Differential Diagnosis

The differential diagnosis of a lacrimal sac mass is shown in Table 20.1. The other major cause of an apparent lacrimal sac mass is chronic or acute dacryocystitis. Dacryocystitis typically has an acute onset associated with pain and erythema of the overlying soft tissues, with the epicenter of inflammation located inferior to the medial canthal tendon. Purulent discharge or even a cutaneous fistula may be present.

Additional causes of swelling in the region above the medial canthal tendon include meningocele and encephalocele, although these entities present more commonly in children than in adults (Chapter 28). Dermoids, ethmoidal mucoceles, granulomas, and paranasal sinus cancers extending into the lacrimal sac area are other causes of a palpable lacrimal sac lesion.

Investigations

A careful physical examination should include palpation of the mass and observing for egress of any material from the punctum with direct pressure over the lacrimal sac. The material may be clear, mucinous, purulent, or sanguinous. The preauricular, parotid, and cervical lymph nodes should be palpated to detect lymphadenopathy. The LOS is evaluated with probing and irrigation if tolerated by the patient. Nasal endoscopy should rule out obvious intranasal mass lesions.

If an LOS malignancy is suspected, high-resolution computed tomography (CT) or magnetic resonance imaging (MRI) of the head and neck region are organized.

Controversy: Although the role of routine imaging for patients with “routine” dacryostenosis is uncertain,^47–50 the utility of imaging in patients with an obvious mass is well accepted.

CT provides more detail than MRI about the bony anatomy of the nasolacrimal duct, whereas MRI provides more detail than CT about the soft tissue anatomy in the medial canthal region. Because CT is quicker, less expensive, and more available than MRI, it is usually ordered first for suspected LOS malignancies (Fig. 20.2). Helical CT scanning and three-dimensional reconstruction techniques provide high-resolution images, particularly when these techniques are combined with injection of contrast material directly into the lacrimal outflow system.⁵¹ This digitally subtracted CT-dacryocystogram (DCG) provides the greatest detail of neoplasms and foreign bodies within the LOC. Traditional DCG (radiography rather than CT) may provide information about dacryoliths and large intraluminal neoplasia but is less sensitive in identifying extrinsic masses and small intraluminal masses.

Controversy: The ease of obtaining CT scans has prompted some authors to advocate routine preoperative CT scans for dacryostenosis.⁴⁹ However, the yield of routine CT before DCR is unclear. One such study identified two of 107 patients with an extrinsic process causing obstruction: one patient had an inverted papilloma, and one had lymphoma, both tumors arising from the sinuses. No patients had an intrinsic nasolacrimal duct lesion causing obstruction.⁴⁹ Despite the nearly 2% yield in this study, few surgeons advocate routine CT scanning before DCR. Many do obtain a CT in the presence of bloody tears, evidence of a mass, history or malignancy, or other suspicious features.

Although there have been reports of the use of ultrasonography for examining lesions of the lacrimal sac,^52,53 this has not gained widespread popularity because of the availability and increased sensitivity of CT and MRI.

To confirm the diagnosis of a LOS malignancy, biopsy and histopathologic evaluation of the biopsy specimen are necessary.

Controversy: It remains uncertain whether to send lacrimal sac tissue for pathologic review during a routine DCR in which no obvious abnormality is appreciated. Malignancies may be found on lacrimal sac biopsy during routine DCR when no abnormality is suspected. One series found neoplasia in 17% of patients undergoing DCR when no disease was suspected, but the incidence of malignant lesions was not reported.⁴⁸ Anderson et al. reported that only 2.1% of DCR specimens demonstrated an unsuspected neoplasm.²¹ Interestingly, some clinicians feel that this 2% to 17% range argues against routine biopsy of the sac during DCR,⁴⁷ whereas others interpret the same facts in support of routine biopsy.

Pathology

Ryan and Font classified epithelial lesions of the lacrimal sac on the basis of the growth pattern as exophytic, inverted, or mixed papillomatous lesions and further subdivided epithelial lesions as squamous, transitional cell, or mixed.⁵ Exophytic lesions show the classically described fingerlike fronds of outward epithelial proliferation into the lumen of the lacrimal sac. Inverted lesions demonstrate growth toward the stroma of the lacrimal sac and nasolacrimal duct but with an intact, thickened basement membrane unless invasive carcinoma is seen. Squamous papillomas demonstrate an acanthotic, stratified squamous epithelium with a variable amount of plasma cell and lymphocytic infiltrate (Fig. 20.3), whereas transitional cell papillomas demonstrate a more stratified columnar epithelium and may also contain inflammatory cells and goblet cells.¹⁸

Squamous and transitional cell carcinomas demonstrate more atypia compared with their benign counterparts. Signs of carcinoma include various degrees of keratin formation (keratin pearls), intercellular bridging, increased eosinophilic cytoplasm, pleomorphic nuclei with prominent nucleoli, and increased numbers of mitotic figures (Fig. 20.4).¹⁸

Other epithelial lesions such as oncocytomas, oncocytic adenocarcinomas, and mucoepidermoid carcinomas do not fit as cleanly into such a classification scheme.

Immunohistochemical staining can help determine tumor type and tissue of origin in LOS neoplasms. Of particular importance are three cytokeratin markers (34 beta E12, CAM 5.2, and cytokeratin 7) and a marker for epithelial membrane antigen, which is expressed on certain glandular and ductal cells. In addition, CK20 can be used to identify carcinomas arising from various anatomic sites.²⁷ This small panel of markers can help distinguish whether a lacrimal sac lesion is primary, secondary, or metastatic in origin.

LOS lymphomas are histologically similar to lymphomas found elsewhere. A dense lymphocytic infiltrate can be seen with varying degrees of follicular differentiation (Fig. 20.5). Studies that are routinely obtained for lymphomas in other parts of the body, such as flow cytometry, immunohistochemistry, and molecular studies, are also obtained for lymphoid lesions involving the LOS to classify the type of lymphoma and to rule out a more benign polyclonal lymphocytic infiltrate or inflammation.²¹

Melanocytes from LOS melanomas are easily visualized with immunohistochemical stains using the melanoma markers HMB45 and Melan A. Cells are typically large and polyhedral with dark-stained nuclei and pigment-containing granules (Fig. 20.6).