颅内软骨瘤的CT和MRI表现与病理对照

目的探讨颅内软骨瘤的CT和MRI特征及其病理基础。资料与方法回顾性分析5例经手术病理证实的颅内软骨瘤的影像学表现。5例均行头颅CT、MRI平扫及增强扫描。结果 5例中肿瘤位于颅底者4例,大脑镰区者1例。CT表现为不规则分叶状肿块,边界清楚,密度不均匀,5例伴明显钙化,瘤周无水肿,4例邻近骨质破坏,增强扫描无或轻度强化。MRI上肿块信号不均,实质部分T1Wl呈低或混杂信号,T2WI呈高或高低混杂信号,钙化部分T1Wl及T2WI呈低信号,增强扫描5例均为明显不均匀强化,呈"石榴籽征"。结论颅内软骨瘤的CT、MRI表现具有一定特征性,结合临床,可提高其诊断准确率。     

颅内软骨瘤的CT、MRI诊断

目的总结探讨颅内软骨瘤的CT、MRI特点。方法对1994年1月至2004年9月经手术病理证实的10例颅内软骨瘤的CT、MRI特点进行回顾性分析。结果10例中，肿瘤位于颅底4例，大脑凸面4例，大脑镰区、脑实质内各1例；CT上均见到明显的钙化且边缘清楚，密度多不均匀（9例），相邻骨质可受累（5例）；于MRI上呈混杂信号（4例），其中钙化部分呈长T1、短T2信号，实质部分呈等长T1、长T2信号；CT增强扫描出现轻度强化4例，其中3例为延迟强化。结论颅内软骨瘤好发于颅底、大脑凸面及大脑镰区，多数伴有明显钙化，增强扫描呈轻度强化，延迟强化较有特点。病理仍是主要的确诊手段。     

Magnetic resonance (MR) imaging of chordoma and chondroma in the skull base--differential diagnosis by IR sequence]

Differential diagnosis of chordoma and chondroma in the skull base is sometimes difficult. We retrospectively reviewed the MR images of 14 patients with skull base tumors (nine chordomas, four chondromas and one chondrosarcoma). MR imaging was performed with a 0.5 Tesla system (Picker International). Inversion recovery (IR) (2500-2100/600-500/40), T1-weighted spin echo (SE) (800-600/40), and T2-weighted SE (2500-1800/120) images were obtained. On IR images, seven of eight chordomas showed heterogeneous low signal intensity, and one chordoma and all chondromas showed markedly low signal intensity similar to that of CSF. Calcified or ossified portions of the chondromas were demonstrated as areas of moderately low intensity on IR images. Chondrosarcoma showed moderately low intensity similar to that of chordoma. T1-weighted SE images of chordoma and chondroma showed no difference in signal intensity. On T2-weighed SE images, six of nine chordomas and all chondromas showed markedly high signal intensity. Three chordomas and one chondrosarcoma showed moderately high signal intensity. In the diagnosis of skull base tumors, the IR sequence seems to be useful for differentiating chondroma from chordoma.     

Synovial chondroma of the ankle in a young child after recent trauma: CT and MR features

We report a case of synovial chondroma of the left ankle in an 11-year-old boy presenting with soft tissue swelling after recent trauma. The noncalcified or nonossified intraarticular chondroma arising from metaplastic synovium has characteristic imaging appearance on computed tomography (CT) and magnetic resonance imaging (MRI). A lobulated mass of fluid-like density and signal intensity along with internal septa are characteristic features on CT and MRI. The knowledge of CT and MRI features of noncalcified or nonossified synovial chondroma is important to distinguish from the simple or complicated effusion, hemarthrosis, or other synovial process.     

MR imaging differentiation of soft-tissue hemangiomas from malignant soft-tissue masses

OBJECTIVE: The purpose of this study was to determine whether MR imaging features can reliably distinguish hemangiomas from malignant soft-tissue masses. MATERIALS AND METHODS: We retrospectively reviewed MR imaging studies of 22 patients with soft-tissue hemangiomas and 22 patients with malignant soft-tissue masses. Images were reviewed and agreement reached by a consensus interpretation of two observers and by an independent observer. Masses were evaluated for signal intensity on T1- and T2-weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots). Lesion T2 signal and lesion enhancement with gadolinium administration were also objectively measured using regions of interest and comparison with skeletal muscle. RESULTS: Signal intensity on T1-weighted imaging of hemangiomas and malignant soft-tissue masses was similar. Subjective analysis showed greater T2 signal and gadolinium enhancement in hemangiomas; however, the differences were not statistically significant on objective analysis. Lobulation, septation, and central low-signal-intensity dots were all more common in hemangiomas, with statistical significance achieved; the combination of all three findings was specific for hemangioma. CONCLUSION: Although no single MR imaging feature was diagnostic in this study, analysis of lesion morphology, signal intensity, and enhancement with gadolinium allowed MR imaging differentiation of hemangiomas from malignant soft-tissue masses.     

A large soft-tissue chondroma arising from the posterior mediastinum

A case of a large intrathoracic soft-tissue chondroma arising from the posterior mediastinum is described. The plain radiographic and computed tomography (CT) findings are correlated with the histopathology.     

Benign soft tissue chondroma of the foot

Soft tissue chondroma is an uncommon soft-tissue cartilaginous tumor of benign nature, it considers a variant of extra-skeletal chondromas that undergoes extensive ossification. This case of a 37?years old Egyptian male presented with a recurrent slowly growing painful palpable heel mass arises at the plantar aspect of his RT foot.The case is pathologically proven to be benign soft tissue chondroma.     

Hyperintense globus pallidus on T1-weighted MR imaging in acute kernicterus: is it common or rare?

Globus pallidus involvement is a well-known magnetic resonance (MR) imaging finding of acute kernicterus. However, it is not clear how early the involvement of globus pallidus occurs and whether or not it is seen in every case. Therefore, we aimed to investigate the globus pallidus involvement in 13 neonates with acute kernicterus by MR imaging. Thirteen neonates who were admitted with jaundice, encephalopathy and indirect hyperbilirubinemia (mean, 37.0 mg/dl) were prospectively evaluated with cranial MR imaging. Pathological signal changes were noted concerning the globus pallidus. Eight of the 13 patients demonstrated bilateral, symmetric increased signal intensity in the globus pallidus on T1-weighted MR imaging. These lesions were not apparent on T2-weighted images. Multiple parenchymal punctuate T1 hyperintense lesions were detected in one patient without globus pallidus involvement. This appearance was consistent with hemorrhage. The MR imaging findings of the other four patients showed no evidence of abnormality. The symmetric involvement of globus pallidus seen as hyperintense on T1-weighted MR imaging is a common and characteristic finding of acute kernicterus.     

Periosteal chondroma presenting as a subcutaneous mass in the thumb

We describe an unusual case of periosteal chondroma of the distal phalanx in the left thumb presenting as a subcutaneous mass in an 81-year-old woman. Magnetic resonance (MR) imaging demonstrated a subcutaneous lesion with hypointensity on T1-weighted images and marked hyperintensity on T2-weighted images, eroding the underlying cortical bone. Computed tomographic (CT) scans showed an erosive change in the dorsal cortex of the distal phalanx. Bone tumors arising from bone surface should be considered in the differential diagnosis of subcutaneous finger masses.     

Soft-tissue tumors of the hand and wrist of children

We report 23 children with soft-tissue tumors of the hand and wrist. Tumors of blood and lymph vessel origin accounted for nine patients; giant-cell tumors of tendon sheaths and tumoral calcinosis occurred in four patients each and soft-tissue chondroma in three. Synovial osteochondromatosis and aggressive fibromatosis were each represented by one patient. Finally, there was one child with a malignant soft-tissue tumor, an embryonal rhabdomyosarcoma of the hand. Hand and wrist ganglia were excluded. Imaging methods used in investigating hand and wrist lesions are discussed but plain radiography remains the first and often only examination necessary.     

Unusual location of an intracranial chondroma.

We describe the MR findings in a case of chondroma arising from the falx. At MR imaging, the mass appeared well defined, lobulated, hypointense to isointense on T1-weighted images, and very heterogeneous with marked hyperintense areas on T2-weighted images. After contrast administration, this tumor enhanced slightly on delayed images.     

Soft-tissue tumors of the foot: value of MR imaging for specific diagnosis

We reviewed MR imaging findings in 14 patients with primary soft-tissue tumors of the foot and compared them with surgical and pathologic findings to determine the value of MR imaging in anatomic localization, delineation, and characterization of such lesions. Nine tumors (64%) were benign, and five (36%) were malignant. The anatomic location (compartment, space, relation to specific tendon) and extent of all tumors were accurately shown by MR imaging. Twelve tumors (86%) were correctly characterized as benign or malignant. Eight (89%) of nine benign lesions showed distinctive MR imaging features that correctly suggested a specific diagnosis. These included hemangioma (high T2-weighted intensity and internal septa), ganglion cyst (homogeneous, high T2-weighted weighted intensity and peritendinous location), plantar fibromatosis (nodularity of plantar aponeurosis with low intensity on all sequences), and pigmented villonodular synovitis (low T2-weighted intensity and lower intensity rim). Aggressive fibromatosis (one case) could not be characterized. Four (80%) of five malignant neoplasms had MR imaging findings suggesting soft-tissue sarcoma. Two synovial sarcomas were inhomogeneous and showed extensive peritendinous growth. Two clear cell sarcomas arose at the origin of the plantar aponeurosis and infiltrated adjacent muscle. A small clear cell sarcoma could not be characterized as benign or malignant. MR imaging of the foot is accurate in showing the extent of soft-tissue tumors, which is helpful for surgical planning. Determination of their specific anatomic location may help characterize some tumors. Although our series is small, it appears that MR imaging often suggests a specific diagnosis in certain benign soft-tissue tumors of the foot and may often correctly distinguish benign from malignant tumors.     

Concurrent periosteal chondroma and enchondroma of the fibula mimicking chondrosarcoma

We present a rare concurrence of enchondroma and periosteal chondroma in the right distal fibula that mimicked chondrosarcoma in a 13-year-old boy. Radiographs and CT scans showed a periosteal lesion producing saucerization without periosteal reaction and calcification in the distal metaphysis of the right fibula. MRI showed an intramedullary lesion adjacent to the periosteal lesion, although it was invisible at CT. There was no cortical breach on imaging and gross examination. Because both lesions represented benign cartilaginous tumors on histology, concurrent periosteal chondroma and enchondroma of the fibula was diagnosed. This combination in the same bone in a patient without enchondromatosis is exceedingly rare. Such imaging features may be confused with those of chondrosarcoma.     

Brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism: CT and MR imaging findings

We present a case of brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism. CT showed an expansile soft-tissue attenuation mass centered in the sphenoid sinus. CT at bone window setting demonstrated expansile, lytic change and remodeling of the surrounding bone. On MR imaging, the lesion showed iso-intensity to gray matter on T1-weighted images and heterogeneous hyperintensity on T2-weighted images, and showed intense enhancement. The extent of the lesion and its relationship to the surrounding structures were best evaluated by CT and MR imaging.     

Soft-tissue sarcomas: use of textural patterns in skeletal muscle as a diagnostic feature in postoperative MR imaging.

The authors assessed the value of tissue textural patterns as a diagnostic feature for differentiating nonspecific posttreatment tissue changes from musculoskeletal sarcoma recurrence on magnetic resonance (MR) images. The MR imaging studies of 40 patients who had previously undergone surgery and radiation therapy for soft-tissue sarcomas of the lower extremities were evaluated in a blind fashion. In 31 of the MR imaging studies, T2-weighted images demonstrated diffuse areas of high signal intensity in soft tissues at the operative region. Close examination of the corresponding regions on high-resolution transverse T1-weighted images demonstrated textural features typical of skeletal muscle in 23 patients and the absence of such features in eight. None of the 23 patients with the "texture sign" proved to have macroscopic tumor recurrence at clinical or surgical follow-up. Among the eight patients without recognizable textural features of muscle in the regions suspicious for tumor recurrence, two proved to have recurrent tumor at surgery. Recognition of a texture sign on high-resolution T1-weighted spin-echo images of regions suggestive of tumor recurrence helps improve the diagnostic specificity of follow-up MR examinations in patients who have undergone treatment for soft-tissue sarcomas.     

Infantile lipofibromatosis of the upper limb

The imaging features of extensive lipofibromatosis presenting in a 1-day-old female infant are reported. This lesion involved her entire right upper limb, extending from the axilla to the palm of the hand. Radiographs showed marked deformity and thinning of all the right upper-limb bones due to pressure effect of soft-tissue enlargement, especially affecting the distal humerus and proximal forearm bones. Magnetic resonance imaging showed a huge soft-tissue mass infiltrating most of the muscles of the entire upper limb, with bony erosion. The mass was largely T1-isointense, moderately T2-hyperintense and showed marked enhancement. There were intra-lesional signal changes consistent with fatty elements. A lesion debulking procedure was performed and the histology was that of lipofibromatosis. The limb was found to be non-viable after the procedure and a subsequent above-elbow amputation was performed. Although the resection margins were not clear, she had no further recurrence over a subsequent 3-year follow-up period. This case (case number 16) was presented at the 31st Closed Meeting of the International Skeletal Society held in Malta, October 2004     

Proliferating trichilemmal tumors: CT and MR imaging findings in two cases, one with malignant transformation

We report the imaging findings in two patients with proliferating trichilemmal tumors. In the first patient, the tumor arose on the lower lip, a very unusual location for this type of tumor, and showed malignant transformation with metastasis to a regional lymph node. It was seen as a poorly marginated soft-tissue mass with isointense signal on T1-weighted MR images and hyperintense signal on T2-weighted images. Large areas of high signal intensity caused by necrosis were also found within the tumor on T2-weighted images. After i.v. administration of contrast material, the mass showed significant enhancement, with considerable portions remaining unenhanced. In the second patient, the tumor originated from a preexisting trichilemmal cyst and occurred in the hair-bearing area of the posterior part of the neck. CT scans showed a well-encapsulated cystic mass that contained multiple speckled calcifications in a wall of variable thickness. There were several foci of smooth soft-tissue elevations from the inner wall of the mass, which corresponded histologically to proliferating portions of trichilemmal cyst.     

磁共振成像弛豫时间测定在颅内肿瘤组织定性诊断中的价值

目的：探讨磁共振成像序列中测出的弛豫时间在确定颅内肿瘤组织类型方面的价值。材料和方法：选用最佳参数成像后对有病理证实的３４例（１１种）颅内肿瘤的弛豫时间进行测定和分析。结果：星形细胞瘤、室管膜瘤、髓母细胞瘤及神经纤维瘤病的Ｔ１延长最为明显，Ｔ２也较长。转移瘤、垂体瘤及软骨瘤的Ｔ１、Ｔ２呈中度延长。囊性颅咽管瘤可呈短Ｔ１长Ｔ２表现。听神经鞘瘤的Ｔ１最短，与其它肿瘤无重叠，Ｔ２则较长。结论：部份肿瘤的弛豫时间较有特征性，可用作鉴别诊断的参考，大部份肿瘤的弛豫时间在分布上弥散和重叠明显，不能明确分界，因而不能单凭弛豫时间作出组织类型诊断。     

MR findings of penile lymphoma

Penile lymphoma is extremely rare and secondary involvement of the penis by lymphoma may be due to retrograde spread or to direct extension from neighbouring organ. The appearance of penile lymphoma varies and can be mistaken for other soft tissue tumours. We report on a case with malignant lymphoma of the penis. MRI findings revealed soft-tissue mass of homogeneous isointensity around the middle to distal part of penis on T(1) weighted imaging and T(2) weighted imaging. It was well encapsulated, minimally enhanced and distinct from corpus cavernosum and corpus spongiosum.     

Soft-tissue masses: histologic basis for decreased signal (short T2) on T2-weighted MR images

Most soft-tissue masses and tumors of various etiologies and histologies have high signal intensity on T2-weighted pulse sequences (long T2). Of 47 soft-tissue masses, seven had a low signal (short T2) on T2-weighted pulse sequences. All seven masses were tumors, and histologic review showed that their composition differed from that of the other 40 lesions with a long T2 in that the seven masses were relatively acellular and had more collagen. The tumors with a short T2 included one malignant and six benign soft-tissue tumors. Malignant fibrous histiocytoma and aggressive fibromatosis showed paradoxical signal intensities in that they showed both long and short T2. All of the tumors with low signal intensity on T2-weighted images had significant fibrous elements and marked hypocellularity. This study suggests that the less commonly encountered short T2 may be seen in both benign and malignant soft-tissue lesions. A part of the explanation for the low signal on T2-weighted sequences appears to be the relative acellularity and abundant collagen of these tumors in comparison with those that have the same histologic diagnoses but show a high signal. The histologic composition of the tumor rather than the histologic diagnosis appears to influence the MR signal on T2-weighted sequences.