Pulmonary and abdominal sarcoidosis, the great imitators on imaging?

Sarcoidosis is an insidious disorder that virtually affects every body organ. Lungs are the site most often affected (in up to 90% of patients) followed by intra thoracic more often than peripheral lymph nodes and other sites can be involved in different percentages. The evaluation of pulmonary sarcoidosis is best performed with high-resolution computed tomography (HRCT), as traditional chest X-ray has a low resolution and can be negative or give non-significant results. Disorders such as interstitial lung diseases (ILDs), tuberculosis, lung cancer and lymphangitis carcinomatosis can manifest with similar radiological findings that can deceive clinics and radiologists. The need of a clear distinction between these conditions is important not only for diagnostic purposes but also because treatment differs significantly in different conditions. However, conventional Ultrasound (US) can be negative if small lesions are present and false negative images can result if US is not followed by a contrast-imaging technique. Contrast enhanced computed tomography (CECT) and magnetic resonance imaging (CEMRI) are preferred to detect single or multiple masses, which appear hypodense and hypointense after contrast agent administration, respectively. We think that a correct algorithm should include a thorough clinical and radiological evaluation, a definite biopsy of affected tissues revealing classical non-caseating granulomas and a certain exclusion of conditions that can give similar clinical/histophatological patterns before considering the diagnosis of sarcoidosis. Only in these cases, a diagnosis of sarcoidosis can be sufficiently achieved before starting an appropriate treatment.