Head and Neck ImagingNasolacrimal canal, pathology
- distal
obstruction (at the level of valve of Hasner) due to persisting membrane: most common
congenital anomaly of the nasolacrimal duct, spontaneously resolving in most cases during the first year of life. In most cases, persisting
obstruction can be treated effectively by probing. A
congenital dacryocystocoele occurs when the nasolacrimal drainage system has concomitant blocks at the level of the junction of the common canaliculus with the lacrimal sac and at the distal end of the nasolacrimal canal; spontaneous
resolution is common, but dacryocystitis may supervene (
Fig. 1).
- rarely, a fistula may be present between the
lacrimal sac
and the overlying skin (usually medial and inferior to the medial canthus).
Primary acquired nasolacrimal duct
obstruction or
obstruction of the lacrimal drainage system by progressive atrophy, mainly affecting the lacrimal sac and nasolacrimal duct, without specific cause. Asymptomatic
obstruction of the lacrimal drainage system is seen in over 35% of people aged 90 and older.
Long-term
stenosis may lead to formation of diverticula on the nasolacrimal canal (
Fig. 2).
Dacryocystitis
Acute dacryocystitis is an infection of the lacrimal sac, presenting as a red, painful swelling. Preexisting
obstruction of the nasolacrimal drainage system is a risk factor. Incision of the lacrimal sac may be necessary to evacuate the abscess.
Obstruction of the lacrimal drainage system may result in chronic dacryocystitis. Chronic dacryocystitis may become complicated by fistula formation.
Dacryolith
Stone within the nasolacrimal system, originating de novo or by precipitation of calcium and phosphate salts on foreign material. Such a stone may cause
intermittent epiphora without
inflammation; patients with dacroliths may also present with recurrent dacryocystitis. A dacroylith becomes visible as a filling defect on
dacryocystography
.
Fractures through the bony nasolacrimal canal may cause
obstruction. Iatrogenic damage to the nasolacrimal canal may occur during surgical procedures such as the
Caldwell-Luc procedure
or rhinoplasty.
Tumors
Neoplastic disease of the nasolacrimal canal is very rare. Most malignancies occuring in the lacrimal system are
squamous cell carcinoma, head and neck
, but also
lymphoma
may occur. Extension of a
malignant tumor from a neighbouring structure may cause secondary
obstruction of the lacrimal system.
Benign lacrimal canal tumors, such as papilloma or polyp, have been described.
RH