The lacrimal gland is a bilobed eccrine secretory gland, which is situated in the superotemporal orbit. The 2 lobes of the lacrimal gland, the orbital lobe and the much smaller palpebral lobe, are separated anatomically by the lateral horn of the levator aponeurosis. Only the palpebral lobe can be visualized in the superior fornix on lid eversion. Thus, disease processes that solely affect the orbital lobe may not manifest until later in the course of the illness.
Mass lesions of the lacrimal gland can be classified broadly into inflammatory and neoplastic subtypes. Inflammatory etiologies, while not uncommon, include dacryoadenitis, sarcoidosis, and orbital inflammatory pseudotumor. For the purposes of this discussion, the focus will be on neoplastic lesions of the lacrimal gland. Most of the neoplastic lesions in the lacrimal gland are epithelial in origin, with approximately 50% classified as benign and 50% as malignant.
Benign lesions include pleomorphic adenomas (benign mixed cell tumors), benign reactive lymphoid hyperplasia, and oncocytomas. These lesions are slowly growing masses more commonly found in adults in their forth to fifth decades of life. Malignant tumors of the lacrimal gland include adenoid cystic carcinoma, adenocarcinoma, squamous cell carcinoma, mucoepidermoid carcinoma, and malignant lymphomas.
Adenoid cystic carcinoma is the most common malignant lacrimal gland tumor, comprising 50% of malignant tumors of lacrimal gland and 25% of all lacrimal gland tumors. Most cases are seen in the third decade of life with a second bimodal peak in the teenage years.
Data about the prevalence of lacrimal gland tumors is quite sparse in the literature as this condition is quite rare. Malignant epithelial neoplasms of the lacrimal gland account for approximately 2% of all orbital neoplasms. Similarly, epithelial neoplasms account for only 4% of all lacrimal gland lesions.
Patients with lacrimal gland tumors, especially malignant ones, need to be observed long term before successful treatment can be claimed. The approximate 15-year mortality rate approaches 75%.
Lacrimal gland tumors are seen more frequently in the third decade of life, and the second bimodal peak is in the teenage years.