Lipomatous Soft Tissue Tumors Research Articles

Benign Lipomatous Soft Tissue Tumors in Nigerians: An Analysis of the Clinical and Morphological Features of a Common but Important Entity.

Introduction Benign lipomatous tumors are soft tissue tumors that exhibit a predominant adipocytic phenotype. Lipomas are the archetype and are the most common benign soft tissue tumors in adults but relatively uncommon in children. Their sex incidence is equivocal. They sometimes occur in combination with other mesenchymal elements, giving rise to variants including fibrolipoma, angiolipoma, myolipoma, spindle cell lipoma, chondroid lipoma, osteolipoma, and chondrolipoma. Their clinical significance is mainly due to the cosmetic disfigurement of patients and the differential diagnosis of malignant soft tissue tumors. Occasionally, due to their large size or presence near vital organs, they may cause life-threatening and/or excruciating pressure symptoms. This study was purposed to address the dearth of local studies on the clinical and morphological characteristics of benign lipomatous tumors in Nigerians, to compare these with those of other populations, and to establish baseline data. Materials and methods This was a retrospective study of all benign lipomatous tumors seen in the anatomic pathology and forensic medicine department of Asokoro District Hospital, Abuja, Federal Capital Territory, Nigeria, over an eight-year period. Surgical pathology reports were retrieved for patients' biodata and clinical information. The appropriate slides were retrieved, and reviewed, and new sections were cut where necessary. The tumors were classified according to the 2020 World Health Organization (WHO) guidelines and categorized based on size as small, medium, or giant. The data obtained were analyzed, and the results were presented as tables, bar charts, ratios, and percentages. Results Four hundred and eighteen cases met the inclusion criteria. Of these, 58.4% (244/418), occurred in females, while 41.6% (174/418) occurred in males. The age range was six to 91 years, while the median age was 42 years. The least number of cases, 0.5% (2/418), were seen in patients aged less than 10 years, while the majority, 35.4% (148/418), occurred in the fifth decade, followed by 27.8% (116/418) in the fourth. Size-wise, the majority of tumors, 60% (253/418), were medium, followed by small, 22.8% (95/418). Giant-sized tumors significantly accounted for 16.7% (70/418) of the cases. The diagnostic spectrum comprised conventional lipoma and variants such as fibrolipoma, spindle cell lipoma, pleomorphic lipoma, angiolipoma, chondrolipoma, intramuscular lipoma, and osteolipoma. Lipoma and fibrolipoma dominated with 87.1% (364/418) and 10.0% (42/418), respectively, while the rest accounted for <3%. The majority, 31.8% (133/418), occurred in the back/shoulder region, followed by the lower limb with 18.2% (76/418). Only two cases occurred in the abdominal/pelvic region. More tumors occurred in females in all the regions except the head and neck, which had a male-to-female ratio of 1.5:1. Multiple site tumors were more common in males in a ratio of 2.5:1. Most, 41.1% (39/95), of the small-sized tumors, occurred in the head/neck region, largely involving the face, 48.7% (19/39). Conclusion Our study showed many similarities in the clinical and morphological features of benign lipomatous tumors between Nigerians and other regions of the world. A notable finding, however, was the significantly higher proportion of giant benign lipomatous tumors when compared tostudies from other regions, a finding that warrants further studies.

Evaluation of Classic and Quantitative Imaging Features in the Differentiation of Benign and Atypical Lipomatous Soft Tissue Tumors Using a Standardized Multiparametric MRI Protocol: A Prospective Single-Centre Study in 45 Patients

Discrimination between benign and atypical lipomatous tumors (ALT) is important due to potential local complications and recurrence of ALT but can be difficult due to the often-similar imaging appearance. Using a standardized MRI protocol, this study aimed to rank established and quantitative MRI features by diagnostic value in the differentiation of benign and atypical lipomatous tumors and to develop a robust scoring system. Patients with clinical or sonographic suspicion of a lipomatous tumor were prospectively and consecutively enrolled from 2015 to 2019 after ethic review board approval. Histology was confirmed for all ALT and 85% of the benign cases. Twenty-one demographic and morphologic and twenty-three quantitative features were extracted from a standardized MRI protocol (T1/T2-proton-density-weighting, turbo-inversion recovery magnitude, T2* multi-echo gradient-echo imaging, qDIXON-Vibe fat-quantification, T1 relaxometry, T1 mapping, diffusion-weighted and post-contrast sequences). A ranking of these features was generated through a Bayes network analysis with gain-ratio feature evaluation. Forty-five patients were included in the analysis (mean age, 61.2 ± 14.2 years, 27 women [60.0%]). The highest-ranked ALT predictors were septation thickness (gain ratio merit [GRM] 0.623 ± 0.025, p = 0.0055), intra- and peritumoral STIR signal discrepancy (GRM 0.458 ± 0.046, p < 0.0001), orthogonal diameter (GRM 0.554 ± 0.188, p = 0.0013), contrast enhancement (GRM 0.235 ± 0.015, p = 0.0010) and maximum diameter (GRM 0.221 ± 0.075, p = 0.0009). The quantitative features did not provide a significant discriminatory value. The highest-ranked predictors were used to generate a five-tiered score for the identification of ALTs (correct classification rate 95.7% at a cut-off of three positive items, sensitivity 100.0%, specificity 94.9%, likelihood ratio 19.5). Several single MRI features have a substantial diagnostic value in the identification of ALT, yet a multiparametric approach by a simple combination algorithm may support radiologists in the identification of lipomatous tumors in need for further histological assessment.

Robustness of Radiomic Features: Two-Dimensional versus Three-Dimensional MRI-Based Feature Reproducibility in Lipomatous Soft-Tissue Tumors.

This retrospective study aimed to compare the intra- and inter-observer manual-segmentation variability in the feature reproducibility between two-dimensional (2D) and three-dimensional (3D) magnetic-resonance imaging (MRI)-based radiomic features. The study included patients with lipomatous soft-tissue tumors that were diagnosed with histopathology and underwent MRI scans. Tumor segmentation based on the 2D and 3D MRI images was performed by two observers to assess the intra- and inter-observer variability. In both the 2D and the 3D segmentations, the radiomic features were extracted from the normalized images. Regarding the stability of the features, the intraclass correlation coefficient (ICC) was used to evaluate the intra- and inter-observer segmentation variability. Features with ICC > 0.75 were considered reproducible. The degree of feature robustness was classified as low, moderate, or high. Additionally, we compared the efficacy of 2D and 3D contour-focused segmentation in terms of the effects of the stable feature rate, sensitivity, specificity, and diagnostic accuracy of machine learning on the reproducible features. In total, 93 and 107 features were extracted from the 2D and 3D images, respectively. Only 35 features from the 2D images and 63 features from the 3D images were reproducible. The stable feature rate for the 3D segmentation was more significant than for the 2D segmentation (58.9% vs. 37.6%, p = 0.002). The majority of the features for the 3D segmentation had moderate-to-high robustness, while 40.9% of the features for the 2D segmentation had low robustness. The diagnostic accuracy of the machine-learning model for the 2D segmentation was close to that for the 3D segmentation (88% vs. 90%). In both the 2D and the 3D segmentation, the specificity values were equal to 100%. However, the sensitivity for the 2D segmentation was lower than for the 3D segmentation (75% vs. 83%). For the 2D + 3D radiomic features, the model achieved a diagnostic accuracy of 87% (sensitivity, 100%, and specificity, 80%). Both 2D and 3D MRI-based radiomic features of lipomatous soft-tissue tumors are reproducible. With a higher stable feature rate, 3D contour-focused segmentation should be selected for the feature-extraction process.

The Diagnostic Value of Pathology Examination in Clinically Unsuspected Lipomatous Soft-tissue Tumors

Soft-tissue tumors range from benign to malignant tumors. Although these tumors are frequently unsuspected during surgical excision, additional pathology examination is usually performed in the absence of national guidelines in combination with the fear of missing a malignant tumor. The aim of this study is to investigate if it is safe to refrain from routinely performing pathology examinations of soft-tissue tumors when they are clinically unsuspected to have malignant origins. Data from all routinely performed pathology examinations from patients with one or more clinically unsuspected resected soft-tissue tumors between January 2018 and January 2021 were retrospectively extracted from a merged prospectively maintained institutional database. The primary outcome was the overall rate of premalignant and malignant soft-tissue tumors. Secondary outcomes included specific patient and tumor characteristics in patients with premalignant or malignant soft-tissue tumors and the healthcare costs associated with the performed pathology examinations. In this study, 1,035 resected soft-tissue tumors from 823 patients were analyzed. In total, 1,033 tumors (99.8%) turned out to be benign during the pathology examination, and the remaining two tumors (0.2%) were intermediate soft-tissue tumors without clinical consequences. Both intermediate soft-tissue tumors were larger than 10 cm during clinical examination and were larger than 5 cm during the final pathology examination. The estimated costs spent to perform these pathology examinations were €44,009. Refraining from pathology examination in unsuspected soft-tissue tumors smaller than 5 cm seems to be safe, as no malignant tumor was found in this large cohort of patients. In addition, a cost reduction of €11,000 per year can be achieved by refraining from pathology examinations in this specific group of small non-suspected soft-tissue tumors.

MRI-based radiomics to predict lipomatous soft tissue tumors malignancy: a pilot study

ObjectivesTo develop and validate a MRI-based radiomic method to predict malignancies in lipomatous soft tissue tumors.MethodsThis retrospective study searched in the database of our pathology department, data from patients with lipomatous soft tissue tumors, with histology and gadolinium-contrast enhanced T1w MR images, obtained from 56 centers with non-uniform protocols. For each tumor, 87 radiomic features were extracted by two independent observers to evaluate the inter-observer reproducibility. A reduction of learning base dimension was performed from reproducibility and relevancy criteria. A model was subsequently prototyped using a linear support vector machine to predict malignant lesions.ResultsEighty-one subjects with lipomatous soft tissue tumors including 40 lipomas and 41 atypical lipomatous tumors or well-differentiated liposarcomas with fat-suppressed T1w contrast enhanced MR images available were retrospectively enrolled. Based on a Pearson’s correlation coefficient threshold at 0.8, 55 out of 87 (63.2%) radiomic features were considered reproducible. Further introduction of relevancy finally selected 35 radiomic features to be integrated in the model. To predict malignant tumors, model diagnostic performances were as follow: AUROC = 0.96; sensitivity = 100%; specificity = 90%; positive predictive value = 90.9%; negative predictive value = 100% and overall accuracy = 95.0%.ConclusionThis work demonstrates that radiomics allows to predict malignancy in soft tissue lipomatous tumors with routinely used MR acquisition in clinical oncology. These encouraging results need to be further confirmed in an external validation population.

Lipomatous Soft-tissue Tumors.

Lipomatous soft-tissue tumors are the most common neoplasms encountered by physicians. They range from benign lipomas to high-grade liposarcomas. Unplanned excisions of sarcomas are commonly due to the presumptive diagnosis of lipoma and can be avoided by understanding their diagnostic magnetic resonance imaging appearance. Magnetic resonance images should be obtained for all soft-tissue masses that are deep to fascia or those >5 cm in subcutaneous tissue. Atypical lipomatous tumors present as large deep fatty masses and have a propensity for local recurrence and a small risk of malignant transformation. Well-differentiated liposarcomas are histologically identical to atypical lipomatous tumors but have a markedly worse prognosis secondary to their anatomic location. Masses that lack isointense signal to subcutaneous fat on MRI may represent a sarcoma and require a biopsy before definitive treatment. Large deep lipomatous masses and liposarcomas should be sent to a sarcoma referral center for definitive treatment.

Magnetic Resonance Imaging Assessment of Lipomatous Soft-tissue Tumors.

To establish the accuracy of magnetic resonance imaging (MRI) in distinguishing between benign and malignant lipomatous tumors; to evaluate the reproducibility of the MRI interpretation assessing the agreement between judgments of two radiologists with the same experience in soft-tissue sarcomas; to identify an association among MRI findings (size, depth, septa, nodules, signal homogeneity) and nature of the lesion. A total of 54 patients (28 men and 26 women), with a mean age of 56 (range=27-84) were included years. All subjects followed-up by the Multidisciplinary Sarcoma Group. The following MRI findings were judged in a blind study by two radiologists: size, localization, septa, nodules and signal homogeneity. A diagnostic indication was then given from among lipoma, atypical lipomatous tumour (ALT) and liposarcoma. Accuracy in distinguishing between benign and malignant lesions, and between lipoma and ALT (Fisher's exact test), inter-operator agreement (Cohen's kappa), association of MRI findings and malignancy of the lesion (Fisher's exact test and odds ratio) were evaluated. The inter-operator agreement was complete (100%). The agreement between diagnostic hypothesis and histological diagnosis was statistically significant (p<0.05). Among the radiological findings taken into account, only septa and signal homogeneity were significantly associated with the malignancy of the lesion (p<0.05). MRI could be helpful in distinguishing lipomatous tumors, allowing biopsy to be avoided in some cases (negative predictive value=100%).

Myolipoma of Mesentery: A Case Report

Myolipomas are very rare benign lipomatous soft tissue tumors which are usually located in retroperitoneum, abdominal and pelvic cavity, and the abdominal wall. They can be diagnosed histologically by the presence of irregularly admixed mature adipose tissue and smooth muscle fibers. The correct diagnosis of myolipoma is important, because it should be considered in the differential diagnosis of fat-containing lesions of the soft tissue and should follow a benign clinical course despite its frequently large size and deep location. We report here a case of myolipoma arising in the mesentery of the jejunum.

A comparison between histopathology and findings on magnetic resonance imaging of subcutaneous lipomatous soft-tissue tumors

ObjectiveTo retrospectively analyse the magnetic resonance (MR) findings of subcutaneous lipomatous soft-tissue tumours (SLSTT) in order to define a diagnostic and therapeutic strategy.MethodsThe MR findings of 46 SLSTT were registered for the following data: area, location within the subcutaneous compartment, dimensions, shape and delineation, signal intensity (SI) on different pulse sequences, signal homogeneity, degree and pattern of contrast enhancement. The MR findings, together with patients' age and gender, were compared with histopathological findings.ResultsSixty-eight percent of the lipomas had a homogeneous T1-SI identical to the SI of subcutaneous fat. Heterogeneity in other lipomas was due to fat necrosis and small septa. Other lesions with homogeneous T1-SI identical to the SI of subcutaneous fat included lipoblastoma, lipomatosis and lipoma-like hibernoma. None of the liposarcomas were homogeneous and isointense to SI of subcutaneous fat on T1-weighted imaging (WI). Lipoma variants and liposarcomas showed overlapping MR characteristics.ConclusionsSLSTT with homogeneous T1-SI identical to the SI of subcutaneous fat are benign. If a SLSTT has other MR characteristics, differentiation based on MRI cannot be made and biopsy is needed. We used this finding in defining a diagnostic and therapeutic strategy for subcutaneous soft tissue tumours that are hyperintense on T1-WI.

Interscapular hibernoma—Case report and literature review

Hibernoma is a rare benign tumor that arises from the vestiges of fetal brown fat. We present a case of interscapular hibernoma. Computed tomography scan showed a well-circumscribed, hypodense mass with peripheral enhancement, and magnetic resonance imaging revealed intermediate high T1 and T2 signal intensities with incomplete fat suppression. Although it is rare, hibernoma should be included in the differential diagnosis of lipomatous soft-tissue tumors. This is a benign tumor with no malignant potential. Complete excision is the treatment choice.

Significance of LRP and PPAR-γ Expression in Lipomatous Soft Tissue Tumors

Background:Molecular mechanism of differentiation in lipogenic tumor is still unknown in detail. Low-density lipoprotein receptor-related protein (LRP) and peroxisome proliferator-activated receptor gamma (PPAR-γ), representative regulatory molecules of lipogenic differentiation, have been reported today as multi-functional molecules and to modulate tumorigenesis in various kind of cancer. To date, diagnostic and therapeutic significance of the expression of these molecules in lipogenic tumors are not defined. Methods:The immunohistochemical expression status of LRP and PPAR-γ in various grades of 54 lipogenic tumors was analyzed. Correlation between the expression levels and the differentiation of the tumors was confirmed. For statistical analyses, the Kruskal-Wallis test, the Steel-Dwass test and the Mann–Whitney U test were used. Results:LRP and PPAR-γ expression was detected in 50 (92.6%) and 44 (81.5%) cases, respectively. The expression level in LRP was significantly higher in cases with well differentiated liposarcoma, pleomorphic liposarcoma and dedifferentiated liposarcoma than in lipoma. Compared with lipoma or well differentiated liposarcoma, significant elevation in expression level of PPAR-γ was confirmed in myxoid liposarcoma, pleomorphic liposarcoma, dedifferentiated liposarcoma and the differentiated area of dedifferentiated liposarcoma. Conclusion:The up-regulation of LRP and PPAR-γ in higher grade cases, i.e. less differentiated tumors than in low grade cases was shown, suggesting the candidate role of these molecules as tumor progression modulators rather than regulatory molecules of differentiation in lipogenic tumors.

Sonographic findings of hibernoma. A report of two cases

We present 2 cases of hibernoma, a rare lipomatous tumor arising from brown fat tissue. In each case, a hyperechoic mass in comparison to surrounding musculature combined with elevated vascularization was highly suggestive of a liposarcoma. As a rule, malignancy cannot be excluded safely by imaging modalities, and a preoperative biopsy should be performed. Although rare, hibernomas should be considered in the differential diagnosis of lipomatous soft-tissue tumors.

Differential expression of leptin in lipomatous and non-lipomotaous soft tissue tumors

Differential expression of leptin in lipomatous and non-lipomotaous soft tissue tumors

Histologic Correlation With Magnetic Resonance Imaging for Benign and Malignant Lipomatous Masses

Purpose/results. We evaluated the diagnostic accuracy of magnetic resonance imaging (MRI) for 46 consecutive patients with lipomatous soft tissue tumors prior to biopsy and resection. Twenty-eight patients had benign lipomas and 18 had liposarcomas. Clinical differences between thdse patients with benign disease and those with malignant lesions were average age at the time of presentation (49 years for benign vs 62 years for malignant, p < 0.001) and average length of symptoms prior to resection (64 months for benign versus 38 months for malignant, p = 0.01). MRI characteristics associated with benign disease included: smaller tumor size (9.4 cm average greatest dimension for benign lesions vs 13.4 cm for malignant masses, p = 0.022); a mass with a uniformly homogeneous signal (p = 0.0003); a mass with homogeneous high T1 and T2 signals and a low short-time-inversion-recovery (STIR) signal comparable to normal fat (p < 0.0001). This last signal pattern was not seen in malignant lesions (0/18) and was present in almost all benign lipomas (25/28). The usual MRI descriptions of soft tissue masses such as infiltrating vs encapsulating, deep vs subcutaneous and septated vs non-septated were not helpful predictors of malignancy in this series. Needle biopsies of lipomatous masses with heterogeneous signals on MRI resulted in inaccurate diagnoses due to sampling error in 5/9 patients. Discussion. A carefully planned and performed MRI study of lipomatous masses can accurately predict a benign lipoma whenever a homogeneous high T1 and T2, as well as a low STIR, signal is present. However, a mass with any other signal characteristics must be biopsied carefully in order to make an accurate diagnosis.

Evaluation of Lipomatous Soft Tissue Tumors by MR Imaging

Evaluation of Lipomatous Soft Tissue Tumors by MR Imaging

Evaluation of Lipomatous Soft Tissue Tumors by MR Imaging

Large soft tissue tumors — 5 cm or greater — or deep-seated tumors have a greater risk of being malignant than smaller and superficially located tumors (9). In a period of 2 years 43 consecutive patients with lipomatous tumors 5 cm in diameter or greater were examined with MR imaging. The MR findings were correlated to histologic features and diagnosis. Twenty-six tumors were classic lipomas both on MR and at microscopy; 8 lipomas showed other features — some of them raising suspicion of malignancy at MR; all, however, were histologically benign. Nine tumors were considered malignant at MR imaging; all 9 proved to be malignant by microscopy.

Evaluation of Lipomatous Soft Tissue Tumors by MR Imaging

Large soft tissue tumors--5 cm or greater--or deep-seated tumors have a greater risk of being malignant than smaller and superficially located tumors (9). In a period of 2 years 43 consecutive patients with lipomatous tumors 5 cm in diameter or greater were examined with MR imaging. The MR findings were correlated to histologic features and diagnosis. Twenty-six tumors were classic lipomas both on MR and at microscopy; 8 lipomas showed other features--some of them raising suspicion of malignancy at MR; all, however, were histologically benign. Nine tumors were considered malignant at MR imaging; all 9 proved to be malignant by microscopy.