Let me first reassure you that it is really common, especially in the winter, for a 9-month-old to be diagnosed with bronchiolitis, an infection of the linings of the small airways in the lungs that can be mild or severe. In fact, it is the most common reason for an infant to be hospitalized each year.

Your infant son probably had what seemed like just a normal cold, but then after a few days or so, I'll bet he started to show signs of breathing difficulty and getting worse instead of better. He may have seemed irritable, looked anxious and uncomfortable, and had a hard time eating or drinking as much as usual.

He may have been breathing much faster than usual (tachypnea), wheezing, having a "tight" or harsh-sounding cough, or even a bluish discoloration to his lips or skin (cyanosis). His nostrils may have flared out or his chest muscles pulled in (retracted) to get as much air in as possible. I hope he is feeling better after this well known illness.

On the other hand, I'm not sure what to make of your son's chest X-ray finding of "calcium deposits." Lots of infants have bronchiolitis and most don’t end up even needing a chest X-ray; of those who do, we are usually looking for something else, such as pneumonia. Having calcium build up in the lungs due to bronchiolitis is news to me.

Some things known to cause lung calcification include infections (for example, histoplasmosis or tuberculosis); endocrine gland problems when the body has problems handling the calcium we have and need; and rare conditions like sarcoidosis or amyloidosis. These are all rare in babies.

Without knowing your son's medical history, it is impossible to say for certain that the calcifications are related to the bronchiolitis. Maybe these calcifications have been present since birth, but just were never detected because your son has been so healthy. Either way, since this finding is so unusual, I'd discuss your concerns with his doctor.