericardial thickening from pericardial implants. Benign thymoma - No reliable radiological signs of benignity. -A low-density plane of cleavage, representing fat between tumour and mediastinal structures (debatable). -Size of tumour does not assist in diagnosing benignity. -Calcification, although suggestive, but not sine qua non that thymoma is benign. Conditions associated with thymomas: -Myasthenia gravis -Red blood cell aplasia -Hypogammaglobulinaemia -Mega oesophagus -Collagen vascular disease Other thymic tumours (difficult to differentiate) -Hodgkin’s disease -Teratomas -Germinal tumours -Primary carcinoid tumours -Congenital cysts.