Primary  Tubercle  (Ghon Tubercle):

When  an  individual with  no  previous exposure  to  tuberclosis inhale a sufficient number of  tubercle bacilli into the alveoli, tuberculosis infection occurs. Inflammation occurs within the parenchyma of  the  lungs. Body  counteracts  the infection with  the natural  body defenses. Lymph  nodes in  the  hilar region  of the  lung become  enlarged as  they  filter drainage  form  the  infected site. The inflammatroy process and cellular reaction produce a small, firm white  nodule called  the  primary tubercle.

Calcifid Nodule  or Chon Tubercle:

The center of the primary tubercles contains tubercle bacilli. Cells gather around the center, and usually the outer portion becomes fibrosed. As blood vessels get compressed interfering with nutrition of  the tubercle, necrosis occurs at the center.

The area becomes walled off by fibrotic tissue around the outside, and the center gradually becomes soft and cheesy in consistency. This process is known as caseation necrosis. This material may become calcified (Ghon tubercle). Most people who are exposed  to tuberculosis and develop infection do not have active tuberculosis. X-ray shows the calcified nodule. The hilar lymph nodes and a Ghon tubercle seen is X-ray is referred as the primary complex. Person who have primary complex will show positive result inobatin  test. However a nurse needs to explain to the clients that a positive tuberculin test does not mean that helshe has tuberculosis. Body's reaction to  the organism. A person who has been unless with tubercle bacilli harbours the organism for the remainder of he person's  life unless he or she has received prophylactic isonizid. When a person is under physical or emotional stress, the bacilli lying dormant in the lungs become active.