DISCUSSION
These case reports demonstrate that patients with cough, chest tightness
and fever may have inflammation of the trachea and main bronchi without
abnormalities in other organs, which can constitute the pathogenesis of
various clinical conditions. Previous reports have presented some cases
of inflammation of the trachea and main bronchi with abnormalities in
the lung and/or other organs, such as a case of IgG4-related disease
[3-5] and a case of granulomatosis with polyangiitis [6,7].
However, there is no past report on inflammation localized to the
trachea and main bronchi. We referred to this presentation as
tracheobronchitis in the title because these three cases presented with
lesions confined to the trachea and main bronchi.
In this series, CASE 1 showed eosinophilic and plasmacytic infiltration
based on bronchial biopsy specimens, suggesting an allergic mechanism.
For CASE 2, mild IgG4-positive plasmacytic infiltration based on
bronchial biopsy specimens was observed, indicating possible localized
IgG4-related disease. However, this is not definitive because
IgG4-positive cells are also present in other diseases, such as
vasculitis. CASE 3 exhibited palisading granuloma and multinucleated
giant cells in the bronchial biopsy specimens, which led us to suspect a
subtype of localized granulomatosis with polyangiitis. Although
inflammation of the central airway was observed in all three cases,
there is a distinct possibility that these three diagnoses had different
underlying mechanisms.
Previously, it was not commonly considered that inflammation of the
large airways would produce such diffuse wall thickening. However, in
this report, we show that tracheobronchitis can cause various types of
inflammation with wall thickening. It is suspected that
tracheobronchitis is not a rare condition; however, it is likely less
noticeable. More attention should be paid to the wall of the trachea and
main bronchi during the interpretation of chest CT findings in patients
with chest symptoms or fever to fully understand their clinical
condition. If thickening of the airway wall is detected, we should
investigate the cause of thickening with bronchial or tracheal biopsy
using flexible bronchoscopy. The pathological findings in the biopsy
tissue can reveal large airway conditions in these patients and guide
appropriate treatment strategies.
We hope that additional cases with similar findings are reported in the
future to further our understanding of this clinical condition.