Cysts can arise through a variety of processes in the body, including.  1 wear and tear or simple obstructions to the flow of fluid, 2  infections, 3  tumors, 4  chronic inflammatory conditions, 5  genetic (inherited) conditions,  defects in developing organs in the embryo.
1 Acute * sinusitis often develops after a person has had a cold, with symptoms lasting less than 3 weeks. 2  Chronic * sinusitis can last 3 to 8 weeks or longer; it often occurs in people who have allergies or asthma. 3  Recurrent sinusitis consists of several acute episodes of sinusitis in 1 year.
When is Pneumonia Contagious Pneumonia due to fungus, toxins, smoke, and chemicals is not contagious. It is contagious when it is caused by bacteria and viruses. The condition is said to be contagious for 48 hours, or for 2-3 days after starting antibiotics. However, if the antibiotics are taken immediately on the onset of the symptoms, then the contagious period reduces.