From the archives of the AFIP: Benign musculoskeletal lipomatous lesions

Department of Radiologic Pathology, Armed Forces Institute of Pathology, 6825 16th St NW, Bldg 54, Rm M-133A, Washington, DC 20306, USA.
Radiographics (Impact Factor: 2.73). 01/2004; 24(5):1433-66. DOI: 10.1148/rg.245045120
Source: PubMed

ABSTRACT Benign lipomatous lesions involving soft tissue are common musculoskeletal masses that are classified into nine distinct diagnoses: lipoma, lipomatosis, lipomatosis of nerve, lipoblastoma or lipoblastomatosis, angiolipoma, myolipoma of soft tissue, chondroid lipoma, spindle cell lipoma and pleomorphic lipoma, and hibernoma. Soft-tissue lipoma accounts for almost 50% of all soft-tissue tumors. Radiologic evaluation is diagnostic in up to 71% of cases. These lesions are identical to subcutaneous fat on computed tomographic (CT) and magnetic resonance (MR) images and may contain thin septa. Lipomatosis represents a diffuse overgrowth of mature fat affecting either subcutaneous tissue, muscle or nerve, and imaging is needed to evaluate lesion extent. Lipoblastoma is a tumor of immature fat occurring in young children, and imaging features may reveal a mixture of fat and nonadipose tissue. Angiolipoma, myolipoma, and chondroid lipoma are rare lipomatous lesions that are infrequently imaged. Spindle cell and pleomorphic lipoma appear as a subcutaneous lipomatous mass in the posterior neck or shoulder, with frequent nonadipose components. Hibernoma appears as a lipomatous mass with serpentine vascular elements. Benign lipomatous lesions affecting bone, joint, or tendon sheath include intraosseous lipoma, parosteal lipoma, liposclerosing myxofibrous tumor, discrete lipoma of joint or tendon sheath, and lipoma arborescens. Intraosseous and parosteal lipoma have a pathognomonic CT or MR appearance, with fat in the marrow space or on the bone surface, respectively. Liposclerosing myxofibrous tumor is a rare intermixed histologic lesion commonly located in the medullary canal of the intertrochanteric femur. Benign lipomatous lesions may occur focally in a joint or tendon sheath or with diffuse villonodular proliferation in the synovium (lipoma arborescens) and are diagnosed based on location and identification of fat. Understanding the spectrum of appearances of the various benign musculoskeletal lipomatous lesions improves radiologic assessment and is vital for optimal patient management.

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    ABSTRACT: Intraosseous lipoma is a rare benign tumor, mostly occurring in lower limb especially in os calcis and the metaphyses of long bones. Intraosseous lipoma of the skull is even rarer, with 12 cases having been reported to involve the sphenoid bone in the literature. We present the third reported case of sphenoclival intraosseous lipoma in a 43-year-old man with headache, hyperprolactinemia and visual disturbance. Performed Magnetic Resonance Imaging (MRI) revealed pituitary macroadenoma as well as a mildly expansile lesion with high signal intensity on both T1- and T2-weighted sequences within the left greater wing of the sphenoid and the clivus. The patient refused to undergo surgical removal of pituitary macroadenoma and medical treatment was initiated instead; thereafter, follow up Computed Tomography (CT) and MRI scans revealed regression of the pituitary macroadenoma whereas the sphenoclival lesion was depicted as a welldefined fat-containing intraosseous lesion which showed no perceptible growth, 17 months later.
    The Open Neuroimaging Journal 11/2012; 6:99-102. DOI:10.2174/1874440001206010099
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    ABSTRACT: This is an interesting paper of a 4 cm posttraumatic pseudolipoma on the back of the neck of an adult man who has participated in "tar barrel rolling" since adolescence. To the best of our knowledge, this is the first case of a pseudolipoma to be reported in the literature in association with tar barreling.
    08/2012; 2012:130973. DOI:10.1155/2012/130973
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    ABSTRACT: BackgroundThe purpose of this study is to determine if giant size is of bad prognosis in deep lipomas of the upper extremity.Patients and methodsWe report a retrospective study of 13 patients with deep-seated lipomas of the upper extremity treated during the period from April 1997 to April 2008. We evaluated the clinical and radiological characteristics, treatment and evolution profile of these patients.ResultsThere were 10 women and three men, with an average age of 53 years (range 30–79 years). Seven of these lipomas were in the arm, one in the shoulder, and five in the forearm. Six lipomas were intramuscular, six intermuscular (three of them being attached to bone and labelled parosteal lipoma) and one epivaginal lipoma of the flexor tendon sheath. All patients presented a progressive slow-growing mass that was associated with radial paralysis in one case and carpal tunnel syndrome in one case. Plain radiographs showed a radiolucent soft-tissue image in all cases and an associated osteochondroma in one parosteal lipoma. Computer tomography (CT) or magnetic resonance imaging (MRI) suggested the lipomatous nature and benign characteristics of these deep lipomas that were giant in all cases (mean size: 7 cm). Lipoma marginal excision was performed and histopathological examination demonstrated features consistent with a benign lipoma. There was good function and no clinical recurrence was observed after a mean follow-up of three years.DiscussionGiant deep-seated lipomas of the upper extremity are uncommon and can be intermuscular or intramuscular. A painless soft-tissue mass is the most frequent chief complaint. MRI with fat suppression suggests the diagnosis and studies the extension of deep lipoma. Marginal excision is the treatment of choice and histopathology eliminates diagnosis of well-differentiated liposarcoma.ConclusionAppropriate evaluation of deep lipoma is to rule out malignancy by systematically performing MRI and biopsy. In contrast to deep-seated lipomas of the lower extremity or the retroperitoneal space, the prognosis of deep-seated lipomas of the upper extremity is good irrelevant of their size. Recurrence and the degeneration are very rare.Level of evidenceLevel 4.
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