Thymus Hyperplasia (Differential Diagnosis as before)

metu_12a_n.jpg: Drawings of different opacities in the anterior mediastinum which may be caused by a large thymus of different shapes and sites in the newborn. A physiologically large thymus may simulate a tumor of the anterior mediastinum in the newborn and young infant. White = heart shadow, black = thymus. The size, shape and site of the thymus is very variable. Not all limits of the individual thymus are depicted completely because the organ is superimposed by the heart and the large vessels. The hyperplastic thymus may lead to a grotesque enlargement of the mediastinum on the dv x-ray of the thorax (notice the center drawing in the left and the drawing at the bottom in the right column), or on the lateral x-ray of the thorax to a mass in the anterior mediastinum. A round and an undulating limitation of the mass caused by the ribs or the intercostal spaces are possible indications of a hypertrophic thymus. metu_12b_n.jpg: Sternotomy in an infant. A forceps grasps the depicted structure which is partially covered by connective tissue like a veil. The operative findings in this 6-month-old infant in whom the large thymus persisted beyond the first and second trimenon created therefore the impression of a thymic pathology or a teratoma of the anterior mediastinum. The mass too large for the age of the patient measures at least in the visible part 3-4 to 6-8 cm and exhibits lobular processes (in the picture one of these processes is recognizable on the left side). Owing to the modern x-rays with CT and MRI it is nowadays rarely necessary to perform a diagnostic thoracotomy in the newborn and infant as in the presented case. In addition, a thymic hyperplasia is hardly a possible cause of respiratory signs, such as stridor.