What is a Ghon complex, a Ghon focus, and a Ranke complex, and how do these appear on imaging?
A Ghon complex indicates acute TB infection in both the lung and ipsilateral hilar lymph nodes. Acutely, the lymphadenopathy characteristically appears centrally low in attenuation, reflecting necrosis. When the primary site of pulmonary infection heals, a calcified granuloma will often form, termed a Ghon focus. If the affected lymph nodes calcify, the presence of both a pulmonary granuloma and calcified lymph nodes indicates a Ranke complex (