True about Ghon's focus -
Inhaled tubercule bacilli implanted in the distal air spaces of the lower part of upper lobe or upper part of the lower lobe, close to the pleura. This area is about 1 to 1.5 cm with caseating necrosis known as Ghon's focus.
Primary complex or Ghon's complex of tuberculosis consists of 3 components.


Pulmonary compound or Ghon's focus.
Draining lymphatics
Caseating hilar lymph node