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Introduction: Sarcoidosis has historically been a challenging disorder to diagnose secondary to its non-specific symptoms and multi-system nature of organ involvement. Since the description of Kviem test in 1941, the diagnostic investigations have evolved substantially over time. We have witnessed refinement of the procedures to detect granulomatous inflammation with increasing utilisation of image guided modalities and more recently Transbronchial Lung Cryo-biopsy with an acceptable diagnostic yield.

Methods: In this review, we aim to describe the utility of diagnostic techniques over the decades and propose an algorithm to help General Physicians as well as Pulmonologists. We used search terms including Sarcoidosis, Diagnosis, Transbronchial as well as endobronchial biopsy, Ultrasound guided core biopsy, Endobronchial ultrasound, Transbronchial Lung Cryo-biopsy, Fine Needle Aspiration as well as peripheral lymph node biopsy.

Results: There has been significant advancement in the diagnostic techniques with improvement in the diagnostic yield for histological confirmation of Sarcoidosis.  clinical evidence and diagnostic utility of salient diagnostic investigations has been evaluated in this review. The description of diagnostic methods and clinical evidence is deliberately kept brief. Ultrasound guided core biopsy of cervical lymph nodes (even in the absence of palpable glands) should be considered as least invasive test in suspected cases of mediastinal sarcoidosis. Transbronchial Lung Cryo-biopsy is relatively recent development in the diagnostic pathway and is an advantageous tool when lung parenchymal abnormalities are coupled with lack or minimal mediastinal and or hilar adenopathy. 

Conclusion: We propose a diagnostic algorithm for patients with suspected Sarcoidosis. The choice of investigation should be decided following discussion in a multi-disciplinary meeting. In appropriate clinical/radiological setting and expertise, core biopsy of cervical lymph nodes should be considered the first line investigation as it may prevent the need for more invasive bronchoscopic procedures. However, in the absence of mediastinal/cervical lymphadenopathy, Cryobiopsy (if available) should be considered, in preference to more invasive thoracic surgical procedure (s) associated with higher morbidity and mortality.