Sarcoidosis, which is characterized by collections of noncaseating granuloma, can affect any organ, most commonly the lungs. It may also affect the orbit. In America, the disease occurs 3 to 4 times as frequently in individuals of African descent as in those of European or Asian descent.
Within the orbit, the disease most frequently affects lacrimal gland, typically bilaterally. Gallium scanning, although nonspecific, shows lacrimal gland involvement in 80% of patients with systemic sarcoidosis, although only 7% of patients demonstrate clinically detectable lacrimal gland enlargement. Subconjunctival nodules (Fig 4-15A, B) and other orbital soft tissues, including the extraocular muscles and optic nerve, are involved only in rare cases. Infrequently, there is sinus involvement, with associated lytic bone lesions invading into the adjacent orbit. The disease may also affect the nasolacrimal drainage system, producing nasolacrimal duct obstruction.
Figure 4-15 Sarcoidosis. A, Sarcoidosis presenting in a patient as left subconjunctival nodules. B, Orbital coronal CT scan shows the lesion in the anterior orbit. C and D, CT scans of the chest show bilateral hilar adenopathy.
(Courtesy of Bobby S. Korn, MD, PhD.)
Chest radiography, CT, or gallium scans may detect hilar adenopathy or pulmonary infiltrates (Fig 4-15C, D). Serologic testing may show elevated levels of angiotensinconverting enzyme (ACE), lysozyme, and calcium. ACE is produced by the epithelioid cells and macrophages found in sarcoid granulomas, so the ACE level reflects the mass of granulomas in the body and the severity of sarcoidosis.
Regardless of serologic and imaging findings, when possible, it may be best to confirm the diagnosis with tissue biopsy. Biopsy of an affected lacrimal gland or of a suspicious conjunctival lesion may establish the diagnosis; however, random conjunctival biopsies have a low yield. Bronchoscopy with bronchial washing and biopsy may confirm pulmonary involvement. Histologic examination reveals noncaseating collections of epithelioid histiocytes in a granulomatous pattern, with mononuclear cells often appearing at the periphery of the granuloma.
Isolated orbital lesions can occur without associated systemic disease; this condition is called orbital sarcoidosis. Interestingly, patients with either isolated or systemic sarcoidosis involving the orbit rarely develop intraocular involvement and vice versa.
See BCSC Section 5, Neuro-Ophthalmology, and Section 9, Uveitis and Ocular Inflammation, for more extensive discussion and clinical photographs of sarcoidosis.
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.