The aim of this observational study is to evaluate the diagnostic value of multimodal ultrasonography in differentiating between lymphedema and lipedema. Differentiating these two chronic conditions based solely on clinical examination can be challenging due to overlapping symptoms. This study will utilize various non-invasive ultrasound techniques-including B-mode ultrasound, strain elastography, power Doppler, and quantitative ImageJ analysis-to compare tissue characteristics among patients with lymphedema, patients with lipedema, and healthy controls. The goal is to identify reliable, non-invasive imaging biomarkers that can facilitate early and accurate diagnosis, thereby optimizing patient management.

Lymphedema and lipedema are distinct pathological entities that often present with similar clinical features, particularly in the lower extremities. Accurate differential diagnosis is crucial for appropriate therapeutic intervention. While modalities like lymphoscintigraphy serve as standard diagnostic tools for lymphedema, they are invasive and not universally accessible. High-resolution ultrasonography provides a practical, non-invasive alternative for tissue assessment.

This cross-sectional, observational study will recruit participants and categorize them into three groups: a lymphedema group, a lipedema group, and a healthy control group. Comprehensive multimodal ultrasound evaluations will be performed on all participants. The assessment protocol includes:

B-mode Ultrasonography: To measure the thickness of the dermis and subcutaneous tissue layers.

Strain Elastography: To evaluate the biomechanical properties and relative stiffness of the affected tissues.

Power Doppler: To assess the local microvascularity and blood flow patterns.

ImageJ Software Analysis: To perform quantitative pixel-based echogenicity evaluation of the ultrasound images.

By systematically comparing these ultrasonographic parameters across the three groups, this study aims to establish standard, reproducible imaging criteria. The primary objective is to determine which specific ultrasound modalities, or combinations thereof, offer the highest diagnostic accuracy in differentiating lymphedema from lipedema in clinical practice.

Inclusion Criteria:

Individuals aged 18 to 75 years.

Clinical diagnosis of lower extremity lymphedema (for the lymphedema group).

Clinical diagnosis of lower extremity lipedema (for the lipedema group).

Healthy individuals with no history or clinical signs of chronic lower extremity edema (for the control group).

Exclusion Criteria:

Presence of active local infections, such as cellulitis or erysipelas, in the lower extremities.

History of deep vein thrombosis (DVT) or severe chronic venous insufficiency.

Systemic conditions that can cause secondary edema, including congestive heart failure, chronic kidney disease, or severe hepatic impairment.

Previous surgical interventions on the affected lower extremities, including liposuction, lymphatic reconstructive surgery, or major orthopedic surgeries.

Active malignancy or currently undergoing radiotherapy/chemotherapy.

Pregnancy or lactation.

The study population consists of patients presenting to the Physical Medicine and Rehabilitation outpatient clinic with complaints of lower extremity swelling, diagnosed clinically with either lymphedema or lipedema. A healthy control group, matched for general demographic characteristics, will be recruited from volunteers without any lower extremity pathologies.

Individual participant data (IPD) will not be shared publicly to maintain participant confidentiality and in accordance with the policies of the institutional ethics committee. However, the study protocol and statistical analysis plan may be available upon reasonable request to the principal investigator.