Imaging is helpful in evaluating lesions in the lacrimal gland region. Inflammatory and lymphoid proliferations in the lacrimal gland tend to cause it to expand diffusely and appear elongated, whereas epithelial neoplasms tend to appear as isolated globular masses. Inflammatory and lymphoproliferative lesions usually mold around the globe, but epithelial neoplasms tend to displace and indent it. The bone of the lacrimal fossa is remodeled in response to a slowly growing benign epithelial lesion of the lacrimal gland; however, lymphoproliferative lesions typically do not cause bony changes.
Epithelial Tumors of the Lacrimal Gland
Approximately 50% of epithelial tumors are benign mixed tumors (pleomorphic adenomas), and about 50% are carcinomas. Approximately half of the carcinomas are adenoid cystic carcinomas, and the remainder are malignant mixed tumors, primary adenocarcinomas, mucoepidermoid carcinomas, or squamous carcinomas.
Pleomorphic adenoma is the most common epithelial tumor of the lacrimal gland. This tumor usually occurs in adults during the fourth or fifth decade of life and affects slightly more men than women. Patients present with a progressive, painless inferior and medial displacement of the globe with axial proptosis (Fig 5-21A). Symptoms usually persist for more than 12 months.
A firm, lobular mass may be palpated near the superolateral orbital rim, and orbital imaging often reveals enlargement or expansion of the fossa of the lacrimal gland. On imaging, the lesion appears well circumscribed but may have a slightly nodular configuration (Fig 5-21B, C).
Microscopically, pleomorphic adenomas have a varied cellular structure consisting primarily of a proliferation of benign epithelial cells and a stroma composed of spindle-shaped cells with occasional cartilaginous, mucinous, or even osteoid degeneration or metaplasia. Because of this variability, the term benign mixed tumor is sometimes used. The lesion is circumscribed by a pseudocapsule.
Figure 5-21 Pleomorphic adenoma. A, Adult male with inferomedial displacement of the right globe. B, Axial CT scan shows a well-circumscribed mass in the superotemporal orbit with no lytic erosion of the bone. C, Coronal CT shows the mass displacing the right globe inferiorly and medially. D, The mass was completely removed with the pseudocapsule intact through a lateral orbitotomy approach.
(Courtesy of Eric A. Steele, MD.)
Treatment is complete removal of the pleomorphic adenoma with its pseudocapsule and a surrounding margin of orbital tissue (Fig 5-21D). Surgery should be performed without a preliminary biopsy: in an early study, the recurrence rate was 32% when the capsule was incised for direct biopsy. In recurrences, the risk of malignant degeneration into carcinoma ex pleomorphic adenoma is 10% per decade.
Chawla B, Kashyap S, Sen S, et al. Clinicopathologic review of epithelial tumors of the lacrimal gland. Ophthalmic Plast Reconstr Surg. 2013;29(6):440–445.
Adenoid cystic carcinoma
Adenoid cystic carcinoma (ACC) is the most common malignant epithelial tumor of the lacrimal gland. This highly malignant carcinoma may cause pain because of perineural invasion and bone destruction. The relatively rapid course, with a history of generally less than 1 year, and early onset of pain help differentiate ACC from pleomorphic adenoma, which is painless and characteristically exhibits progressive proptosis for more than a year. The tumor usually extends into the posterior orbit because of its capacity to infiltrate and its lack of true encapsulation.
Microscopically, this tumor is composed of deceptively benign-appearing cells that grow in tubules, solid nests, or a Swiss-cheese pattern. The basaloid morphology is associated with worse survival than the cribriform variant. Infiltration of the orbital tissues, including perineural invasion, is often seen in microscopic sections.
Malignant mixed tumor
These lesions are histologically similar to pleomorphic adenomas (benign mixed tumors), but they have areas of malignant change, usually poorly differentiated adenocarcinomas. They typically arise from a long-standing primary pleomorphic adenoma or from a pleomorphic adenoma that has recurred after initial incomplete excision or violation of the pseudocapsule (see the section “Pleomorphic adenoma”). An increase in growth rate is a hallmark of malignant degeneration.
Management of malignant lacrimal gland tumors
Suspicion of a malignant lacrimal gland tumor warrants biopsy with permanent histologic confirmation. Traditional treatment is centered around orbital exenteration or radical orbitectomy followed by radiotherapy; however, the survival benefit of exenteration remains unproven. Other treatment strategies include neoadjuvant intra-arterial chemotherapy followed by exenteration or eye-sparing surgery followed by radiation (typically proton) therapy. Despite these measures, ascending perineural extension often develops, usually leading to death from intracranial extension or, less commonly, from systemic metastases (managed by local resection) a decade or more after the initial presentation.
Tse DT, Kossler AL, Feuer WJ, Benedetto PW. Long-term outcomes of neoadjuvant intra-arterial cytoreductive chemotherapy for lacrimal gland adenoid cystic carcinoma. Ophthalmology. 2013;120(7):1313–1323.
Woo KI, Kim YD, Sa HS, Esmaeli B. Current treatment of lacrimal gland carcinoma. Curr Opin Ophthalmol. 2016;26(5):449–456.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.