Lipedema is a chronic condition affecting approximately 12.3% of women in Brazil [ 1 ], clinically characterized by symmetrical fat accumulation in the arms and legs, sparing trunk, hands, and feet. Symptoms include persistent evening pain, heightened sensitivity to touch, easy and spontaneous bruising, a lack of response to weight loss interventions, and painful edema that does not improve with limb elevation (Trendelenburg position) [ 2 ]. In contrast to lymphedema, which is a disorder of the lymphatic system, lipedema does not present with pitting edema in its early stages, nor does it show a positive Stemmer’s sign.

The exact pathophysiology remains uncertain, though genetic and hormonal factors have been proposed as potential contributors [ 2 , 3 ]. Obesity, while not considered a direct cause, must be carefully differentiated from lipedema to avoid diagnostic confusion. Clinical parameters, including body mass index (BMI), abdominal circumference, and impedance, are commonly employed to facilitate accurate differentiation [ 4 , 5 ]. Due to significant overlap with symptoms of lymphedema, accurate clinical diagnosis of lipedema can be challenging.

Accurate differentiation between lipedema and lymphedema is essential for effective patient management. This distinction relies primarily on clinical history and detailed physical examination assessing specific signs. Lymphedema typically presents with painless edema, a positive Stemmer’s sign (inability to pinch the skin at the base of second toe or finger), and a positive Godet’s sign (persistent indentation upon skin compression). Additionally, lymphoscintigraphy in lymphedema demonstrates altered lymphatic flow, such as reduced or obstructed transport [ 4 , 6 ].

Existing classifications of lipedema are primarily based on anatomical distribution ( Figure 1 ) [ 2 , 6 , 7 ] or functional staging ( Table 1 ) [ 2 , 3 , 8 ]. However, these approaches do not sufficiently account for other relevant factors such as disease severity, degree of inflammation, and extent of fibrosis, thus limiting their effectiveness in guiding clinical management. Given these limitations, recent research has aimed at developing a classification system that integrates ultrasonographic findings with clinical features, potentially improving diagnostic accuracy and interobserver reproducibility in the evaluation of lipedema.

Source: Adapted from Herbst, 2012.

This work proposes a new ultrasonographic classification for lipedema that describes radiological findings based on structural changes in dermis and hypodermis.

Ultrasound images of the dermis and hypodermis from 34 female patients, 20 - 47 years old, forwarded for evaluation of lipedema, were retrospectively analyzed. Examinations were performed in 2024, utilizing the ultrasonographic technique described by Amato et al. [ 9 ] ( Table 2 ). The study was approved by our institutional review board, and all patients gave informed consent. Patients diagnosed with lipedema who presented concomitant obesity were excluded from this analysis. Imaging was performed using high-frequency linear transducers (10 - 15 MHz) on GE Logiq S8, Philips Affiniti 70, and Samsung V6 systems in B-mode, with a minimum depth of four centimeters, in a limb longitudinal orientation, emphasizing the medial proximal leg, lateral mid-proximal thigh and posterior distal thigh.

Source: Amato et al. 2021 [ 9 ].

A qualitative analysis was conducted to identify morphological changes in the dermis and hypodermis. These patterns were subsequently used to develop a classification system, correlating structural findings with possible disease progression.

Qualitative analysis first characterized the normal ultrasonographic appearance of the dermis and hypodermis, identified as “layered hypodermis pattern”, defined by linear hyperechoic septa, regularly interspersed within the subcutaneous tissue ( Figure 2 ). Ultrasonographic images from obese patients, without lipedema, demonstrated thickening of the subcutaneous tissue (SCT), predominantly within the deep hypodermis, while maintaining preserved linear septa and a layered architecture ( Figure 3 ).

Subsequent analysis of patients with lipedema revealed four distinct ultrasonographic patterns in the dermis and hypodermis. These observed patterns were organized into the Lipedema Dermal and Hypodermal Classification (LDHC), subdivided into LDHC 1 - 4. Hypodermal findings included the evaluation of septa and hyperechoic nodules, whereas dermal assessment primarily focused on the dermis-hypodermis junction and dermis thickening.

The LDHC classifications are based on distinct ultrasonographic findings that describe varying degrees of tissue disruption. LDHC 1 shows a preserved architecture with linear, thin septa and no hyperechoic nodules, indicating minimal disruption ( Figure 4 ). In LDHC 2, the architecture appears bulging with irregular septa and around 50% disruption, but hyperechoic nodules remain absent ( Figure 5 ). LDHC 3 presents with a bulging deep hypodermis and disorganized superficial hypodermis, irregular septa, and the presence of hyperechoic nodules, along with asymmetric thickening of the dermis and an irregular dermis-hypodermis junction ( Figure 6 ). LDHC 4 displays a “marbled” pattern with more than 50% disruption of the septa, branching and verticalization, and asymmetric dermal thickening. Further, hyperechoic nodules are absent, and the dermis-hypodermis junction presents a “serrated” pattern ( Figure 7 ). These classifications reflect a spectrum of increasing disruption and structural disorganization in the tissue.

Current functional classification primarily emphasizes clinical signs involving the skin, subcutaneous tissue, and lymphatic system. This approach does not clearly address inflammatory and fibrotic changes associated with tissue remodeling and functional impairment.

Standardized imaging protocols for lipedema are essential to improve diagnostic accuracy and minimize unnecessary imaging studies. Ultrasound has become widely recognized as a valuable imaging modality for evaluating soft tissue disorders, offering a cost-effective and accessible alternative to magnetic resonance imaging (MRI) and other advanced imaging techniques [ 10 , 11 ].

The proposed classification provides a novel framework integrating ultrasonographic findings with tissue remodeling processes, such as inflammation and fibrosis, features inadequately addressed by existing classifications [ 3 , 8 ]. Nevertheless, the LDHC is preliminary, and multicenter studies are necessary to validate its clinical applicability, reproducibility, and correlation with histopathology and clinical outcomes.

Strengths and Implications

Limitations and Future Directions

Prospective multicenter studies should involve standardized clinical criteria for patient selection and include control cohorts (obese and lymphedema patients) to establish the specificity or LDHC features. Utilizing standardized high-frequency ultrasound (10 - 15 MHz) protocols targeting predefined anatomical regions will help ensure reproducibility and consistency. Validation should encompass intra and interobserver agreement (Cohen’s kappa) and analyses correlating ultrasonographic findings with clinical severity scores and histopathologic features from surgical samples. Additionally, longitudinal assessments are commended to evaluate LDHC’s ability to track disease progression and therapeutic response.

Lipedema remains underdiagnosed due to limited awareness and inconsistent diagnostic criteria. This study introduces a qualitative ultrasound classification system to characterize structural patterns in dermis and hypodermis of lipedema. The proposed classification aims to assess procedural risks, guide optimal treatment decisions, and evaluate treatment efficacy.

Although preliminary, the LDHC highlights the potential of ultrasound as a diagnostic tool for lipedema. Multicenter studies could complement the validation process and help assess the classification and its reproducibility. Validation if ultrasonographic findings patterns truly correspond to the clinical progression of the disease. These steps will refine its clinical utility, potentially improving patient care and outcomes.