A Case of Pilomatricoma in the Upper Arm: Sonographic and MR Imaging Findings

Pilomatricoma is an uncommon benign skin neoplasm arising from the hair matrix. The radiologic features of this uncommon tumor have occasionally been described in the literature however, to the best of our knowledge, there have been no reports in Korea on the sonographic and MR imaging findings of pilomatricoma involving the upper arm. In this article, we describe the imaging findings of a case of pilomatricoma involving the upper arm, with the emphasis being placed on the sonographic and MR imaging findings and a review of the literature.

Extraskeletal Ewing Sarcoma of Cervical Epidural Region: Cases Report

Extraskeletal Ewing sarcoma is a rare malignant tumor found in children and young adults. It commonly occurs in deep soft tissue of the trunk, especially in the paravertebral region and extremities. We report two cases of extraskeletal Ewing sarcoma occurring as a cervical epidural tumor in elderly patients. The MRI and CT findings showed that paravertebral epidural tumors had invaded the spinal canal through the intervertebral foramen. At T1-weighted MR imaging, the masses were isointense to muscle, and at T2* and T2-weighted images were hyperintense, and heterogeneous contrast enhancement was observed. Extraskeletal Ewing sarcoma, though quite rare, should be borne in mind in the differential diagnosis of paraspinal epidural tumors.

Dedifferentiated Liposarcoma in the Thigh: Case Report

Dedifferentiated liposarcoma occurs in less than 10% of all liposarcoma and is found most often in the retroperitoneum and extremities. Histologically, the tumor was composed of well-defferentiated liposarcomastous areas with malignant fibrous histiocytoma-like area, peculiar neurallike whirling pattern associated and focal metaplastic bone formation. The rare radiologic feature of this have not been sufficiently described in the previous literature, and we now report a case of dedifferentiated liposarcoma in the thigh.

Inflammatory Myofibroblastic Tumor of Perineal Soft Tissue: A Case Report

Inflammatory myofibroblastic tumor is a rare benign condition of unknown etiology, and it may simulate malignancy. It is composed of myofibroblast, plasma cells and histiocytes and is found in lung, the liver, orbit, skin, mesentery, retroperitoneum and maxillary sinus. We report a case of inflammatory myofibroblastic tumor of perineal subcutaneous fat in a 35-year-old woman who complained of a palpable mass. Ultrasonography revealed a well-marginated lobulated hypoechoic lesion with peripheral poorly-defined hyperechoic strands in the subcutaneous fat of the right perineum. The lesion demonstrated low signal intensity on T1-weighted images and of heterogenous high signal intensity on T2-weighted images, compared with surrounding muscle. After intravenous injection of gadolinium, it showed clear homogeneous enhancement but poorlydefined adjacent strands. The final histologic diagnosis was inflammatory myofibroblastic tumor.

MR Imaging of Soft-Tissue Vascular Lesions: Pathologic Correlation

In the evaluation of vascular lesions, MR can be used to distinguish slow- from high-flow lesions on the basis of the observed spin-echo MR signal characteristics. MR imaging can also represent features of the static tissues of the vascular lesions that are composed of fibrofatty components, as well as thromboses, phleboliths and muscle atrophy. This paper illustrates the MR findings of various vascular lesions, correlating them with the pathologic specimen and emphasizing on the static tissues.

Liposarcoma: MR Findings in the Histologic Subtypes

PURPOSE: To evaluate the MR imaging findings of liposarcomas of different histologic subtypes. MATERIALS AND METHODS: We evaluated MR images of 21 patients (5 men and 16 women, mean age, 55 years) with liposarcoma andcorrelated the findings with the results of histopathology. In the study group seven liposarcomas werewell-differentiated, seven were myxoid, three were mixed, two were pleomorphic, and one was round cell. RESULTS: On T1 -and T2 - weighted images, six of seven well-differentiated liposarcomas showed signal intensity equal tothe fat and hypointense septa, while the other showed low signal intensity on a T1 -weighted image, heterogeneoushigh signal intensity on a T2- weighted image, heterogeneous enhancement after the administration of contrastmedia and was dedifferentiate. Nine masses in seven patients with myxoid liposarcoma showed low signal intensityon T1-weighted images, six of the nine showed lace-like foci of high signal intensity. On T2 -weighted images, allmasses showed homogeneous high signal intensity. After administration of contrast media, five of seven massesshowed heterogeneous enhancement. Two of three mixed form were well-differentiated and myxoid types, and twosubtypes were separable on MR. Pleomorphic, round cell, mixed type myxoid and pleomorphic and unclassified casesshowed low signal intensity on T1-weighted images, heterogeneous high signal intensity on T2-weighted andheterogeneous enhancement. CONCLUSION: Using MR imaging, well-differentiated and myxoid liposcarcomas may bedifferentiated from other types.

MRI of Ganglion Cysts in Uncommon Sites or with Atypical Appearance

Ganglion cysts are common lesions which are most often found around the hands and feet. Magnetic resonance (MR) imaging is seldom performed; cysts are identified incidentally on MR images obtained for the purpose of evaluating other disorders. Clinically complicated ganglions are often confused with other more serious tumors, and MR examination is thus requested. Ganglions arising from uncommon sites or showing unusual MR findings can lead to wrong diagnosis. Thus, a thorough knowledge of potential sites and of the MR findings of unusual ganglion cysts can prevent mistake s. We therefore describe the MR findings of unusual ganglion cysts, including complicated ganglions, cruciate ligament ganglion cysts, meniscal cysts, labral cysts, ganglions in shoulder notches and tarsal tunnels, and intermuscular ganglion cysts.

MR Findings of Angiomyoma of the Extremities: Two Cases Report

Angiomyoma is a benign soft tissue tumor that arises from the smooth muscle layer of blood vessels in the deeplayers of the dermis, or in subcutaneous tissue. It occurs as a well-encapsulated solitary mass, most of which areless than 2cm in diameter. Some patients complain of pain with or without tenderness. This tumor has apredilection for the lower extremities of middle-aged females. MRI findings of angiomyoma of the extremities haverarely been reported, and we describe these findings in two cases of angiomyoma of the hand and foot.

Ultrasonographic and MR Findings of Cysticercosis in Soft Tissue: A Case Report

We describe an unusual case of cysticercosis in soft tissue. On US, a well-defined oval shaped cystic lesionwith an inner central hyperechoic portion was noted. This portion showed high signal intensity on T1-weightedimages and equivocal enhancement. On MRI, other portions of the lesion showed their cystic nature. Pathologicexamination confirmed the presence of cysticercosis and, in particular, the central portion was found to be amural nodule with scolex. Cysticercosis in the soft tissue and musculature of patients from endemic areas shouldthus be considered in the differential diagnosis of an incidental mass, especially when this is cystic and has aninner central nodule.

MR Findings of Extraabdominal Fibromatosis

PURPOSE: To evaluate the MR findings of extra-abdominal fibromatosis and the role of MRI in primary diagnosis MATERIALS AND METHODS: Fifteen cases in of histologically proven extra-abdominal fibromatosis in 13 patients were retrospectively reviewed. T1-weighted and T2-weighted images were obtained in axial, coronal and sagittal planes. Gd-enhancement was performed in 14 cases, and dynamic enhancement studies in two. All lesions were evaluated for mass shape and margin definition. RESULTS: Among the 15 cases, tumors of the buttock accounted for five, and tumor of the thigh for two. In eight cases tumors were intermuscular and in six cases were intramuscular. In ten cases (67 %) the mass extended along the long axis of the body and in 14 of 15 cases (93%) focal infiltration of adjacent structures was visible. The signal intensity of the lesion was in all cases inhomogeneous on both T1 and T2 weighted images. As seen on Gd-DTPA enhanced scans, the masses were inhomogeneously enhanced. In all cases MRI revealed star-shaped linear strands or a band-like low signal area in the mass. These features were not enhanced and were arranged along the long axis of the mass. CONCLUSION: MR findings of extra-abdominal fibromatosis were relatively characteristic and helpful for primary diagnosis of the condition.

MR Imaging of Masticator Space Infection

PURPOSE: To identify the characteristic appearances of masticator space infection, as seen on magneticresonance(MR) imaging. MATERIALS AND METHODS: We retrospectively reviewed the MR images of 23 patients withclinically and bacteriologically proven masticator space infection, with attention to the involved structures,spread pattern, abscess formation, mandibular involvement, and etiology. RESULTS: The masseter muscle wasinvolved in 21 of 23 cases, while the cases, medial pterygoid, lateral pterygoid, and temporalis muscles wereinvolved in 14, 12, and 13 cases, respectively. All muscles in the masticator space were involved in eight casesand only a single muscle in five. In all but one case, extension through the muscle plane was noted, and in 10cases, transfascial extension was seen. Abscess formation was noted in seven cases. Mandibular involvement wasseen in 16 cases, half of which showed focal cortical disruption. The source of infection was odontogenous in 15cases, with frequent involvement of the mandible and masseter. CONCLUSION: Masticator space infection frequentlyoriginated from an odontogenous source. The characteristic MR appearances of this infection included extensionthrough the muscle plane and frequent transfascial spread to adjacent deep cervical spaces, as well as commonmandibular involvement with or without cortical disruption of focal pattern.

Usefulness of Sonography in Detection of Local Recurrent Soft Tissue Tumors

PURPOSE: To evaluate the usefulness of ultrasonography in the diagnosis of local recurrent soft tissue tumors. MATERIALS AND METHODS: We retrospectively analysed the results of 113 sonographic examinations in 102 patients (38males, 64 females) after surgical treatment of soft tissue tumors (82 malignancies, 20 benignancies) during thelast five years. Follow-up included physical and sonographic examinations using a 5-10MHz transducer every twomonths. In 17 cases, MR images were obtained The criterion for local recurrence was discrete mass, and size,shape, margin, echogenicity, and homogeneity were also analysed. Forty-one patients underwent surgery. RESULTS: Among 113 cases, 41 local recurrences were proven by surgery and histological analysis; well-defined, ovoid,homogeneous hypoechoic masses of various sizes were apparent. Sonographic sensitivity and specificity were both97%. MR sensitivity and specificity were 83% and 100% respectively, but in most cases in which MR had been usedthe masses were greater than 3cm in diameter. Two cases were false positive; these were thought to be granulomas,but were shown during follow-up lasting 36 and 14 months, respectively, to be unchanged hypoechoic nodules. Onecase was false negative. CONCLUSION: For the diagnosis of local recurrent soft tissue tumors, ultrasonography isvery useful. For early detcction, it is superior to MR imaging.

Musculoskeletal Adipose tumors of the extremities: Benign vs Malignancy in MR Imaging

PURPOSE: The purpose of this study was to evaluate the MR findings of benign and malignant musculoskeletal adipose tumors and to determine the points of difference between these two types. MATERIALS AND METHODS: This study involved 41 histopathologically proven cases; 26 were benign lipoma and 15 were liposarcoma. T1- and T2-weighted images were obtained in all cases and enhancement study was performed in 15 case of benign lipoma and14 of liposarcoma. To determine MR findings and possible differences between the two groups, we retrospectively analyzed size, location, margin, degree of signal intensity, homogeneity, enhancement pattern and internal septa, as seen on MR images. RESULTS: On both T1- and T2-weighted images, all lipomas showed a signal intensity similar to that of subcutaneous fat. Twenty-one lipomas had thin and regular internal septa and three showed focal enhancement. On T1-weighted images, 13 of 15 liposarcomas showed linear strands or patchy or diffuse areas with high signal intensity, representing a fatty component. Ten liposarcomas showed inhomogeneous signal intensity and the other five, homogeneous intensity. Irregular and thick septa were seen in nine liposarcomas, and in 12 cases, nodular diffuse enhancement was documented. CONCLUSION: Homogeneity of signal intensity, enhancing pattern and internal septa might be useful MR findings for the differential diagnosis of benign lipoma and liposarcoma.

MR Findings of Primary Scalp Mass

PURPOSE: To evaluate the diagnostic value of MRI, we compared MR images of primary scalp mass with pathological findings. MATERIAL & METHODS: Eight cases in seven patients who had presented primary scalp mass during the previous three years were evaluated by MRI and confirmed with surgical excision and pathologic evaluation. 0.38T(Resonex 4000, USA) MRI was used and all MR images were analysed retrospectively. RESULTS: Eight pathologically confirmed cases consisted of three cases of epidermal cysts, one of steatocystoma simplex, three of neurofibromatosis and one of lymphangioma. All epidermal cysts were located in the occipital area and showed ahigher signal intensity than CSF in T1WI, and proton density and variable signal intensity in T2WI. The Steatocystoma showed a signal iniensity similar to fat in T1WI and proton density and a lower signal intensity than fat in T2WI. Neurofibromatosis accounted for three cases in two neurofibromatosis patients ; one was locatedin the right parieto-occipital area and accompanied by hematoma and skull defect ; two cases were located in the occipital and posterior cervical area of the same patient. The masses showed a higher signal intensity than musclein T1WI and hyper or iso intensity in T2WI with well enhancement. The lymphangioma showed a signal intensity similar to CSF in all pulse sequences and contained a fat component. CONCLUSION: MRI is a useful modality for evaluating primary scalp mass.

Extra-Articular Synovial Chondromatosis: A case Report

A 60-year-old female presented with a slowly growing, painful mass in the superolateral portion of the rightt high. Physical examination, roentgenography, bone scan and magnetic resonance imaging revealed a soft tissue masswith mineralization which did not involve bone or joint. A triangular-shaped, mineralized lesion was found in the superior side of the greater trochanter on simple radiograph and on magnetic resonance imaging. It had not been detected clinically, and was asymptomatic. The masses were removed en bloc and diagnosed as extra articular osteochondroma. Eight months postoperatively, pain had almost been relieved.