This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
All of the following are diagnostic criteria of allergic fungal sinusitis {AFS} Except ? 
Select and explain. 
A. Areas of high attuenuation on CT scan, B. Orbital invasion, C. Allergic eosinophilic mucin, D. Type 1 Hypersensitivity
B: Orbital invasion
Answer: B: Orbital invasion 
Explanation: CT scan shows mucosal thickening with hyperdense areas in fungal sinusitis. Allergic fungal sinusitis is due to the type 1 hypersensitivity reaction to fungal hyphae. It presents with sinonasal polyposis and mucin. (Ref: Textbook of ENT, Diseases of ENT, Dhingra, 7th edition, pg no. 220)