Which microscopic findings are characteristic of lung transplantation rejection, grade C?

Updated: Jun 06, 2019
  • Author: Aliya N Husain, MBBS, MD; Chief Editor: Philip T Cagle, MD  more...
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Answer

Answer

Although often difficult to diagnose on a transbronchial biopsy, BO is the characteristic histologic feature of grade C chronic rejection. In the early phase, the fibrosis is loose and often contains mononuclear inflammatory cells. Later, dense eosinophilic fibrosis is present in the bronchiolar submucosa, resulting in luminal occlusion. Destruction of smooth muscle of the airway wall may be present. Distal airspaces often reveal mucostasis with foamy histiocytes and lipoid pneumonia, which may be a histologic clue when BO is not seen in biopsy material.

Transbronchial biopsies are insufficiently sensitive for the detection of obliterative bronchiolitis, and a diagnosis of BO may require a wedge biopsy. Many clinicians want to know if the fibrosis contains inflammatory cells so that they can be targeted by appropriate treatment; thus, the 1996 grading is preferred in this setting.

  • C0: No BO seen

  • Ca (C1R): Asymmetric or concentric submucosal fibrosis causing partial or complete airway obstruction with inflammation (see image below)

    Lung transplantation-related pathology. Bronchioli Lung transplantation-related pathology. Bronchiolitis obliterans (chronic rejection) is revealed: The patient underwent retransplantation for chronic rejection, which is seen here as eccentric fibrosis partially occluding the airway lumen. Note the presence of scant inflammatory cells and plump fibroblasts in the lesion (hematoxylin and eosin [H&E], 100x).
  • Cb (C1R): Asymmetric or concentric submucosal fibrosis causing partial or complete airway obstruction without inflammation


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