Correct!
1. Relapsing polychondritis
Relapsing polychondritis (RPC) is an autoimmune disorder characterized by recurrent inflammation of cartilaginous structures, particularly the ear, nose, joints, larynx, and tracheobronchial tree. Auto-antibodies against cartilage and types I, II and III collagen have been shown to be present in RPC. The recurrent inflammatory episodes result in cartilage destruction, loss of structural integrity, and fibrosis. Laryngeo-tracheobronchial involvement is the presenting feature of RPC in only 10% of patients, but eventually develops in nearly 50% of patients, and may carry a poorer prognosis. Men and women are equally affected in many reports, with more recent data suggesting a slight female preponderance, with the average age of disease presentation in the 5th decade, although a wide age of presentation is known. Cardiovascular disease and vasculitis may occur in some patients. The diagnosis of RPC can be made when 3 or more of the following are present (McAdam’s criteria): bilateral auricular chondritis, nasal chondritis, ocular inflammation, respiratory tract chondritis, audiovestibular damage, or a seronegative, non-erosive inflammatory polyarthropathy. Alternatively, the diagnosis of RPC can be made when one or more of the above symptoms are present, in combination with histopathological proof of chronic inflammation at an involved site, or two or more of the foregoing symptoms are present, with a therapeutic response to corticosteroid or dapsone therapy. Finally some have suggested that the diagnosis of RPC may be established when inflammation is proven in 2 of these 3 sites: nose, ears, or respiratory tract, or at one of these sites in addition to two or more of the following symptoms: ocular inflammation, vestibular dysfunction, a seronegative inflammatory arthropathy, or hearing loss.
In this case, features of Wegener’s granulomatosis (aka granulomatosis with polyangiitis, ANCA-associated granulomatous vasculitis) are not noted, and the thoracic CT appearance (see below) is not suggestive of this disorder. Similarly, both amyloidosis and tracheobronchopathia osteochondroplastica can cause long-segment tracheobronchial stenoses at thoracic CT, but typically both produce morphologies distinct from that seen in this patient (see farther on). Finally, ulcerative colits can produce airway disease, and this patient does have a history of such, but the more common large airway manifestations of thoracic involvement with this disorder are bronchiectasis or focal large airway thickening. Long-segment airway thickening can occur in ulcerative colitis, but a CT morphology distinct from that seen in this patient is expected (see farther on).
The CT findings in this patient are best described as a long segment tracheobronchial stenosis with malacia. A number of disorders may present with long segment tracheobronchial stenoses, some with malacia, at thoracic CT, including Wegener’s granulomatosis (aka granulomatosis with polyangiitis, ANCA-associated granulomatous vasculitis), amyloidosis, sarcoidosis, tracheobronchopathia osteochondroplastica, RPC, saber-sheath trachea, tracheobronchial malacia, and inflammatory blower disease. CT may often effectively discriminate among these disorders by noting a few key features (see Table 1).
Table 1. CT Features of Long-Segment Tracheobronchial Stenoses
† Focal disease commonly results from trauma or prior intubation. Focal disease usually produces wall thickening; diffuse disease may not show wall thickening. Malacia most evident with chronic causes, such as late post-intubation stenoses
* Malacia not typical
‡ Few data available, but not specifically described
Diagnosis: Relapsing polychondritis
Which of the following regarding the thoracic CT appearance of the tracheobronchial thickening in relapsing polychondritis is false?