<prompt> What is Ranne complex?Necrotic material undergoing calcificationThe stage is seen in the formation of granulomaCentral necrosis surrounded by lymphocytesAll of the above  <response>: 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: Shafers textbook of oral pathology 7th edition page 320 