Resolution versus Reliability: Interpreting Ultra-High-Frequency Ultrasound in Melanoma Recurrence Detection [Letter]

We read with great interest the study by Russo et al 1 The authors are to be commended for addressing a clinically relevant and technically challenging problem, namely the detection of clinically occult local recurrence in melanoma excision scars using ultra-high-frequency ultrasound (UHFUS).By systematically evaluating micrometric-resolution morphological features and Doppler vascular signals, the study provides valuable insight into the potential of advanced ultrasound techniques to detect subclinical disease within postoperative tissue.A key strength of the work lies in its pragmatic and technically structured design, incorporating high-frequency transducers, standardized acquisition protocols, and a clearly defined semeiotic classification framework; however, future studies would benefit from larger, multicenter cohorts and comparative evaluation with conventional imaging modalities to strengthen the generalizability of these findings.From a technical imaging perspective, the study effectively exploits the resolution-penetration trade-off inherent to ultrasound physics.Transducers operating at 48-70 MHz provide axial resolutions approaching 30-60 m, enabling visualization of fine dermal architecture and small hypoechoic nodules that are not resolvable with conventional 10-18 MHz probes. 2 However, this increased resolution is accompanied by limited penetration depth and increased susceptibility to attenuation and acoustic shadowing, particularly in fibrotic or collagen-dense scar tissue.In such environments, acoustic impedance mismatches and anisotropic collagen alignment may produce signal heterogeneity and speckle variation, potentially mimicking or obscuring true pathological findings.Furthermore, the shallow penetration restricts assessment of deeper subcutaneous planes, which may harbor early recurrence beyond the effective imaging window.Optimization strategies such as compound imaging, dynamic range adjustment, and probe angulation may partially mitigate these limitations, although they introduce additional operator dependency.The integration of Doppler imaging adds a functional dimension by detecting low-flow vascular signals associated with tumor neoangiogenesis.Nevertheless, Doppler sensitivity at these frequencies introduces important interpretative challenges.Low pulse repetition frequency (PRF) and high gain settings-required to detect slow microvascular flow-are inherently prone to motion artifacts, blooming artifacts, and noise amplification. 3 At ultra-high frequencies, even minimal transducer motion may generate spurious signals due to increased system sensitivity.In postoperative scars, vascular signals may also arise from benign processes such as inflammation, granulation tissue, or fibroblast-driven remodeling rather than true tumor recurrence.These overlapping hemodynamic signatures reduce specificity and may account for false-positive findings.Emerging approaches such as contrast-enhanced ultrasound (CEUS) and advanced microvascular imaging techniques may improve specificity by enabling better characterization of vascular architecture and perfusion patterns. 4,5nother important technical consideration relates to image interpretation.The semeiotic classification proposed by the authors, while structured, relies on qualitative assessment of morphology and vascularity without clearly defined quantitative thresholds.In high-resolution ultrasound, subtle variations in echogenicity, lesion margins, and vascular patterns are highly sensitive to acquisition parameters, including gain, focus, and probe pressure.This raises the possibility that minor technical