This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
Pott's puffy tumour is related to: 
Select and explain. 
A. Infected cell in middle turbinate, B. Tuberculous sinusitis, C. Pyogenic infection of frontal sinus, D. Cavernous sinus thrombosis
C: Pyogenic infection of frontal sinus
Answer: C: Pyogenic infection of frontal sinus 
Explanation: Pott's puffy tumour is a complication of pyogenic infection of frontal sinus. Pus collects under the periosteum on the anterior surface of the frontal sinus with associated oedema of skin and subcutaneous tissues.