Disruption of the dermal matrix secondary to photoaging is one of the proposed etiologies for rosacea. Matrix metalloproteinase-1-mediated collagen degeneration has been shown to impact endothelial cells, leading to the formation of vascular tubes resembling telangiectatic lumina. We performed a case-control study to examine the relationship between clinical presentation, collagen degeneration, and microvascular changes between 5 patients with erythematotelangiectatic rosacea ages 47-83 and 5 controls matched by age ±5 years and race. Biopsies were taken of telangiectasias from rosacea patients and of normal facial skin from controls. Samples were stained with Picrosirius red for collagen visualization and CD31 for vessels. Image J and SPSS-25 were used for image analysis. When examining the papillary and reticular dermis of Picrosirius red-stained slides, samples from controls displayed significantly greater mean collagen content (19.603% ±8.821%) compared to rosacea patients (16.812% ±7.787%, p=0.030). Examination of the CD31-stained sections demonstrated a significantly higher mean microvessel density in rosacea patients (4.775 E-5 ±1.493 E-5 µm-3) compared to controls (2.559 E-5 ±8.732 E-6 µm-3, p=0.004) and significantly higher mean vessel lumen area in rosacea (491.710 ±610.188 µm2) compared to controls (347.879 ±539.624 µm2, p=0.003). By individual patient-control pair, 5/5 pairs had increased microvessel density and decreased collagen content in rosacea patients compared to controls. 3/5 pairs demonstrated significantly increased mean lumen area in rosacea individuals.  No significant correlations were identified between the histologic findings and clinical severity grading of rosacea or photoaging.  However, we identified a direct relationship between decreased collagen and increased microvessel size and density in rosacea patients.  These structural changes may represent early aberrations that develop in this condition and provide a link between photodamage and rosacea.

The role of photo-induced collagen degeneration in the development of telangiectasias in rosacea