Nasolacrimal Anatomy & Lesions

The nasolacrimal drainage apparatus carries tears from the medial eyelids into the inferior nasal meatus. Imaging should distinguish common obstruction and inflammation from an uncommon but important obstructing neoplasm.A discrete enhancing mass, progressive unilateral symptoms, bone destruction, bloody tearing, or perineural spread should raise concern for malignancy.

Reference Images

Lacrimal drainage anatomy and tear-flow pathway

Canaliculi, lacrimal sac, and nasolacrimal duct — Puncta, canaliculi, lacrimal sac, and nasolacrimal duct

Lacrimal sac obstruction and dacryocystocele

Drainage Anatomy

Upper and lower puncta collect tears at the medial eyelid margins.
Vertical then horizontal canaliculi usually unite as a common canaliculus.
The common canaliculus enters the lacrimal sac; the valve of Rosenmüller limits reflux.
The sac continues as the nasolacrimal duct, approximately 18 mm long and 4.5–5 mm wide.
The duct opens beneath the inferior turbinate at the inferior meatus; the valve of Hasner guards the distal opening.

The sac lies in the lacrimal fossa between the anterior and posterior lacrimal crests.

Normal Imaging & Modality Choice

Modality	Best use	Key assessment
CT	First-line structural survey	Bone remodeling or destruction, calcification/dacryolith, ductal expansion, adjacent sinus disease, and abscess
MRI	Soft-tissue characterization and staging	Enhancement, diffusion, orbital or sinonasal extension, skull-base involvement, and perineural spread
Dacryocystography / CT dacryocystography	Precise obstruction mapping	Level and completeness of stenosis, filling defects, fistula, and postoperative anatomy

A small amount of fluid or air may normally be present in the lacrimal sac or duct. Interpret caliber and contents with symmetry, symptoms, surrounding inflammation, and the presence or absence of an enhancing mass.

Obstruction & Inflammation

Entity	Typical cause / setting	Imaging pattern
Congenital obstruction	Persistent distal membrane at the valve of Hasner	Dilated sac and duct; may form a neonatal dacryocystocele
Primary acquired obstruction	Idiopathic inflammation and fibrosis, typically in adults	Stenosis without a focal mass; chronic sac distention may occur
Secondary acquired obstruction	Trauma, surgery, sinus disease, stones, inflammation, or tumor	Findings depend on cause; scrutinize the full drainage pathway
Acute dacryocystitis	Infected obstructed sac	Enhancing thick-walled distended sac with surrounding preseptal inflammation; abscess may develop
Chronic dacryocystitis	Long-standing obstruction	Sac wall thickening, persistent distention, fibrosis, and recurrent inflammation
Dacryocystocele	Combined proximal and distal outflow obstruction	Cystic medial canthal mass centered on the lacrimal sac, often with ductal dilatation

Complication check: report abscess, orbital extension, adjacent sinus disease, and any intracranial spread.

Obstruction Categories

Congenital: most often distal membranous obstruction.
Primary acquired: idiopathic stenosis from chronic inflammation and fibrosis.
Secondary acquired: infectious, inflammatory, traumatic, iatrogenic, lithiasis-related, or neoplastic.
Functional: impaired lacrimal pump despite an anatomically patent pathway.

Clinical consequences

Epiphora and recurrent discharge
Medial canthal swelling or tenderness
Recurrent dacryocystitis
Rarely, bloody tears or a firm painless mass

Tumors & Mimics

Lesion	Imaging / clinical clues
Squamous cell carcinoma	Most common malignant epithelial tumor; enhancing obstructing mass with possible bone destruction and local invasion
Transitional cell carcinoma	Arises from Schneiderian-type epithelium; may extend along the sac and duct
Lymphoma	Relatively homogeneous soft-tissue mass, often with restricted diffusion and less early bone destruction
Adenocarcinoma / adenoid cystic carcinoma	Infiltrative enhancing mass; adenoid cystic carcinoma warrants careful evaluation for perineural spread
Melanoma	May show intrinsic T1 hyperintensity and susceptibility depending on melanin or hemorrhage
Metastasis or direct invasion	Consider spread from adjacent sinonasal, cutaneous, orbital, or systemic malignancy
Benign mimics	Papilloma, granulomatous disease, inflammatory tissue, dacryolith, foreign body, mucocele, and dacryocystocele

Malignancy Red Flags

Progressive unilateral epiphora
Bloody tears or recurrent unexplained bleeding
Firm, painless medial canthal mass
Mass extending above the medial canthal tendon
Discrete enhancing soft tissue rather than simple fluid distention
Irregular bone erosion or destruction
Orbital, sinonasal, skin, skull-base, or intracranial invasion
Perineural spread or suspicious regional nodes

Reporting Checklist

Epicenter: punctum/canaliculus, lacrimal sac, nasolacrimal duct, orbit, or sinonasal cavity.
Morphology: fluid distention, wall thickening, filling defect, or solid enhancing mass.
Extent: cranio-caudal length and involvement of the sac, duct, inferior meatus, and adjacent soft tissues.
Bone: smooth remodeling, canal widening, pressure erosion, or aggressive destruction.
Inflammation: preseptal/orbital stranding, collection, abscess, or fistula.
Tumor staging: orbital, sinonasal, cutaneous, skull-base, intracranial, and perineural extension.
Nodes and cause: regional adenopathy, sinus disease, dacryolith/foreign body, trauma, or prior surgery.

Practical Impression

State whether the appearance favors simple obstruction, active dacryocystitis, dacryocystocele, or an obstructing mass.

If a mass is present, identify its epicenter and full extent, describe bone response, and recommend contrast-enhanced MRI when soft-tissue or perineural staging is incomplete.

Do not dismiss: unilateral recurrent “dacryocystitis” with a solid enhancing component should be treated as a possible neoplasm until proven otherwise.