Ghon focus
A Ghon focus is a primary lesion usually subpleural, often in the mid to lower zones, caused by mycobacterium bacilli (tuberculosis) developed in the lung of a nonimmune host (usually a child). It is named for Anton Ghon (1866–1936), an Austrian pathologist.
It is a small area of granulomatous inflammation, only detectable by chest X-ray if it calcifies or grows substantially (see tuberculosis radiology).[1] Typically these will heal, but in some cases, especially in immunosuppressed patients, it will progress to miliary tuberculosis (so named due to the granulomas resembling millet seeds on a chest X-ray).[1]
The classical location for primary infection is surrounding the lobar fissures, either in the upper part of the lower lobe or lower part of the upper lobe.[1]
If the Ghon focus also involves infection of adjacent lymphatics and hilar lymph nodes, it is known as the Ghon's complex or primary complex. When a Ghon's complex undergoes fibrosis and calcification it is called a Ranke complex.[1][2]
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