From the Guidelines
Benign lipomas are best diagnosed through a combination of physical examination and ultrasound imaging, as this approach can accurately identify characteristic features of lipomas and distinguish them from other soft tissue masses. A healthcare provider will first perform a physical examination, feeling the lump to assess its characteristics, such as being soft, movable, and painless, located just under the skin, and having a doughy or rubbery texture 1. If the physical examination suggests a lipoma, ultrasound is commonly used for confirmation, as it can demonstrate characteristic features such as no or minimal acoustic shadowing, no or minimal vascularity, and simple curved echogenic lines within an encapsulated mass 1. According to a study published in the Journal of the American College of Radiology, ultrasound has a high sensitivity and specificity for diagnosing superficial soft-tissue masses, including lipomas, with an overall sensitivity and specificity of 94.1% and 99.7%, respectively 1.
Some key points to consider in the diagnosis of benign lipomas include:
- Ultrasound is a useful initial imaging study for suspected superficial or subcutaneous lipomas, especially for small superficial lesions 1.
- MRI or CT scans may be necessary for larger or deeper lipomas, or when ultrasound imaging is inconclusive 1.
- Biopsy is usually only needed if there are concerning features such as rapid growth, pain, or unusual appearance that might suggest a different type of tumor 1.
- The majority of soft-tissue lumps are likely to be diagnosed as benign lipomas, and patients can be safely reassured 1.
- In cases where the diagnosis is uncertain, or when differentiating between lipoma and atypical lipomatous tumor (ALT), MRI with expert review or molecular demonstration by fluorescence in-situ hybridisation of amplification of the MDM-2 cell cycle oncogene may be necessary 1.
Overall, the diagnosis of benign lipomas should prioritize a combination of physical examination and ultrasound imaging, with further testing and evaluation as needed to confirm the diagnosis and rule out other potential causes.
From the Research
Diagnosis of Benign Lipomas
Benign lipomas are diagnosed using various methods, including:
- Imaging techniques such as high-frequency ultrasound 2 and MRI 3, 4
- Clinical evaluation of the mass, including size and location 3
- Radiographic features, such as septations, nonfat nodules, heterogeneity, and ill-defined margins 3, 4
- Core needle biopsy (CNB) for masses larger than 3-5 cm or with high-risk radiographic features 3
Imaging Techniques
Imaging techniques play a crucial role in the diagnosis of benign lipomas. High-frequency ultrasound is used to assess the size of lipomas and monitor treatment-induced changes 2. MRI is used to evaluate the qualitative features of lipomas and distinguish them from atypical lipomatous tumors (ALTs) 4.
Clinical Evaluation
Clinical evaluation of the mass is also important in diagnosing benign lipomas. The size and location of the mass are taken into consideration, with masses larger than 5 cm being more likely to require preoperative imaging and CNB 3.
Biopsy
Core needle biopsy (CNB) is recommended for masses larger than 3-5 cm or with high-risk radiographic features 3. However, the results of one study suggest that lipomatous masses smaller than 5 cm without concerning clinical characteristics do not require preoperative imaging or CNB 3.
Treatment Options
Once diagnosed, benign lipomas can be treated using various methods, including: