Histopathology is valuable in confirming the diagnosis whenever possible, and common sites include lung, lymph node, skin, liver, and bone marrow. Pathology reveals granulomatous inflammation (usually noncaseating). In 3 situations, however, a diagnosis can be reasonably established without biopsy: Löfgren syndrome (erythema nodosum, hilar adenopathy, migratory polyarthralgia, and fever), Heerfordt-Waldenström syndrome (parotid gland swelling, facial nerve palsy, uveitis, and fever), and asymptomatic bilateral hilar adenopathy. Biopsy of erythema nodosum skin lesions is not helpful, as granulomas are not associated with the eruption.
No serologic test is pathognomonic for sarcoidosis. Although serum angiotensin-converting enzyme (ACE) is elevated in 75% of patients, poor sensitivity and reduced specificity limit its usefulness. Pulmonary imaging is helpful and may include radiography, computed tomography, or positron-emission tomography scans. An ophthalmologic exam is important as part of the workup of any patient suspected of having sarcoidosis.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.