An infant is brought to you with chief c/o irritability, lethargy, and decreased oral intake. Examination reveals postauricular redness, swelling and proptosis. His temp is 37.9oC. He has a sibling with a history of recurrent AOM.
What is the most likely diagnosis at presentation?
A. Basilar skull fracture
B. Acute parotitis
C. Acute mastoiditis
D. Branchial cleft cyst