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
Necrotic material undergoing calciﬁcation
The stage is seen in the formation of granuloma
Central necrosis surrounded by lymphocytes
All of the above