Although the usual morphology is usually “in cluster”, this unique and sessile papilloma, identical in color to the mucosa, seems to be monitored from the trachea at the entrance to the main bronchi.
The longitudinal folds are preserved parallel but very accentuated and somewhat “separated” in this pulmonary atelectasis by extrinsic compression. Recall that in the trachea only the malignant conditions contiguous to its posterior wall “accentuate and separate” their folds, while the compressions of nonmalignant causes produce the bulge of the wall and the folds can be separated but not accentuated or “sink” in the mucosa, because it is not infiltrated but has only been pushed towards the tracheal lumen.
Distribution anomaly: Tracheal bronchus.
Part of the right upper lobe is ventilated thanks to a bronchus that has shifted during the embryonic phase of lung development so that it is born directly from the trachea.
Sometimes, this bronchus only leads to the apical segment of the right upper lobe and is, in these cases, a “supernumerary” bronchus.
It can be associated to the fusion of cervical vertebrae (syndrome of Klippel Feil).