Imaging review of lipomatous musculoskeletal lesions

Abstract

Lipomatous lesions are common musculoskeletal lesions that can arise within the soft tissues, bone, neurovascular structures, and synovium. The majority of these lesions are benign, and many of the benign lesions can be diagnosed by radiologic evaluation. However, radiologic differences between benign and malignant lipomatous lesions may be subtle and pathologic correlation is often needed. The use of sonography, computed tomography (CT), and magnetic resonance imaging (MRI) is useful not only in portraying fat within the lesion, but also for evaluating the presence and extent of soft tissue components. Lipomas make up most soft tissue lipomatous lesions, but careful evaluation must be performed to distinguish these lesions from a low-grade liposarcoma. In addition to the imaging appearance, the location of the lesion and the patient demographics can be utilized to help diagnose other soft tissue lipomatous lesions, such as elastofibroma dorsi, angiolipoma, lipoblastoma, and hibernoma. Osseous lipomatous lesions such as a parosteal lipoma and intraosseous lipoma occur less commonly as their soft tissue counterpart, but are also benign. Neurovascular and synovial lipomatous lesions are much rarer lesions but demonstrate more classic radiologic findings, particularly on MRI. A review of the clinical, radiologic, and pathologic characteristics of these lesions is presented.

Imaging of liposarcomas for clinicians: Characteristic features and differential considerations

“…The most common subtype of LPS, the spectrum of WD/DD LPS, accounts for more than half of all LPS cases . WD/DD LPS is characterized by hallmark amplification of 12q13‐15, which contains several important genes such as MDM2 and CDK4.…”

“…The lesions have varying degrees of enhancement. The “feathery” enhancement pattern of myxoid lesions can be seen, but cannot be used to differentiate myxoid LPS from other lipomatous or myxoid lesions . Limited studies on differentiating low‐grade (predominantly myxoid) LPSs from more aggressive round cell types have yielded some differentiating factors.…”

“…Pleomorphic LPS resemble other high‐grade sarcomas on imaging and contain little to no fat attenuation on CT or fat signal on MRI (Figure ). They are often large, multinodular, and well‐defined masses . Hemorrhage and necrosis can lead to areas of heterogeneity on CT and MRI .…”

Radiomics and Machine Learning Differentiate Soft-Tissue Lipoma and Liposarcoma Better than Musculoskeletal Radiologists

“…is overlap [16] explains that despite the usefulness of MRI findings for the preoperative diagnosis, immuno-histochemical tests such as MDM2 and CDK4 should be considered in the majority of cases [17]. e presence (or absence) of MDM2 and CDK4 is gathered by biopsy or resection which may be technically difficult to perform mainly for deep lesions.…”

A Male Patient With Breast Hamartoma: An Uncommon Finding

“…Sonographically, a lipoma may present as an echogenic mass with or without posterior acoustic enhancement. Fine linear striations parallel to the skin can also be seen in large lesions [13]. Compared with breast hamartomas, lipomas lack the mixed glandular and fibrous tissue and have a more predominantly adipose composition.…”