Imaging techniques in the diagnosis of lacrimal sac diverticulum.

Lacrimal sac diverticulum is a rare condition characterized by a cystic structure communicating with the sac. This abnormality may be directly demonstrated by dacryocystography only in a few cases; in the remaining cases, preoperative diagnosis may be arduous. We report 3 cases of lacrimal sac diverticulum. In all patients, symptoms were represented by a palpable mass in the lacrimal sac region, associated with permanent (case 1) or episodic (cases 2 and 3) epiphora. In the first case, CT-dacryocystography revealed an apparently solid mass causing inferior lacrimal obstruction, and ultrasonography disclosed a cystic space, not communicating with the sac. At surgery, a sac diverticulum was identified and excised. In the second patient, CT showed a homogeneous rounded mass, whereas a cystic character was revealed by T1-weighted MRI. Dacryocystography showed a lateral impression on the lateral wall of the sac. Ultrasonography revealed a cystic space communicating with the lacrimal sac. In the third case, ultrasonography demonstrated a diverticulum. CT is often unable to discriminate tumors from lacrimal cysts, both showing a parenchymal density. MRI can differentiate lacrimal cystic spaces from solid tumors by T1 intensity and by demonstration of their walls, but it is nonspecific for diverticula. Only dacryocystography and B-scan ultrasonography can reveal the narrow communication between the sac and the diverticulum. Observation is the recommended management for asymptomatic cases.