What is Ranne complex?

The central part of the TB lesion contains caseous, soft, and cheesy necrotic material (caseous necrosis). This necrotic material may undergo calcification at a later stage called Ranne complex, in the lung parenchyma and hilar lymph nodes in few cases. Key concept: Necrotic material undergoing calcification which is seen in TB is known as Ranne complex. Ref: Shafer's textbook of oral pathology 7th edition page 320