Multimodal Imaging in an Atypical Adult-Onset Lacrimal Sac Mucocele

Abstract

A 61-year-old female presented with a 2-month history of a mass in the right lacrimal sac area after a 10-year persistent epiphora accompanied by occasional ipsilateral discharge. External examination revealed a subcutaneous mass of tough quality, clear boundaries, and poor mobility. Computed tomography showed a low-density oval mass. Axial fat-suppressed T1-weighted magnetic resonance imaging (MRI) showed a slight enhancement around the mass. The special feature of this case was that the slightly high-density oval image on CT, combined with incomplete blockage on dacryography, indicated the tendency of a soft tissue tumor outside the lacrimal sac, whereas the significantly enhanced boundary on MRI was more inclined to a cystic mass. Finally, the mass was excised diagnostically, external dacryocystorhinostomy combined with polyurethane stenting was performed, and histopathology suggested lacrimal sac mucocele. Here, the authors report a rare case of atypical adult-onset lacrimal sac mucocele and emphasize the importance of multimodal imaging evaluation for surgical guidance.

Because of the rarity and low spontaneous resolution rate of 1.6% in adult-onset lacrimal sac mucoceles, atypical tumors are easily misdiagnosed as lacrimal sac tumors.^1,2 Therefore, it is very important to determine whether the lacrimal sac mass is malignant as soon as possible. In the present case, there was no regurgitation of mucopurulent discharge on pressure over the lacrimal sac, and ‌dacryography showed incomplete blockage. In addition, the slightly high-density oval image on computed tomography (CT) indicated the presence of a soft tissue tumor outside the lacrimal sac. However, the significantly enhanced boundary on magnetic resonance imaging (MRI) is more inclined toward a cystic mass. The heterogeneity of the lacrimal sac mass is high, and individualized diagnosis and treatment based on multimodal imaging and pathologic types are necessary.³

CASE REPORT

This case report adhered to the tenets of the 1964 Declaration of Helsinki. Written informed consent was obtained before publication of this paper.

A 61-year-old female was admitted to our hospital with a 2-month history of a mass in the right lacrimal sac area after a 10-year ipsilateral history of persistent epiphora accompanied by occasional discharge. External examination revealed a mild skin bulge and a subcutaneous mass (Fig. 1A, red triangle), ~5×3 mm in size, present below the level of the medial canthal tendon, without regurgitation of mucopurulent discharge on pressure over the lacrimal sac, with tough quality, clear boundary, and poor mobility. The globe position was normal without evidence of proptosis. Slit-lamp and fundus ophthalmic examination results were unremarkable.

FIGURE 1.

Typical images and histopathologic sections: (A)The right lacrimal sac region showing a mild skin bulge (red triangle). (B) Orbital computed tomography (CT) showing a low-density oval mass, ~11×8 mm in size (yellow triangle), with clear boundaries. (C) Orbital MRI (axial fat-suppressed T1-weighted) showing an iso-intensity mass with a slightly enhanced envelope (yellow triangle). (D) Orbital magnetic resonance imaging (MRI) (coronal fat-suppressed T2-weighted) showing a high-intensity part above (red arrowhead) and an iso-intensity part below (yellow arrowhead). (E) Histopathologic section of the mass stained with hematoxylin and eosin (H&E), showing a cyst lined with cuboidal epithelium accompanied by inflammatory cell infiltration.

Diagnostic probing showed a soft stop 8 mm far from the punctum, under pressure irrigation, with partial ingestion and partial regurgitation of mucopurulent discharge, which demonstrated incomplete blockage at the lacrimal sac or nasolacrimal duct. CT showed a low-density oval mass with clear boundaries (Fig. 1B, yellow triangle), which was ~11×8 mm in size, without obvious lacrimal passage imaging, with visible contrast media in the nasal cavity. Further axial fat-suppressed T1-weighted MRI showed a slight enhancement around the mass (Fig. 1C, yellow triangle), which was measured to be ~11×7 mm in size. The coronal fat-suppressed T2-weighted image showed a high-intensity part above (Fig. 1D, red arrowhead) and an iso-intensity part below (Fig. 1D, yellow arrowhead).

The mass was excised diagnostically and external dacryocystorhinostomy (DCR) combined with polyurethane stenting was performed to prevent postoperative epiphora. During the procedure, it was found that the bottom of the mass was located on the surface of the lacrimal sac, between the double-layer epithelium, and that the temporal side was closely connected to the orbital septum. The mass was separated and removed with a size of ~10×8×8 mm, containing a large amount of liquid and yellow-white secretions, and the lacrimal sac was obviously compressed. The final histopathologic section revealed a lacrimal sac mucocele (Fig. 1E). Follow-up observation for half 1 year showed no recurrence of the mass or epiphora.

DISCUSSION

Lacrimal sac mucocele most commonly occurs in infants and children, accounting for ~0.1% of children with the congenital obstruction of both the distal and proximal nasolacrimal duct, typically presenting as a bulging in the lower medial canthus of the ipsilateral eye, after a history of prior epiphora.⁴ Among the children with lacrimal sac mucoceles, 91% had unilateral onset and 23% required surgical intervention.⁵ Although relatively rare, adult-onset lacrimal sac mucoceles may be secondary to nasolacrimal duct obstruction caused by recurrent chronic dacryocystitis or trauma.⁴ However, the case we reported had no prior history of chronic dacryocystitis and no regurgitation of mucopurulent discharge on pressure over the lacrimal sac. The main imaging features were the incomplete blockage on dacryography and a slightly high-density oval image on CT. Therefore, we initially considered that the patient’s clinical manifestations were caused by the compression of a soft tissue tumor outside the lacrimal sac.

Considering the complexity, diversity, and high-grade malignancy of tumors (including lymphoma, malignant melanoma, embryonal rhabdomyosarcoma, and squamous cell carcinoma et al) in the lacrimal sac area, multimodal imaging is necessary.^3,6 Paradoxically, further axial fat-suppressed T1-weighted MRI revealed a suspected cyst with an enhanced envelope, and coronal fat-suppressed T2-weighted MRI showed a high-intensity part above and an iso-intensity part below. The combination of CT and MRI enriched the imaging information of this case and further increased its atypicity. As previously reported, malignant tumors often occurre in 50 to 60-year-old people, characterized by insidious onset and lack of specific clinical manifestations, without difference in sex and race.⁵ To further diagnose and treat the case, the patient underwent mass resection and external DCR combined with polyurethane stenting, with the final histopathologic section suggesting a diagnosis of lacrimal sac mucocele.

Tumors in the lacrimal sac area can be primary benign and malignant tumors of the lacrimal sac, secondary lesions in the orbit, conjunctiva and other tissues, and may also be local manifestations of systemic disease. Therefore, multimodal imaging evaluations have very important implications for diagnosis and surgical treatment.³ In our case, CT showed that the right lacrimal sac region and nasolacrimal duct were compressed and narrow, and no bone damage was observed in the lacrimal sac and nasolacrimal duct. On the basis of CT alone, it was easily misdiagnosed as a mass outside the lacrimal sac, with great difficulty in distinguishing the benign from malignant nature. However, MRI did not show significant enhancement of the suspected cyst, and a benign cystic lesion of the lacrimal sac was considered. In conclusion, a combination of CT and MRI provided accurate preoperative guidance.

Because of the severe compression of the lacrimal sac seen during intraoperative exploration, a double-flap external DCR under direct vision was performed to prevent postoperative epiphora. At the 6-month follow-up, no mass or epiphora recurrence was observed, which was consistent with literature reports that the external DCR had an extremely high success rate (no recurrence of tears at the postoperative 6-mo follow-up) of 76.2%.⁷ According to several literature reports,^7,8 the major reason for surgical failure was intranasal ostial closure, due to granulation or scar tissue. Therefore, we combined polyurethane stenting with external DCR to ensure long-term success.