Sarcoidosis exclusion criteria: the “simple truth” for a “complicated diagnosis”

The differentiation between sarcoidosis and sarcoid-type reactions remains a clinical and histopathologic diagnostic dilemma. A definitive distinction is yet to be determined according to the current literature data. Sarcoid-like tissue reactions with identifiable infectious or other immunogenic antigens, should be classified as non-specific clinical manifestations of a specific disease. The current assignment of this type of reaction under the generic umbrella of “sarcoidosis” is incorrect and may result in the subsequent misinterpretation of the definition of the disease in general. On the other hand, this may lead to clinical studies with incorrectly selected inclusion criteria and, therefore, contradictory statements regarding the epidemiology and pathogenesis of the disease. Thus we propose the introduction of new criteria for exclusion of sarcoidosis as an autonomous disease. Recent trials on patients with probable sarcoidosis have focused on ideal criteria, or have provided information about the genetic and immunological profile of patients with specific infections or other diseases, which manifest themself as sarcoidal granulomas. This could explain the heterogeneous clinical and/or genetic profiles of the reported patients, who in fact were not affected by the autonomous disease “sarcoidosis”. The simplification of the current available data regarding this issue will be of fundamental importance for the correct direction of future studies, whose aim is to unravel the pathogenesis of the immunological cascade in patients with sarcoidosis and sarcoid-like type of reaction. It is expected that the introduction of exclusion criteria will inevitably lead to a change in the approach to diagnosis as well as the fundamental understanding of this mysterious disease, known as sarcoidosis.