On T1-weighted images, lesions were isointense (n=3), hypointense (n=7) or slightly hyperintense to muscle (n=11). In such situations, it is useful to formulate a suitably ordered differential diagnosis on the basis of a knowledge of tumor prevalence, patient age, and lesion anatomic location. Gadolinium-enhanced imaging has also been proposed as useful in differentiating benign and malignant soft-tissue lesions, with malignant lesions showing a greater enhancement as well as a greater rate of enhancement [43, 45, 47, 60]. Tumors and pseudotumors of the soft tissues: Imaging semiology and strategy. Severe reactions have been reported with both gadopentetate dimeglumine (Magnevist; Berlex Laboratories, Wayne, NJ) and gadoteridol (ProHance; Squibb Diagnostics, Princeton, NJ), including hypotension, laryngospasm, bronchospasm, anaphylactoid reaction, and anaphylactic shock [46,47,48,49,50], as well as a full spectrum of less serious reactions. In a multiinstitutional study of 133 patients with primary soft-tissue malignancies, the Radiology Diagnostic Oncology Group found no statistically significant difference between CT and MR imaging in determining tumor involvement of muscle, bone, joint, or neurovascular structures [8]. In general, a small field of view is preferred; however, the field of view must be large enough to allow evaluation of the lesion and appropriate staging. As the presence of this relative higher signal intensity on T1-weighted images is rather specific for tumors displaying melanocytic differentiation, radiologists should familiarize themselves with this rare entity and include it in their differential diagnosis when confronted with a well-defined, homogeneous, strongly enhancing mass with slightly higher signal intensity compared with muscle on native T1-weighted images. Although initial investigations maintained that CT was superior to MR imaging in detecting destruction of cortical bone [29, 30, 35], later studies suggest that these two modalities are comparable in this regard [28, 36]. Gradient-echo imaging may be a useful supplement in revealing hemosiderin because of the greater magnetic susceptibility of hemosiderin. The concept that we should take a clinical history requires a significant change in paradigm. As sarcomas enlarge, a pseudocapsule of fibrous connective tissue is formed around them by compression and layering of normal tissue, associated inflammatory reaction, and vascularization [57]. MRI showed a network of interconnecting tubular areas, which were T1 … MR imaging is well-suited for the evaluation of soft-tissue tumors and tumorlike lesions because of its intrinsically high soft-tissue contrast and its capability to aid in imaging superficial and deep soft tissues over both large and small fields of view (20,45,46,48,49,54,58). When small superficial lesions are being evaluated, care should be taken to ensure the marker or patient position does not compress the mass. The emergence of CT improved this situation dramatically. Angiomatous lesions are quite common and are multiple in as many as 20% of patients [9]. In fact, prominent high signal intensity surrounding a soft-tissue mass more commonly suggests an inflammatory process, abscess, myositis ossificans, local trauma, hemorrhage, biopsy, or the effect of radiation therapy rather than a primary soft-tissue neoplasm (Fig. Attempts were made to develop rules analogous to those for bone tumors for differentiating benign and malignant processes on the basis of lesion morphology and signal intensity; however, with few exceptions, these rules proved unreliable [2,3,4,5,6,7]. Although these figures are based on surgical series, these trends are likely still valid for radiologists. Is MRI able to perform a specific diagnosis? MRI in bone tumors, soft-tissue sarcoma, melanoma, and lymphoma. Has the lesion remained stable over a long period of time or varied in size, or is it growing? 1). 2000 Sep-Oct;20(5C):3993-8. This pattern of growth is quite different from that seen in most primary soft-tissue tumors. Signs that had the greatest specificity for malignancy included tumor necrosis, bone or neurovascular involvement, and mean diameter of more than 66 mm (Figs. 5A,5B,5C,5D). Metastatic melanoma may display a similar pattern of multiple nodular subcutaneous metastases [24] (Fig. More recently, the superiority of MR imaging in the staging of musculoskeletal tumors has also come into question. The prognosis is poor as the disease is usually very advanced. Is there a history of a previous lesion or underlying malignancy? 7A,7B,7C,7D). The choice of an additional imaging plane or planes varies with the involved body part, the lesion location, and the lesion's relationship to crucial structures. In fields where PET/MRI data are lacking, we outline the potential role of PET/MRI on the basis of the PET/CTand MRI literature. A slowly growing soft-tissue mass that may remodel adjacent bone (causing a scalloped area with well-defined sclerotic margins) may still be highly malignant on histologic examination [9]. Aggressive fibromatosis is multifocal in 10-15% of patients [20, 21]. The imaging of soft-tissue masses was now on a par with that of other imaging-intense radiologic subspecialties, with exquisite depiction of anatomic detail. Melanoma commonly metastasizes to the breast, but metastatic involvement of the breast parenchyma is rare, accounting for 0.5 - 6.6% of all breast malignancies ( 6 - 9 ). Significance of MRI in the diagnosis and differentiation of clear cell sarcoma of tendon and aponeurosis (CCSTA): A case report. More commonly, MR imaging may reveal a nonspecific appearance. Skeletal muscle metastases from malignant melanoma are very rare. This distinction is especially important to guide biopsy and may be difficult or impossible to make on conventional T2-weighted MR images when both tumor and fluid show high signal intensity, well-defined margins, and homogeneous signal intensity. MR imaging of soft-tissue masses of the foot. Multiple lesions may also be seen with metastatic disease. Prevention and treatment information (HHS). These are also called epidermoid cysts, which in turn are sometimes considered a type of dermoid cyst 9.. Clinical presentation. Careers. Jordan and Mintz [51] described a fatal reaction to gadopentetate dimeglumine that was presumed to be caused by anaphylactic reaction with associated bronchospasm. In general, susceptibility artifacts related to metallic material, hemorrhage, and air are accentuated on gradient-echo MR images [38] (Fig. MRI has a high soft-tissue resolution, making it the best imaging technique for evaluating malignant melanoma currently. As with STIR techniques, fat-suppressed T2-weighted MR imaging decreases variations in tumor signal intensities, and we do not use this technique in place of conventional T2-weighted MR imaging. Although there is general agreement on the value of MR imaging in the detection, diagnosis, and staging of soft-tissue tumors and tumorlike lesions, the use of IV contrast material in their evaluation remains controversial. As we complete our training, we are cautioned that Board examiners will require an explanation if additional information is sought. Tomà P, Esposito F, Granata C, Paolantonio G, Terranova MC, Lo Re G, Ferrara D, Rollo M, Zeccolini M, Salerno S. Radiol Med. In 19 cases the pathology findings were available for review and for a comparative MR-pathology study. Although radiographs were sensitive to the identification of adipose tissue and soft-tissue mineralization, they provided little other diagnostic information. National Library of Medicine Soft tissue is relatively resistant to metastasis; although soft tissue accounts for about 40% of total body weight, soft-tissue metastases are very rare. 6). A subtle radiologic feature, which may help to separate inflammatory and neoplastic processes, is that an inflammatory process typically obliterates fascial planes rather than displaces them. 4.6 Portal venous phase CT of abdomen demonstrates an intramuscular metastasis from melanoma in left external oblique muscle (arrow) Fig. STIR imaging produces fat suppression and enhances the identification of abnormal tissue with increased water content and, as a result, is useful to confirm subtle areas of soft-tissue abnormality [40]. Soft tissue is relatively resistant to metastasis, and although soft tissue comprises about 40% of total body weight, soft-tissue metastases are quite rare. To evaluate MR imaging and pathology findings in order to define the characteristic features of clear cell sarcoma of the soft tissues (malignant melanoma of the soft parts). The diagnosis may be suggested on the basis of imaging findings by the identification of multiple lesions in a major nerve distribution. Soft-Tissue Chondroma. In daily practice, histories are often scant, with little substantive data. (Redirected from Soft-tissue melanoma) Clear cell sarcoma is a rare form of cancer called a sarcoma. 8,9A,9B,10A,10B). Objective: When not characteristic of a specific process, soft-tissue calcification can suggest certain diagnoses. Its MR findings are rarely described in the literature. Before the advent of computer-assisted imaging, assessment of clinically suspicious soft-tissue masses was usually limited to radiographs. ... For melanotic melanoma in particular, MRI can be diagnostic if specific features are present. The radiologic evaluation of soft-tissue masses has changed dramatically within the last two decades. Rare forms were thought to occur in the gastrointestinal tract before they were discovered to … Malignancies, by virtue of their very nature and potential for autonomous growth, are generally larger and more likely to outgrow their vascular supply with subsequent infarction, necrosis, and heterogeneous signal intensity on T2-weighted spin-echo MR imaging. Fast scanning techniques may be useful in the evaluation of soft-tissue masses. It is known to occur mainly in the soft tissues and dermis. MR imaging has emerged as the preferred modality for evaluating soft-tissue lesions [2,3,4, 28,29,30,31,32,33,34,35]. Oncologic PET/MRI, part 2: bone tumors, soft-tissue tumors, melanoma, and lymphoma. In such cases, superficial and deep lesions may coexist. Occurrence of tumor is almost equal … The most common malignant and benign lesions, by tumor location and patient age, have been previously published [13, 14]. They may add additional information and be helpful in specific instances, although fast scanning techniques have not replaced standard spin-echo imaging. Metastases are common in the subcutaneous and soft-tissue locations, and MRI has an important role in evaluating brain, bone marrow, liver, and soft-tissue metastases (3-5). Unlike bone tumors, however, a slowly growing soft-tissue mass is not invariably indicative of a benign process. In addition, most malignant tumors are deep, whereas only about 1% of all benign soft-tissue tumors are deep [55, 56]. In nine of 11 lesions with slightly increased signal intensity on T1-weighted images, a correlative MR imaging-pathology study was possible. PET/MRI seems to be of benefit in T-staging of primary bone tumors and soft-tissue sarcomas. 2021 Mar 3;11:13. doi: 10.25259/JCIS_135_2020. In addition, an approach is provided for establishing a differential diagnosis for those lesions with a nonspecific imaging appearance, as well as indications for contrast-enhanced imaging. Despite the superiority of MR imaging in delineating soft-tissue tumors, it remains limited in its ability to precisely characterize them, with most lesions showing a nonspecific appearance with prolonged T1 and T2 relaxation times. Lesions are generally well seen on standard imaging, and, in our opinion, STIR imaging tends to reduce the variations in signal intensities identified on conventional spin-echo MR imaging that are most helpful in tissue characterization. 2021 Feb 1;94(1118):20200648. doi: 10.1259/bjr.20200648. The radiologic appearance of certain soft-tissue tumors or tumorlike processes, such as myositis ossificans, fatty tumors, hemangiomas, peripheral nerve sheath tumors, pigmented villonodular synovitis, and certain hematomas may be sufficiently unique to allow a strong presumptive radiologic diagnosis. On MRI, soft tissue metastases are of low or intermediate signal intensity compared to normal muscle on T1-weighted sequences and high signal intensity on T2-weighted sequences [17, 22, 42]. Adventitious bursitis in the plantar fat pad of forefoot presenting as a tumoral mass. Despite the pathologist's best efforts, however, approximately 5-15% of soft-tissue sarcomas cannot be further classified [11,12,13,14]. Epidermal cysts are either found incidentally or … The MR imaging appearances of these lesions have been well reported and is not reviewed here. eCollection 2018 Mar. In the case of hematoma, contrast-enhanced imaging may reveal a small tumor nodule that may have been inapparent within the hemorrhage on conventional MR imaging [52, 53]. The diagnosis of a malignant bone tumor such as Ewing's sarcoma or primary lymphoma of the bone should be considered when there is a large circumferential soft-tissue mass in association with an underlying destructive permeative bone lesion. However, any malignancy may disseminate to the skin, and 5%–10% of all cancer patients develop skin metastases (, … Enhancement reflects tissue vascularity and tissue perfusion, and, in general, the rate of enhancement in malignant lesions is greater than that seen in benign lesions. Clear cell sarcoma of soft parts (tendon and aponeurosis)—CCSTA is a rare melanin producing malignant soft tissue sarcoma or malignant melanoma (MM) of soft parts, which is derived from the neural crest cells originating from soft tissue displaying melanocytic differentiation due to intralesional deposition of melanin. 4.7 This ability to accurately anatomically characterize masses spurred new interest in the evaluation of soft-tissue tumors. [61] performed a multivariate statistical analysis of 10 imaging parameters, individually and in combination. One study has suggested that MR imaging can differentiate benign from malignant masses in more than 90% of cases on the basis of the morphology of the lesion [6]. To provide further information on PET/MRI, we refer to our own unpublished experiences with PET/MRI in parts of this article. Uveal Melanoma (UM) is the most common primary malignant ocular tumor. Finally, multiple myxomas may be seen in association with fibrous dysplasia of bone (Mazabraud syndrome) [25]. A second soft-tissue mass in a patient with a previously confirmed desmoid tumor should be regarded as a second desmoid tumor until proven otherwise [22]. Edema, which is infrequent without superimposed trauma or hemorrhage, is considered to be part of the reactive zone around the neoplasm and, as a result, is removed en bloc with the tumor [44]. Multiple lipomas are seen in 5-15% of patients presenting with a soft-tissue mass [17,18,19]. Note, however, that myxoid lesions such as intramuscular myxoma or myxoid liposarcoma, and hyaline cartilage lesions such as synovial chondromatosis may show little or mild enhancement and may mimic cysts or lesions with cystic components (Fig. is not yet available for some types of tumors, potential indications are based on available PET/CT and MRI data. Although frequently unrewarding, it is impossible to predetermine those cases in which radiographs will be critical for diagnosis. Up-to-date imaging review of paediatric soft tissue vascular masses, focusing on sonography. A 31-year-old woman presented with increasing pain and tenderness of a long-standing soft tissue mass on her back. Immunohistochemical examination was performed in 17 patients. This site needs JavaScript to work properly. Only 5% of benign soft-tissue tumors exceed 5 cm in diameter [55, 56]. Mavrogenis A, Bianchi G, Stavropoulos N, Papagelopoulos P, Ruggieri P. Gandolfo N, Martinoli C, Cafiero F, Peressini A, Nicolò M, Dellachà A, Derchi LE. We generally reserve CT for patients in whom radiographs do not adequately depict the lesion, its pattern of mineralization, or its relationship to the host. This technique increases lesion conspicuity [40, 41], but it typically has a lower signal-to-noise ratio than does spin-echo imaging and is also more susceptible to degradation by motion [37, 40]. 8600 Rockville Pike In actuality, differentiation between tumor and muscle is usually quite well delineated without contrast-enhanced imaging on T2-weighted MR images, and the accurate distinction between tumor and edema is probably of little practical value. Thin fibrous septa less than 2 mm in thickness are sometimes seen ( 8 , 9 , 11 ). Consequently, gadolinium-enhanced imaging should be reserved for cases in which the results would influence patient care. Local staging is best accomplished using MR imaging, which can accurately depict the anatomic spaces (compartments) involved by the tumor [62]. For example, they may reveal phleboliths within a hemangioma (Fig. Caution is required, however, because the fibrovascular tissue in organizing hematomas may show enhancement [54]. Moreover, although the incidence of untoward reaction as a result of contrast material administration is small, it is present. Soft-tissue tumors are classified histologically on the basis of the adult tissue they resemble [9, 10]. These results are based on studies in which both bone and soft-tissue lesions were evaluated. MRI. Fat suppression on T2-weighted MR images is useful to increase lesion-to-background signal intensity differences for high-signal-intensity lesions within the marrow or fatty soft tissue [37]. Soft-tissuecomponentandlocalextension Malignant tumors often have a soft-tissue compo-nent that can extend to the scalp or to extraaxial spacesand/orthecerebralcortex. Collins MS, Koyama T, Swee RG, Inwards CY. Soft-tissue chondroma is a rare benign tumor that consists of a small nodule of cartilage without any connection to the underlying bone (2,4,14,15). Whole-body MRI may be emerging as a promising modality for the staging and surveillance of melanoma due to its lack of ionizing radiation and higher sensitivity than CT or PET for detecting lesions in the liver, spleen, bone marrow, and subcutaneous tissue.50, 51 However, whole-body MRI may be less sensitive for lymph node or pulmonary metastases. Terminology. These metastases are seen in more than 30% of patients with melanoma metastatic disease, usually in patients with Clark level IV or V disease (depth of tumor invasion into the deep dermis or through the dermis into the subcutaneous fat) and may be the only radiologic manifestation of metastases [24]. We strongly believe it is the modality of choice and also think that, when it is used in conjunction with a systematic approach, one can correctly diagnose most masses. Soler R, Rodríguez E, Remuiñán C, Santos M. J Comput Assist Tomogr. The high soft tissue contrast and spatial resolution, and the possibility of generating 3D volumetric and functional images, make Magnetic Resonance Imaging (MRI) a valuable diagnostic imaging technique in UM. 2018 Aug;97(31):e11012. This review addresses PET/MRI of bone tumors, soft-tissue sarcoma, melanoma, and lymphoma. 4A,4B). CT, MRI, and 18 F-FDG PET/CT are commonly used for staging, preoperative planning, and posttreatment assessment. Features include 4: T1: isointense to muscle; T2: heterogeneous signal with peri-lesion edema; C+: peripheral enhancement; Differential diagnosis. Zidani H, Genah I, Lae M, Bousson V, Laredo JD. J Nucl Med 2012; 53:1244. Anticancer Res. When a lesion has a nonspecific MR imaging appearance, one is ill-advised to suggest a lesion is benign or malignant solely on the basis of its MR imaging characteristics and rate or degree of enhancement. Semin Musculoskelet Radiol. In these additional planes, it is useful to use a combination of conventional T1- and T2-weighted spin-echo MR images, turbo (fast) spin-echo MR images, gradient MR images, and short tau inversion recovery (STIR) images, as the case requires. Generally, they respect fascial borders and remain within anatomic compartments until late in their course [57]. Simply stated, the purpose of a staging system is to provide a standard manner in which to readily communicate the state of a malignancy, defining the extent of the local and distant tumor. MR imaging of clear cell sarcoma (malignant melanoma of the soft parts): a multicenter correlative MRI-pathology study of 21 cases and literature review. Variation in lesion size with time or activity would be exceedingly unusual for a malignancy and suggests a process such as a ganglion or hemangioma. Soft tissue algorithm contrast-enhanced CT showed an expansile mass and irregular destruction of alveolar bone in the right side of the mandibular molar area. 2003 Dec;32(12):687-94. doi: 10.1007/s00256-003-0668-3. All 17 specimens showed positivity for HMB-45 antibody. Imaging Key Wrist Ligaments: What the Surgeon Needs the Radiologist to Know, Review.
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