# The Value of High-Frequency Ultrasound in the Evaluation of Cutaneous Rosai-Dorfman Disease: A Case Series and Literature Review

## TL;DR

This study explores how high-frequency ultrasound can help evaluate a rare skin condition called cutaneous Rosai-Dorfman disease, offering a non-invasive way to monitor treatment and guide decisions.

## Contribution

The study introduces high-frequency ultrasound as a complementary non-invasive tool for evaluating and monitoring cutaneous Rosai-Dorfman disease.

## Key findings

- High-frequency ultrasound (HFUS) can delineate dermal and subcutaneous involvement in CRDD cases.
- HFUS can assess lesion morphology, contour regularity, border definition, and vascularity.
- HFUS is useful for monitoring treatment response by showing changes in lesion size and vascularity.

## Abstract

Background and Clinical Significance: Cutaneous Rosai-Dorfman disease (CRDD) is a rare, benign histiocytic proliferative disorder, accounting for approximately 3% of all Rosai-Dorfman disease (RDD) cases. Currently, the diagnosis of CRDD relies on invasive pathological examination due to the absence of reliable non-invasive alternatives. This case series evaluates the potential utility of high-frequency ultrasound (HFUS) as an adjunctive diagnostic tool for CRDD. Case Presentation: We present three CRDD cases, correlating HFUS features with histopathology. All cases showed hypoechoic lesions with varying infiltration depths and morphologies, though no specific diagnostic features were identified. HFUS clearly delineated involvement of the dermal and subcutaneous layers, assessed morphological characteristics like contour regularity and border definition, and evaluated vascularity. This information is crucial for clinical decision-making. HFUS also demonstrated value in therapeutic follow-up. In Case 1, it objectively showed a reduction in lesion size and decreased internal vascularity, providing clear evidence of treatment response. Conclusions: Although HFUS cannot independently diagnose CRDD and histopathology remains the gold standard, it serves as a valuable complementary tool. HFUS allows evaluation of deeper tissue structures, infiltration depth, and vascularity. As a non-invasive modality, it is useful for treatment monitoring, therapy guidance, and prognosis assessment. Integrating HFUS into the CRDD workflow enables more comprehensive and precise management.