Vascular Characteristics of Treatment-resistant and-responsive Actinic Keratosis Identified with Dynamic Optical Coherence Tomography

Treatment-resistant actinic keratosis (AK) is of concern in clinical practice, often requiring retreatment. Microvascular assessments might help differentiate treatment-resistant from treatment-responsive AKs, enabling targeted treatment. Using dynamic optical coherence tomography, AK vascularization was investigated following daylight photodynamic therapy, comparing treatment-resistant with cleared AKs. AKs on face/ scalp were graded according to the Olsen Classification Scheme and scanned with dynamic optical coherence tomography pre-treatment, and 3-and 12-months post-treatment. Employing dynamic optical coherence tomography, total vessel length, mean vessel length, mean vessel diameter, vessel area density, and branchpoint density were quantified. Thirty-eight patients with 62 AKs were enrolled, including 37 AK I, 18 AK II, and 7 AK III. Treatment-resistant AKs displayed a trend toward intensified vascularization compared with cleared AK at baseline (AKs I, II), suggested by higher total vessel length (median 144.0, IQR 104.3–186.6) and vessel area density (median 27.7, IQR 18.4–34.2) than in cleared AK (median 120.9, IQR 86.9–143.0 and median 22.9, IQR 17.3–26.8). Additionally, vascularization in treatment-resistant AK I–II appeared disorganized, with trends toward shorter mean vessel length (median 151.0, IQR 138.5–167.5) and increased branchpoint density (median 3.2, IQR 2.3–3.8) compared with cleared AK (median 160.0, IQR 152.0–169.3 and median 2.6, IQR 2.2–3.0). These findings suggest that dynamic optical coherence tomography holds potential to identify treatment-resistant AKs.