Pseudodacryocystitis refers to anterior ethmoidal sinus inflammation, usually with superimposed infection, extending into the adjacent lacrimal sac region and consequently giving a clinical presentation similar to dacryocystitis.
Unlike dacryocystitis, clinical irrigation typically shows patency of the lacrimal system's drainage. On imaging, sinusitis is demonstrated in the adjacent anterior ethmoidal air cell, with associated bone erosion into the region of the lacrimal sac.
The treatment of both entities differs if antibiotic therapy fails: in pseudodacryocystitis, an anterior ethmoidectomy is the preferred therapy, as opposed to dacryocystorhinostomy in those with dacryocystitis.