Relapsing polychondritis: tracheobronchial involvement and differential diagnoses

This review is describing the diagnostic and therapeutic approach to tracheobronchial involvement in relapsing polychondritis (RP), with a focus on differential diagnoses of inflammatory origin. RP is a systemic auto-immune disease that mainly affects cartilage structures, progressing through inflammatory flare-ups between phases of remission and ultimately leading to deformation of the involved cartilages. Besides the damage of auricular or nasal cartilage, tracheobronchial and cardiac involvement are the most severe, and can seriously alter the prognosis. Tracheobronchial lesions are assessed through a multimodal approach. Mapping of tracheal lesions is achieved using dynamic thoracic imaging and flexible bronchoscopy. Measurement of pulmonary function (with new emphasis on pulse oscillometry) is useful to diagnose obstructive ventilatory impairment, and can be used to follow RP patients, after therapeutics implementation. Diagnosis can be difficult in the absence of specific diagnostic tools, especially because there is a large number of differential diagnoses, in particular inflammatory diseases. Nuclear imaging can help with detection of metabolic activity on involved cartilages, leading to sharpen the final diagnosis. The prognosis has improved, thanks to the upgraded interventional bronchoscopy techniques, and the development of immunosuppressant including targeted therapies, such as tumor necrosis factor-α (TNF-α) inhibitors, offering patients several treatment options, in addition to supportive care.