Overlap syndromes in sarcoidosis: Unveiling the masquerader

As a multi system granulomatous disease, clinical presentations of sarcoidosis are highly variable. In the absence of a stereotypical clinical presentation such as asymptomatic bilateral hilar adenopathy, Lofgren's syndrome, or lupus pernio, a diagnosis of sarcoidosis typically requires 1) compatible clinical presentation, 2) histologic evidence of granulomatous inflammation, and 3) the exclusion of other causes. The clinical presentation of sarcoidosis is often nonspecific and a variety of other causes of granulomatous inflammation can make diagnosing sarcoidosis a challenge for clinicians. "Overlap syndromes" are often used to describe clinical presentations of sarcoidosis that share histologic and clinical features of other diseases, or when the diagnosis of sarcoidosis is made in association with the coexistence of another diagnosis with similar clinical or histologic findings. Because of the risk of diagnostic delay and diagnostic errors, it is vital for clinicians to be familiar with overlap syndromes in sarcoidosis. The coexistence of sarcoidosis with other diseases can also significantly impact disease management and outcomes. This article will review the most current published data on overlap syndromes in sarcoidosis to aid clinicians in diagnosing and managing these complex patients.