Masquerade Syndromes

The masquerade syndromes comprise a group of disorders that mimic an ocular inflammatory disease requiring anti-inflammatory therapy. These disorders are often misdiagnosed as chronic idiopathic uveitis. The term masquerade syndrome was first used in the ophthalmic literature in 1967 to describe conjunctival carcinoma manifesting as a case of chronic conjunctivitis ; today, however, it is used most commonly to describe disorders simulating chronic uveitis. Because many of the masquerade syndromes are malignant processes, early diagnosis and prompt treatment are critical ( Box 31.1 ). Other disorders, such as retinal degenerations and intraocular foreign body, can also masquerade as uveitis, and, again, misdiagnosis frequently leads to inappropriate therapy. There is a semantic debate on whether certain infectious conditions, such as Propionibacterium acnes endophthalmitis or herpes simplex virus–associated uveitis, should be considered a masquerade syndrome. Some experts exclude any ocular infections from the masquerade syndromes, but I prefer to include them when they are not easily recognized as infectious diseases, especially because these ocular infections can mimic idiopathic uveitis and cause adverse sequelae when treated with anti-inflammatory therapy alone. I prefer to limit the diagnosis of masquerade syndromes to malignancies and conditions where an underlying inflammatory disease or infection is not the main cause of the pathology and where anti-inflammatory therapy alone may be inappropriate to optimize patient outcomes. Examples include infections, where antimicrobial therapy is warranted; malignancy, where cancer treatment is required; adverse reactions to medications, where the offending therapy should be stopped; or trauma, where an intraocular foreign body should be removed. There are also conditions that mimic intraocular inflammation where no therapy is needed, such as asteroid hyalosis. The focus of this chapter is on the malignant conditions that can masquerade as uveitis, but nonmalignant disorders often misdiagnosed as chronic idiopathic ocular inflammatory disease are also discussed.