Histopathologic and Genetic Features of Alveolar Capillary Dysplasia with Atypical Late Presentation and Prolonged Survival

Abstract

Alveolar capillary dysplasia typically presents with neonatal pulmonary hypertension and early mortality. However, there is growing evidence for a subset of disease with atypical late onset and/or prolonged survival. Here, we present the variable clinical, genetic, and pathology findings of 4 such patients.

Keywords: ACD; FOXF1; MPV; case report.

Figure 1; online

Open lung biopsies with H&E and CD31 staining of patient 1 (A and B) age 4 months and patient 3 (C and D) age 5 weeks. Typical features of ACD are seen in both patients, but are much milder in patient 1. The atypical finding of double-layered capillaries is noted with green double arrows. Abbreviations: alveolus (Al), arteriole (Ar), bronchiole (Br), and vein (Ve).

Figure 2

Open lung biopsies and explant or post-mortem with H&E staining for patient 2 (A and B) ages 5 weeks/4months and patient 4 (C – F) ages 3 weeks/10 months. Both patients demonstrate interval alveolar expansion but to a lesser extent than patient 4. Patient 4 also demonstrates a very unusual finding of severe intimal expansion with foamy macrophages in many vessels with near complete obliteration of the arteriolar lumen (E and F, outlined in black dashed lines with margins of vessel outlined in gray dashed line). Abbreviations: alveolus (Al), arteriole (Ar), bronchiole (Br), foamy macrophage (Fo), lumen (Lu), and vein (Ve).