Diagnostic utility of bony nasolacrimal duct area on computed tomography for differentiating malignant lacrimal tumors.

PURPOSE: To determine whether the expansion ratio of the bony nasolacrimal duct on computed tomography (CT) can differentiate malignant lacrimal tumors from benign lesions and primary acquired nasolacrimal duct obstruction (PANDO).

METHODS

The study retrospectively analyzed 19 patients with malignant lacrimal tumors and 195 with unilateral PANDO who visited the Kyushu University Hospital and underwent CT-dacryocystography between April 2018 and March 2023. Of the 195 PANDO cases, 14 that developed a lacrimal sac mass associated with chronic dacryocystitis were defined as the benign mass group. Clinical data including age, sex, tumor location and histopathology, and CT findings of the bony nasolacrimal duct were obtained via medical records.

RESULTS

The malignant tumor group included 12 males and 7 females, and the mean age was 54.7 years. The benign mass group included 7 males and 7 females, and the mean age was 67.5 years. The PANDO group included 39 males and 142 females, and the mean age was 70.3 years. Tumor locations in patients with malignant tumors, including overlapping sites, were the lacrimal sac in 17 cases, the nasolacrimal duct in 9, the canaliculus in 2, and the nasal cavity in 1. Histopathological diagnoses were squamous cell carcinoma in 8 cases, malignant lymphoma in 4, adenoid cystic carcinoma in 2, and 1 case each of sebaceous carcinoma, mucoepidermoid carcinoma, apocrine adenocarcinoma, rhabdomyosarcoma, and Langerhans cell histiocytosis. Tumor locations in patients with benign masses were the lacrimal sac in 11 cases, the nasolacrimal duct in 2, and the nasal cavity in 1. Histopathological diagnoses were inflammatory granulation tissue in 11 cases and cyst in 3. Median expansion ratios of the bony nasolacrimal duct (affected side/unaffected side) on axial CT were 167.5% in the malignant tumor group, 123.3% in the benign mass group, and 106.8% in the PANDO group.

CONCLUSION

Malignant lacrimal tumors showed considerably greater expansion of the bony nasolacrimal duct on CT. An expansion ratio of ≥ 150% may be a useful adjunctive marker for distinguishing malignant lacrimal tumors in clinical practice.