Magnetic resonance imaging of soft tissue tumors of the hand and wrist

We will discuss the imaging characteristics of soft tissue tumors of the hand and wrist, especially the magnetic resonance imaging findings, since MRI has proven to be the gold standard for characterization of soft tissue tumors. Our series consists of 71 tumors of the hand and wrist, that were examined by magnetic resonance imaging. Fourty-four lesions were benign, 7 malignant, and 20 lesions were pseudotumoral masses. The signal characteristics often allow to make a correct diagnosis or to narrow down the list of differential diagnoses. It also allows to determine the extent of the lesion more accurately.     

Soft tissue masses in the foot and ankle: characteristics on MR Imaging

Benign neoplasms and tumor-like lesions constitute the majority of soft tissue masses in the foot and ankle. Therefore, malignant tumors are often unsuspected at this site and misdiagnosed clinically, especially if occurring in young individuals with unspecific or long-standing clinical symptoms. In addition to radiography, MR imaging represents the method of choice in evaluation of foot tumors. Because of their relatively characteristic imaging appearance, in most cases of benign soft tissue lesions of the foot and ankle a specific diagnosis can be suggested. Unfortunately, malignant tumors can also arise with nonaggressive imaging features. Diagnostic errors can be avoided if any soft tissue lesion that cannot be specifically diagnosed is regarded as potentially malignant until proved otherwise. This article reviews the MR appearance of the most common benign and malignant soft tissue masses in the foot and ankle together with their clinical, radiographic, and pathological findings.     

MR Imaging of Soft Tissue Tumors: An Overview

Over the past decade, magnetic resonance (MR) imaging has been established as the most widely used examination for the detection of a suspected soft tissue mass and often for depiction of the extent and the characterization of the mass. Sensitivity of the examination for the detection of soft tissue masses is high but specificity is limited. With experience accrued over the past decade, radiologists are increasingly able to predict the histology of lesions based on MR imaging criteria. However, because of the overlap of morphologic features of benign and malignant soft tissue masses, a benign-appearing mass should not be considered benign unless the tumor can be specifically named and its histology predicted by well-established MR imaging features. When a mass is not thought to be an overt sarcoma and there is uncertainty as to whether it is benign or malignant, the tumor should be characterized as indeterminate and approached as a sarcoma until proven otherwise. This article reviews MR imaging in diagnosing and staging soft tissue masses and briefly discusses the radiologist?s approach to percutaneous biopsy of indeterminate soft tissue masses.     

The clinical evaluation of soft tissue tumors

Soft tissue tumors range from benign subcutaneous lipomas to malignant deep high-grade sarcomas. Patients are evaluated with a thorough history and physical examination followed by imaging studies. Magnetic resonance imaging is the modality of choice, although radiographs, computed tomography, and other modalities may be of value. Open or closed biopsy can be performed to establish a diagnosis. Treatment depends on the diagnosis and includes observation or marginal excision for benign lesions and wide resection for malignant masses, with radiation therapy or chemotherapy for large, high-grade tumors. An algorithm for the evaluation, diagnosis, and treatment of soft tissue tumors is presented.     

Cross-sectional imaging with CT and/or MRI of pediatric chest tumors

The purpose of this study was to provide an overview of the spectrum of pediatric chest masses, to present the results of cross-sectional imaging with CT and/or MRI, and to define diagnostic criteria to limit differential diagnosis. Seventy-eight children with thoracic mass lesions were retrospectively evaluated using CT (72 patients) and/or MR imaging (12 patients). All masses were evaluated for tissue characteristics (attenuation values or signal intensity, enhancement, and calcification) and were differentiated according to age, gender, location, and etiology. Twenty-eight of 38 (74 %) mediastinal masses were malignant (neuroblastoma, malignant lymphoma). Thirty of 38 (79 %) pulmonary masses were metastatic in origin, all with an already known primary tumor (osteosarcoma, Wilms tumor). With one exception, all remaining pulmonary lesions were benign. Seventeen of 21 (81 %) chest wall lesions were malignant (Ewing sarcoma, primitive neuroectodermal tumor). The majority of mediastinal and chest wall tumors in children is malignant. Lung lesions are usually benign, unless a known extrapulmonary tumor suggests pulmonary metastases. Cross-sectional imaging with CT and/or MRI allows narrowing of the differential diagnosis of pediatric chest masses substantially by defining the origin and tissue characteristics. Magnetic resonance imaging is preferred for posterior mediastinal lesions, whereas CT should be used for pulmonary lesions. For the residual locations both modalities are complementary. Received 7 March 1997; Revision received 9 September 1997; Accepted 14 November 1997     

FDG-PET for preoperative differential diagnosis between benign and malignant soft tissue masses

OBJECTIVE: To evaluate the standardized uptake value (SUV) of [(18)F]2-deoxy-2-fluoro- d-glucose at positron emission tomography (FDG-PET) for preoperative differential diagnosis between benign and malignant soft tissue masses. DESIGN: One hundred and fourteen soft tissue masses (80 benign, 34 malignant) were examined by FDG-PET prior to tissue diagnosis. The SUVs were calculated and compared between benign and malignant lesions and among different histologic subgroups which included three or more cases. RESULTS: There was a statistically significant difference in SUV between benign (1.80+/-1.42 [SD]) and malignant (4.20+/-3.16) soft tissue masses in total (P<0.0001). However, a considerable overlap in SUV was observed between many benign and malignant lesions. Liposarcomas (2.16+/-1.72) and synovial sarcomas (1.60+/-0.43) did not show significantly higher SUV than any benign lesions. Metastases (4.23+/-2.35) showed no statistically significant difference in SUV as compared with schwannomas (1.75+/-0.84), desmoids (2.77+/-1.32), sarcoidosis (3.62+/-1.53), or giant cell tumors of tendon sheath (GCT of TS; 5.06+/-1.63). Even malignant fibrous histiocytomas (5.37+/-1.40) could not be differentiated from sarcoidosis or GCT of TS, based on the SUV. CONCLUSIONS: A large accumulation of FDG can be observed in both benign and malignant histiocytic, fibroblastic, or neurogenic lesions. SUV at conventional FDG-PET is limited to differentiating benign from malignant soft tissue masses, when all kinds of histologic subtypes are included.     

Imaging and diagnostic strategy of soft tissue tumors in children

The diagnosis of a soft tissue mass in children is a common clinical situation. Most of the lesions are benign and can be treated conservatively or by non-mutilating surgery. Nevertheless, the possibility of a malignant soft tissue tumor must be systematically considered. The most frequent benign soft tissue lesions in children are vascular lesions, fibrous and fibrohistiocytic tumors and pseudotumors, whereas rhabdomyosarcomas account for 50% of all soft tissue sarcomas. A child presenting an atypical soft tissue mass should be managed by a multidisciplinary centre, and primary resection must be proscribed until a definite diagnosis has been established. The role of imaging is essential either to confirm the benign nature of the mass or to give arguments to perform a diagnostic biopsy. Clinical examination, conventional radiography and ultrasound with Doppler represent the first-line examinations and are sometimes sufficient to assess a diagnosis. In all other situations, MRI is mandatory to establish the probable nature of the lesion and to assess local extension.     

Nerve sheath tumors: evaluation with CT and MR imaging.

Tumors of nerves are classified into benign (schwannoma and neurofibroma) and malignant nerve sheath tumors. Schwannomas almost always occur as solitary lesions, whereas neurofibromas may occur alone or in a greater number, especially in patients with the peripheral form of von Recklinghausen's disease. Benign nerve sheath tumors often present as asymptomatic, slowly growing soft tissue masses. Although malignant nerve sheath tumors are relatively rare, a sudden increase in the size of a lesion, in particular in a patient with neurofibromatosis, should raise the suspicion of malignant change. On computed tomography (CT) and magnetic resonance imaging (MR) a benign nerve sheath tumor usually appears as a well-defined, oval, spherical or fusiform mass with smooth borders and distinct outlines, located in the subcutaneous tissue or centered at the expected anatomic location of a nerve, with displacement of adjacent soft tissues. Generally nerve sheath tumors have a low density on unenhanced CT scans. On MR they are isointense to muscle on T1-weighted images, whereas on T2-weighted images the signal intensity is high. Both on CT and MR the degree of contrast enhancement is moderate to marked and may be homogeneous or inhomogeneous. MR has become the method of choice for evaluating the anatomic location, contour, and relation of a nerve sheath tumor to adjacent neural, vascular, and muscular structures. The imaging criteria for malignant nerve sheath tumors are not specific enough to distinguish them from other malignant soft tissue tumors, so that neither CT nor MR can establish a definite diagnosis.     

Ultrasound in musculoskeletal tumors with emphasis on its role in tumor follow-up.

Ultrasonography allows visualization of musculoskeletal masses that are not confined to the intraosseous compartment and assists in the determination of the consistency of such masses. Making a specific diagnosis using ultrasonography is hampered by the lack of specificity; however, it may be an indicator in guiding diagnostic needle biopsy, especially in large heterogeneous tumors. Color Doppler flow imaging allows visualization of blood flow within solid soft tissue masses. Probably, CDFI features do not assist in differentiation between malignant and benign tumors; however, it has proved to be a useful tool to monitor regression of tumor neovascularity induced by therapy in patients with musculoskeletal sarcoma. When recurrence of a soft tissue sarcoma is clinically suspected, ultrasonography can be used as the initial imaging technique for evaluation. Ultrasonography can also be used in addition to MR imaging when susceptibility artifacts secondary to orthopedic hardware (including prostheses) prevent evaluation of specific areas.     

Imaging of Soft Tissue Neoplasms in the Adult: Benign Tumors

This discussion reviews the spectrum of benign soft tissue tumors usually found in adults. Lesions most commonly identified in the pediatric population, tumorlike masses, and malignant tumors are discussed in other articles in this issue. Rather than presenting a complete review, the focus of this article is on benign tumors in which the diagnosis may be confidently made or strongly suggested on the basis of imaging. Diagnoses presented include those for lipoma, lipoma variants, giant cell tumor of the tendon sheath, pigmented villonodular synovitis, superficial and deep fibromatoses, elastofibroma, and peripheral nerve sheath tumors.     

Angiography of extremity masses in children.

Arteriography has proved useful in evaluating 24 children with soft tissue extremity masses. In all cases, it was possible to distinguish between benigna and malignant tumors. The five patients with malignant tumors had increased vascularity with coarse irregular vessels and irregular tumor staining. Arteriovenous shunting was present in three of these five. In addition, clinically unsuspected satellite tumors (local metastases) were seen in two patients. Arteriography in 19 patients with benign conditions was characteristic. Benign tumors of non-blood vessel origin (five) showed only arterial displacement but no pathologic circulation. Five hemangiomas and six arteriovenous malformations were easily distinguished; characteristic appearances were present in three patients with miscellaneous benign masses.     

慢性结核性脓胸合并恶性肿瘤的影像诊断(附3例报告)

目的探讨慢性结核性脓胸合并恶性肿瘤的临床与影像学表现。方法对我院发现经病理证实的3例慢性结核性脓胸合并恶性肿瘤病例进行影像分析,并复习相关文献。结果胸片及CT均示患侧胸膜增厚、钙化,脓胸肺侧出现软组织肿块,肿块与脓胸壁连续移行,该处钙化影移位、散开、减少、中断,肿块密度较均匀(1例)或欠均匀(2例)。结论慢性结核性脓胸合并恶性肿瘤的影像表现有一定特征性,尤其钙化影改变、软组织块的出现及胸壁脂肪界面不清,更有诊断价值。     

Pediatric liver tumors – a pictorial review

Hepatic masses constitute about 5–6% of all intra-abdominal masses in children. The majority of liver tumors in children are malignant; these malignant liver tumors constitute the third most common intra-abdominal malignancy in the pediatric age group after Wilms’ tumor and neuroblastoma. Only about one third of the liver tumors are benign. A differential diagnosis of liver tumors in children can be obtained based on the age of the child, clinical information (in particular AFP) and imaging characteristics. The purpose of this review is to report typical clinical and imaging characteristics of benign and malignant primary liver tumors in children.     

纵隔生殖细胞源性肿瘤的CT诊断和鉴别诊断(附32例报告)

目的总结纵隔生殖细胞源性肿瘤的CT表现及良、恶性的鉴别要点。方法回顾性分析32例经手术病理证实的纵隔生殖细胞源性肿瘤。结果32例中,良性生殖细胞源性肿瘤26例,其中囊性肿块10例,实性肿块9例,囊实性肿块7例;恶性生殖细胞源性肿瘤6例,其中精原细胞瘤、内胚窦(卵黄囊)瘤及胚胎细胞癌各1例和恶性畸胎瘤3例。典型的良性畸胎类肿瘤显示水样至软组织密度肿块,边缘清晰,其内有脂肪或钙化等,推移压迫周围组织,恶性肿瘤具有边缘分叶状或不规则,与周围组织脂肪间隙消失并侵犯相邻器官的征象。结论CT对纵隔良性生殖细胞源性肿瘤能准确作出诊断,纵隔恶性生殖细胞源性肿瘤难以与纵隔其它恶性肿瘤区分。     

Diagnostic imaging of mediastinal masses in children.

Mediastinal masses are the most common thoracic masses in children. The encyclopedic list of diagnostic considerations can be distilled into a concise and practical differential diagnosis based on the location of the mass and the established prevalence of various tumors and pseudotumors in the mediastinal compartments. Malignant lymphoma, benign thymic enlargement, teratomas, foregut cysts, and neurogenic tumors make up 80% of mediastinal masses in children. Continuing advances in imaging technology have altered traditional approaches to the evaluation and diagnosis of mediastinal masses in children. Plain chest radiography remains the basic imaging examination to define location and morphology. Cross-sectional imaging subsequently clarifies the morphology and extent of the mass. In general, CT is the primary cross-sectional imaging procedure in the evaluation of most mediastinal masses in children. Exceptions to this rule include MR in children with posterior mediastinal masses or suspected vascular lesions: in such cases, MR imaging is the preferred initial postradiographic examination. Sonographic examination may be diagnostic in foregut cysts and some other mediastinal masses. Gallium-67 scintigraphy has an emerging role in management of malignant lymphoma.     

胸膜原发性肿瘤的影像学诊断(附26例分析)

目的：分析胸膜原发性肿瘤的影像学特点，探讨胸膜原发性肿瘤与肺内肿块鉴别诊断的要点。方法：回顾性分析26例经手术病理证实的原发性胸膜肿瘤的影偈学资料，其中，胸膜间皮瘤20例，胸膜神经鞘瘤4例，神经纤维瘤1例及胸膜纤维脂肪瘤1例。结果：胸膜间皮瘤影偈学表现为3种类型；单发胸膜肿块型，多发胸膜肿块及结节状胸膜增厚型，胸膜积液为主型，单发肿块良，恶性均有，多发性肿块或结节状胸膜增厚伴胸腔积液时，多见于恶性弥漫型胸膜间皮瘤，胸膜神经鞘瘤，神经纤维瘤及胸膜纤维脂肪瘤均具有良性肿瘤的特征。结论：胸膜原发性肿瘤虽无特征性影像学表现，仔细综合分析各种影像学征象特点，对提高本病的诊断具有重要价值。     

Radionuclide imaging of soft tissue neoplasms

Two classes of radiopharmaceuticals may be used for imaging tumors of the musculoskeletal system. The first is comprised of soft tissue or tumor specific agents such as gallium-67, bleomycin, and radionuclide-labeled antibodies, which may be useful for detecting and localizing these tumors. The other class of tracer is comprised of those with avidity for bone. The 99mTc-labeled-phosphate skeletal imaging compounds have been found to localize in a variety of soft tissue lesions, including benign and malignant tumors. In 1972, Enneking began to include bone scans in the preoperative evaluation of soft tissue masses. Later, he and his associates reported that these scans were useful in planning operative treatment of sarcomas by detecting involvement of bone by the tumors. Nearly all malignant soft tissue tumors take up bone-seeking radiopharmaceuticals, and bone involvement was indicated in two-thirds of the scans we reviewed. About half of benign soft tissue lesions had normal scans, but the other half showed uptake within the lesion and a few also showed bone involvement. Careful, thorough imaging technique is essential to proper evaluation. Multiple, high-resolution static gamma camera images in different projections are necessary to adequately demonstrate the presence or absence of soft tissue abnormality and to define the precise relationship of the tumor to the adjacent bone.     

Chondroid lipoma: correlation of imaging findings and histopathology of an unusual benign lesion

The imaging findings of soft tissue tumours are often non-specific and generally require biopsy to differentiate between benign and malignant lesions. The finding of curvilinear, annular or amorphous mineralisation in an enlarging mass has sinister connotations. In this case report, we present the imaging findings with histological correlation of a chondroid lipoma, an unusual benign soft tissue tumour, which presented with radiographic evidence of calcification, an imaging finding not previously described. We also describe the ultrasound appearance and certain MR imaging appearances that have not been previously attributed to this tumour in the few reported cases.     

Computer-aided diagnosis of peripheral soft tissue masses based on ultrasound imaging

Medical ultrasound (US) has been widely used for distinguishing benign from malignant peripheral soft tissue tumors. However, diagnosis by US is subjective and depends on the experience of the radiologists. The rarity of peripheral soft tissue tumors can make them easily neglected and this frequently leads to delayed diagnosis, which results in a much higher death rate than with other tumors. In this paper, we developed a computer-aided diagnosis (CAD) system to diagnose peripheral soft tissue masses on US images. We retrospectively evaluated 49 cases of pathologically proven peripheral soft tissue masses (32 benign, 17 malignant). The proposed CAD system includes three main procedures: image pre-processing and region-of-interest (ROI) segmentation, feature extraction and statistics-based discriminant analysis (DA). We developed a depth-normalization factor (DNF) to compensate for the influence of the depth setting on the apparent size of the ROI. After image pre-processing and normalization, five features, namely area (A), boundary transition ratio (T), circularity (C), high intensity spots (H) and uniformity (U), were extracted from the US images. A DA function was then employed to analyze these features. A CAD algorithm was then devised for differentiating benign from malignant masses. The CAD system achieved an accuracy of 87.8%, a sensitivity of 88.2%, a specificity of 87.5%, a positive predictive value (PPV) 78.9% and a negative predictive value (NPV) 93.3%. These results indicate that the CAD system is valuable as a means of providing a second diagnostic opinion when radiologists carry out peripheral soft tissue mass diagnosis.     

Ultrasound evaluation of soft tissue tumors.

Because of its availability, ultrasound should be the preferred initial modality for the evaluation of palpable superficial masses. Most ultrasound units are equipped with high frequency probes that allow superficial focalization. The differential diagnosis of soft tissue masses and the sonographic features of some benign and malignant soft tissue lesions are reviewed in this article. After an initial ultrasound evaluation confirming the presence of a tumor, the need for and the role of other imaging modalities can be determined. In selected cases ultrasound may obviate the need for further imaging. MRI and CT should be reserved for cases in which sonography fails to establish a specific diagnosis or to demonstrate the limits of the soft tissue mass.