After reviewing each patient MRI on a PACS viewing module, observers indicated whether the amount of stranding, nodularity, and size of each tumor was concerning for well-differentiated liposarcoma and rendered a diagnosis of lipoma or well-differentiated liposarcoma.
To simulate a clinical scenario, each reader was given the ability to use whatever image sequences available for diagnostic purposes see later. Stranding Figure 3 was defined as linear tissue heterogeneity present within the mass, and nodularity Figure 4 was defined as intralesional tissue heterogeneity that was not linear.
As the variables of size, stranding, and nodularity are used clinically by radiologists without standardization criteria to interpret such images and render a diagnosis, these variables were intentionally not standardized for individual readers for the purpose of this study. This was done to simulate a clinical scenario and therefore better evaluate the ability of readers to render a correct diagnosis and to determine the reliability and validity of reader diagnoses towards these tumors.
All imaging was performed with 1. In all of the cases reviewed, either T2W fast spin echo imaging with spectral fat suppression or STIR imaging was performed. Imaging sequences used by readers of this study for diagnostic purposes were performed without contrast agents.
The interobserver reliability was evaluated by determining the agreement among the observers. All values were two-sided and any -values less than 0.
Data analysis was performed using SAS version 9. All readers chose liposarcoma more frequently than lipoma. Table 1 shows the interrater reliability for diagnosis and each of the categorical variables of stranding, nodularity, and size.
Tables 2 and 3 show the relationships of stranding, nodularity, and size to the diagnosis of liposarcoma. Positive reader responses for stranding and nodularity were associated with an increased likelihood of liposarcoma diagnosis.
Although this combination had a higher probability of a true liposarcoma diagnosis, readers overdiagnosed liposarcoma by a large margin in this instance. There was no difference regarding interpretation of these categorical variables or their relationship towards the ultimate diagnosis when compared between specialties.
Well-differentiated liposarcomas do however represent a diagnostic dilemma given the difficulty discerning well-differentiated liposarcoma from lipoma on imaging and problems associated with sampling error during biopsy [ 2 ]. As such, a standardized approach to the radiographic evaluation and treatment of these lesions would be beneficial to both patients and the physicians who care for them.
The goal of this study was to determine whether experienced observers in musculoskeletal radiology and orthopaedic oncology could differentiate between lipomas and well-differentiated liposarcomas on imaging alone and to determine the relative association of variables such as stranding, nodularity, and size to this diagnosis. Our hypothesis was that even experienced observers would be unable to differentiate between lipomas and well-differentiated liposarcomas.
Therefore, if treating physicians were unable to accurately diagnose these tumors on imaging or via biopsy, an argument suggesting that all symptomatic low-grade fatty lesions may be treated with marginal excision could be supported. While the results presented here are better than chance alone, they do reaffirm that a definitive diagnosis cannot be made on imaging alone until better imaging criteria are identified.
We also present data here that supports several other variables surrounding the radiographic diagnosis of low-grade fatty lesions. First, there is a substantial interrater reliability based on kappa statistics towards making the radiographic diagnosis. Finally, the variables of size, nodularity, and stranding did show an association with the diagnosis of well-differentiated liposarcoma and as such based on these data should continue to be used in the radiographic interpretation of these tumors.
Other authors have evaluated the utility of MRI in the differentiation of well-differentiated liposarcoma from lipoma and determined the value of fluid-sensitive imaging sequences in making this distinction [ 2 , 3 , 10 ].
Doyle et al. This study however only had two observers, both radiologists, and a small representative number of well-differentiated liposarcomas in the study design 18 of 51 tumors.
In addition, these authors attempted to correlate the radiographic findings with pathological variables like fibrosis, stranding, and nodularity; however, they were unable to make associations between these pathological variables and the observed radiographic parameters.
As such, Doyle et al. Our data however suggests that the variables of nodularity, stranding, and size do show association with the correct radiographic diagnosis and therefore should continue to be used despite the poor correlation to pathological variables. One key point in the differentiation between the presented data and that of Doyle et al. In one such report, Gaskin and Helms retrospectively reviewed lesions and determined the sensitivity, specificity, and accuracy of MRI in making the distinction between lipoma, lipoma variants, and well-differentiated liposarcoma [ 10 ].
Only after selection of cases which other radiologists had been confident enough to use such terms were the pathological diagnoses reviewed. Given the heterogeneity of fatty tumors and the fact that the pathological diagnosis is the most valid, our presented accuracy may be appropriate. The second difference between the study by Gaskin and Helms was that only 64 of tumors were resected at their tertiary institution and available for review by their trained musculoskeletal pathologist.
Again, given the heterogeneity within the diagnosis of well-differentiated liposarcoma and the specific diagnostic criteria surrounding this diagnosis, the presented radiological accuracy in that study may not be truly representative of all low-grade fatty lesions [ 9 ].
Data presented here suggests that the variables of size, nodularity, and stranding show an association with the ultimate pathological diagnosis and as such should continue to be used in the radiographic interpretation [ 2 ]. It has been our experience that size is the variable most often used by referral centers or radiologists to suggest a diagnosis of well-differentiated liposarcoma but the variable least used by our treatment team in making the ultimate decision a MRI diagnosis.
Obviously size does matter given the association between concerning size and the pathological diagnosis of well-differentiated liposarcoma [ 2 ].
While the association of size to the diagnosis of well-differentiated liposarcoma was not as strong as the variables of stranding and nodularity Figures 3 and 4 , all these represent variables that need to be considered when rendering an ultimate radiographic impression.
Recently, the identification and gene amplification of the MDM2 gene have been identified to supplement the pathological diagnosis of liposarcoma [ 14 , 15 ]. For the majority of patients in this study, the pathological analysis and diagnosis were made without usage of MDM2 gene amplification. This represents a limitation to this study. For this study, pathological review and diagnosis were made by one of three pathologists with subspeciality training in musculoskeletal oncology and sarcoma pathology following WHO criteria for the classification of sarcoma.
At tertiary referral sarcoma centers, where the treatment team understands the low metastatic potential of these lesions and the appropriateness of a marginal excision, the inability to differentiate these lesions on MRI alone does not represent a major treatment dilemma, as symptomatic tumors require marginal excision without adjuvant treatment [ 5 , 6 , 16 ]. Phrases such as these lead to patient worry and unnecessary referral. Then, with an understanding of the low metastatic risk and appropriate management of these tumors, treating physicians could more appropriately counsel patients and avoid unnecessary referral.
This level of accuracy needs to be improved upon with accepted and validated mechanisms to differentiate between these two entities.
The variables of nodularity, stranding, and relative size do show an association with the diagnosis of well-differentiated liposarcoma and therefore should continue to be used in the radiographic impression. The authors would like to thank the participant readers involved in data collection for this study: Drs. This study could not have been conducted without their involvement. If untreated, they can spread throughout the body. There may be no other symptoms other than being able to feel a lump in an area of fatty tissue.
As the tumor grows, symptoms can include:. Liposarcoma begins when genetic changes occur in fat cells, causing them to grow out of control. In the United States, there are about 2, new cases of liposarcoma a year. It seldom affects children. The diagnosis can be made with a biopsy. A sample of tissue will need to be removed from the tumor.
If the tumor is hard to reach, imaging tests such as an MRI or CT scan can be used to guide the needle to the tumor. Imaging tests can also help determine the size and number of tumors. These tests can also tell if nearby organs and tissues have been affected.
The tissue sample will be sent to a pathologist, who will examine it under a microscope. The pathology report will be sent to your doctor. This report will tell your doctor whether the mass is cancerous, as well as details about the type of cancer. The main treatment is surgery. The goal of surgery is to remove the entire tumor plus a small margin of healthy tissue. This may not be possible if the tumor has grown into vital structures.
Radiation is a targeted therapy that uses energy beams to kill cancer cells. It can be used after surgery to destroy any cancer cells that may have been left behind. Chemotherapy is a systemic treatment involving powerful drugs to kill cancer cells. Following surgery, it can be used to destroy cancer cells that may have broken off from the primary tumor.
Clinical trials may be an option as well. Ask your doctor about clinical trials that may be a good fit for you. Liposarcoma can be successfully treated. Your prognosis depends on many individual factors, such as the:. According to the Liddy Shriver Liposarcoma Initiative , surgery combined with radiation therapy has been shown to prevent recurrence at the surgical site in 85 to 90 percent of cases.
Some features of a lipoma include:. Most lipomas are symptomless, but some are painful when applying pressure. A lipoma that is tender or painful is usually an angiolipoma. This means the lipoma has an increased number of small blood vessels. Painful lipomas are also a feature of adiposis dolorosa or Dercum disease. Diagnosis of lipoma is usually made clinically by finding a soft lump under the skin.
However, if there is any doubt, a deep skin biopsy can be performed which will show typical histopathological features of lipoma and its variants, such as a hibernoma. The rare fatty cancer , liposarcoma, almost never arises in the skin. Liposarcoma is a deep-seated tumour, and most often grows on thigh, groin or at the back of the abdomen. If your lipoma is enlarging or becomes painful, check with your doctor.
A skin biopsy may be required to exclude liposarcoma. Most lipomas require no treatment. They eventually stop growing and persist without causing any problems. Occasionally, a lipoma that interferes with the movement of adjacent muscles may require surgical removal.
Several methods are available:.
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