Diagnosis issues in sarcoidosis

Multiple problems may be encountered during the diagnosis of sarcoidosis: at first diagnose sarcoidosis in an appropriate clinical setting, secondly, identify any manifestation to be linked to sarcoidosis at diagnosis work-up and during evolution; thirdly, recognize “danger” in sarcoidosis and parasarcoidosis syndromes, and finally, diagnose sarcoidosis recovery. Diagnosis is often delayed as presentation may be diverse, non-specific, or atypical. Diagnosis of sarcoidosis is based on three criteria: a compatible presentation; evidence of non-caseating granulomas and exclusion of any alternative diagnosis. However, even when all criteria are fulfilled, the probability of sarcoidosis diagnosis varies from definite to only possible depending upon the presence of more or less characteristic radio-clinical and histopathological findings and on the epidemiological context. Bilateral hilar lymphadenopathy and/or diffuse lung micronodules mainly along lymphatics are the most frequent highly suggestive findings. Evidence of granulomas relies on superficial biopsies of clinically suspected lesion when present or most often by bronchial endoscopy. The diagnosis of sarcoidosis may be difficult in absence of thoracic or skin manifestations and may require the benefit of hindsight before being definitive. Differential diagnoses, mainly tuberculosis, must be considered. The diagnosis of events during evolution relies on serial clinical, pulmonary function, radiographic evaluation and on extrapulmonary manifestations work-up, including electrocardiogram and blood biology. Affected organs need to be related to sarcoidosis using an appropriate diagnostic assessment instrument. To declare the recovery of sarcoidosis, all manifestations must have disappeared spontaneously or after 3–5 years post-treatment without relapse.