Emerging phenotypes of sarcoidosis based on 18F-FDG PET/CT: a hierarchical cluster analysis.

Objectives

In sarcoidosis, the definition of organ involvement with traditional means appears laborious and somewhat controversial, and phenotyping by the above overlapping. 18F-FDG PET/CT defines disease extent by activity more precisely, and may result in a better understanding of sarcoidosis disease behavior and phenotypes expression. We hypothesized that 18F-FDG PET/CT could add in the phenotyping of sarcoidosis patients by unveiling in detail sites of involvement even in clinically and physiologically silent disease.

Methods

This study was designed to investigate the role of 18F-FDG PET/CT in phenotyping sarcoidosis using cluster analysis by adding this new means in the routine work-up of 195 sarcoidosis patients of a single academic center.

Results

18F-FDG PET/CT succeeded to identify despite the random distribution of the disease, an ordered stratification into 4 phenotypes: I) thoracic nodal hilar-mediastinal, II) thoracic nodal hilar-mediastinal and lungs, III) an extended thoracic and extra-thoracic only nodal phenotype including inguinal-abdominal-supraclavicular stations, and IV) all the above plus systemic organs and tissues such as muscles-bones-spleen and skin.

Conclusion

Though further studies are necessary to confirm findings as patterns of disease behavior; the proposed phenotypes may prove useful in the design of future studies with homogeneous cohorts facilitating in sarcoidosis patients a personalized medicine approach.