Although myxoid liposarcoma is a subtype of liposarcoma, it may be difficult to establish the correct diagnosis with magnetic resonance (MR) imaging due to the lack of fat signal intensity. Without the administration of gadolinium contrast material, the tumor may even mimic a cystic tumor. A spectrum of MR imaging abnormalities occur in myxoid liposarcoma, depending on the amount of fat and myxoid material, the degree of cellularity and vascularity, and the presence of necrosis. Most myxoid liposarcomas have lacy or linear, amorphous foci of fat. Some myxoid liposarcomas appear to be cystic at nonenhanced MR imaging, although they enhance like other solid masses at contrast material-enhanced MR imaging. The enhancing areas within the tumor represent increased cellularity and vascularity; the nonenhancing areas represent necrosis, reduced cellularity, and accumulated mucinous material. Gadolinium-enhanced imaging is important in differentiating myxoid liposarcoma from benign cystic tumors. Characterization of the tumor with MR imaging plays an important role in the management of myxoid liposarcoma.

MRI shows features helpful for differentiating extraaxial neurofibromas from neurilemmomas; however, no single finding or combination of findings allows definitive differentiation.

Pilomatricoma should be considered when US or CT shows a well-defined hyperechoic or calcific nodule in subcutaneous fat attached to the skin in children. MR images may be helpful in diagnosis. Pathologic findings are well correlated with imaging findings.

Neoplasms and tumorlike lesions that originate from chest wall tissues are uncommon compared with tumors in other parts of the body, and unfamiliarity with these disease entities can cause diagnostic difficulties for radiologists. Furthermore, the imaging features of many of these tumors are nonspecific, particularly those that are locally aggressive. However, a systematic approach based on patient age, clinical history, lesion location, and characteristic imaging findings often helps limit the differential diagnosis. Primary chest wall tumors can be classified as bone or soft-tissue tumors, with the latter being further classified into adipocytic tumors, vascular tumors, peripheral nerve sheath tumors, cutaneous lesions, fibroblastic-myofibroblastic tumors, and so-called fibrohistiocytic tumors, largely based on the 2002 World Health Organization classification. Within each category, it is possible to further limit the differential diagnosis with cross-sectional imaging. Information on specific features (eg, mineralization, fibrosis, hemosiderin deposits) and imaging patterns (eg, the "target sign" and "fascicular sign" seen in neurogenic tumors) can aid in making the diagnosis. Radiologists can achieve a sufficiently specific diagnosis of bone tumors and soft-tissue tumors if typical findings are present.

Abbreviations: GSPE, grape seed proanthocyanidin extract; MIA, monosodium iodoacetate; MMP, matrix metalloproteinase; O2 -, superoxide anion; OA, osteoarthritis; OH, hydroxyl radicals; ONOO -, peroxynitrite; PWL, paw withdrawal latency; PWT, paw withdrawal threshold; ROS, reactive oxygen species; TRP, transient receptor potential; VIP, vasoactive intestinal peptide Abstract Osteoarthritis (OA) is an age-related joint disease that is characterized by degeneration of articular cartilage and chronic pain. Oxidative stress is considered one of the pathophysiological factors in the progression of OA. We investigated the effects of grape seed proanthocyanidin extract (GSPE), which is an antioxidant, on monosodium iodoacetate (MIA)-induced arthritis of the knee joint of rat, which is an animal model of human OA. GSPE (100 mg/kg or 300 mg/kg) or saline was given orally three times per week for 4 weeks after the MIA injection. Pain was measured using the paw withdrawal latency (PWL), the paw withdrawal threshold (PWT) and the hind limb weight bearing ability. Joint damage was assessed using histological and microscopic analysis and microcomputerized tomography. Matrix metalloproteinase-13 (MMP13) and nitrotyrosine were detected using immunohistochemistry. Administration of GSPE to the MIA-treated rats significantly increased the PWL and PWT and this resulted in recovery of hind paw weight distribution (P ＜ 0.05). GSPE reduced the loss of chondrocytes and proteoglycan, the production of MMP13, nitrotyrosine and IL-1β and the formation of osteophytes, and it reduced the number of subchondral bone fractures in the MIA-treated rats. These results indicate that GSPE is antinociceptive and it is protective against joint damage in the MIA-treated rat model of OA. GSPE could open up novel avenues for the treatment of OA.

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The five patients with brown tumor demonstrated a wide spectrum of MR imaging findings. There are few lesions that are osteolytic on the radiographs and that show a short T2 on MR imaging, such as brown tumor. Multiple cystic or mixed lesions are the expected findings of brown tumors.

If a sonogram reveals an oval mass in the subcutaneous tissue that is abutting against the skin and has a focal lobulated margin with hypoechogenicity or an irregular margin with mixed echogenicity, a diagnosis of DP should be considered.