Histopathologic study of keloid vascular structures shows the vascular origin pattern of keloid subepidermal vascular network flaps.

Background: Keloid subepidermal vascular network flaps (KSVNFs) have achieved satisfactory results in clinical practice. Through this retrospective study, we further examined keloid vascular structure to better understand vascular origin pattern in KSVNFs.

Methods: Paraffin-embedded keloid tissues were stained for CD31. Distances from keloid subepidermal capillaries to the skin surface were measured. The included angle between the pedicle vessels and skin surface (angle PV), as well as the included angle between the keloid margin and skin surface (angle KM), were also measured. The major and minor axes of the capillary in the central areas of keloid (KDC), adjacent skin (AS) and marginal areas of keloid (KDM) were analyzed, and the major:minor axis ratios (M/m) were calculated. Vessels in KSVNF pedicle sites (KDP) were compared with vessels in adjacent skin as a subgroup analysis.

Results: Twenty-nine keloid specimens in total were collected. Based on 1630 measured data points, the capillary distance to the skin surface was 387.2±96.7 μm. The angle PV was 70.1±36.6°, and the angle KM was 67.0±18.1°. The major axis of the KDM capillaries was significantly longer than that of KDC and AS (both P < 0.001). The major and minor axes were longer in KDP than in AS (both P < 0.001).

Conclusion: Suprakeloidal blood vessels are mainly distributed at a depth of 387.2±96.7 μm from the skin. The subepidermal plexus in KSVNF pedicle sites enters the skin at an acute angle and runs parallel to the keloid margin layer. Vessels in keloid marginal areas had crushed vascular lumen, but vessels in KSVNF pedicles did not.