44. NRDS

Overview of the slide

Staining: PAS

Organ: Lung

Description:

The lung parenchyme look odd, and there are much fewer (open) alveoli than normal. The alveoli that are present are covered by a hyaline “membrane”.

Diagnosis: Neonatal respiratory distress syndrome

The area between the open alveoli contains many atelectic alveoli

Causes:

• Lack of pulmonary surfactant

Theory:

In NRDS are most alveoli atelectic (collapsed), which is why so few alveoli are visible and why the lung parenchyme looks “denser”. The atelectasis damages the alveolo-capillary membrane, increasing the permeability of it, which allows fibrous exudate to enter the alveoli. It is this exudate that forms the hyaline membranes.

RBCs enter the alveoli when the alveolo-capillary membrane is damaged.

Hyaline membrane covering the wall of the alveolus