Which sinus infection most commonly leads to Periorbital cellulitis?

ANSWER: (A) EthmoidalREF: Khurana page 384, Dhingra 4th Ed Pg 182,190Orbital cellulitis was asked in ENT June 2011The orbital septum is an important landmark in distinguishing between orbital cellulitis (inside the septum) and periorbital cellulitis (outside the septum). Ethmoiditis being the commonest cause of orbital cellulitis.Note: However preseptal/periorbital cellulitis is not commonly caused by sinusitis, the most common sinus involved is Ethmoid sinusPRESEPTAL CELLULITISPreseptal (or periorbital) cellulitis refers to infection of the subcutaneous tissues anterior to the orbital septum. Strictly speaking it is not an orbital disease but is included here under because the facial veins are valveless and preseptal cellulitis may spread posteriorly to produce orbital cellulitis.Causes: Causative organisms are usually staphylococcus aureus, H influenzae or sreptococcus pyogenes.Modes of infection. The organisms may invade the preseptal tissue by any of the following modes.Exogenous infection may result following skin laceration or insect bites.Extension from local infections such as from an acute hordeolum, acute dacryocystitis, ethmoid sinusEndogenous infection may occur by haematogenous spread from remote infection of the middle ear or upper respiratory tract.