A 6 month old baby ill with bronchitis was taken for an X-ray of chest. Apart of changes associated with bronchi the X-ray film showed a shadow of thymus gland. What might have caused such changes?

Answer options

1. It is caused by abnormal position
2. It’s the effect of bronchitis
3. The above-mentioned condition is a normal variant for this age
4. It is caused by neoplastic process
5. It is caused by thymus inflammation

Explanation

There is a certain correlation between the age of an individual and thymus activity. In neonates, it already appears to have a considerable mass of 13.3g on average. Most intensive growth occurs during the first 3 years of life when the gland doubles in size. Having reached the maximum weight (about 26-30g), the thymus retains it until 20 years of life. After 20 years of age, the thymus parenchyma experiences gradual involution and is substituted with fat tissue. After 50 years of age, the fat constitutes 90% of the land mass. It is therefore normal to see a shadow of the thymus gland in a 6-month-old child.