Ultrastructural aspects of pseudoxanthoma elasticum

Abstract

We report the ultrastructural findings in a case of a 72-year-old black woman with confluent yellowish papules in the cervical region. She had no comorbidities. Ophthalmological examination, electrocardiogram, and echocardiogram were normal. Hematoxylin-eosin staining of the affected skin showed strong alterations in the mid-dermis with irregular clumps of eosinophilic material and loss of the normal parallel arrangement of collagen bundles. Orcein staining revealed that the elastic fibers lost their normal linear configuration, showing clump fragmentation, sometimes forming square structures. Transmission electron microscopy showed aberrant elastic fibers with an irregular outline and heterogenic inner structures. We also observed small elastic fibers. Collagen fibers showed a normal structure with irregular distribution. Scanning electron microscopy revealed important disorganization of collagen fibers and small stone-like deposits measuring around 5 µm associated with bigger structures ranging from 10-16 µm. Higher magnification revealed that these small stone-like structures were sometimes polyhedral-shaped or squared.

Figure 1

Cervical involvement with yellowish papules

Figure 2

Light microscopy with HE staining. A and B - low magnification (X100) showing eosinophilic degeneration of the mid-dermis (arrows). Note the papillary and deep dermis showing less intense changes (asterisks). C - detail of the mid-dermis showing intense eosinophilic changes (X400)

Figure 3

Light microscopy with orcein staining. A - and B - low magnification (X100) showing degeneration of the mid-dermis, confirming that the papillary and deep dermis show less intense changes. C - detail of the mid-dermis showing elastic tissue changes with clumping and square structures (inset with detail of the clumping) (X400).

Figure 4

Transmission electron microscopy. A - irregular and clumped elastic fiber (X7,000). B - area with smaller elastic fibers with a square outline (arrows) and a collagen bundle (CB) (X7,000). C - large irregular elastic fibers near to lose collagen fibers (C) (X7,000). D - detail of an elastic fiber showing irregular distribution of black dots in its core and a collagen bundle in cross section demonstrating normal collagen fibers (CB) (X20,000)

Figure 5

Scanning electron microscopy. A - low magnification with irregular distribution of collagen fibers (C) and deposition of small structures with around 5 µm and bigger ones over 10 µm (X1,500). B - detail of the stone-like structures seen in the mid-dermis (X3,000). C - collagen bundle (CB) with two small stone-like structures (X4,500). D - detail of the small structures, some with a square outline (arrow) (X6,000)