MR imaging of soft-tissue masses of the extraperitoneal spaces.

Magnetic resonance (MR) imaging has an increasing role in evaluating soft-tissue masses of the extraperitoneal spaces. Since the MR imaging features of most soft-tissue masses are nonspecific, prediction of a specific histologic diagnosis remains a challenge for the radiologist. However, there are certain specific MR imaging appearances that are helpful for more accurate diagnosis. Some histologic components, such as myxoid stroma, collagen fibers, calcification, and fat, have characteristic MR imaging features. Recognition of these features can assist the radiologist in limiting the differential diagnosis. Dynamic enhancement patterns can reflect the vascularity of masses and may be useful in diagnosis, especially in differentiating benign from malignant soft-tissue masses. Familiarity with specific signs and knowledge of diagnostic pitfalls are also important for shortening the list of differential diagnoses. Specific signs are the target sign, the bowl of fruit sign, a whorled appearance, a flow void, speckled enhancement, associated lymphadenopathy, and extension into the intervertebral foramen. Diagnostic pitfalls are as follows: a myxoid stroma simulating cystic degeneration and necrosis, collagen fibers simulating hemorrhage, a fat component simulating extraperitoneal fat, extensive intratumoral hemorrhage simulating hematoma, benign masses mimicking malignant ones, malignant masses mimicking benign ones, and peritoneal lesions mimicking extraperitoneal masses.     

Paraspinal interfaces in the lower thoracic area in children: evaluation by CT

Computed tomography was used to examine the three paraspinal interfaces (lines), consisting of the right and left paraspinal areas and the prespinal area in the lower thorax in 20 children. The abnormal CT findings were correlated with plain radiographic findings. The various disease contributing to paraspinal abnormality included malignant and benign neoplasm and inflammatory disease. Neuroblastoma was the most common entity. Fourteen of 20 patients had paraspinal masses representing either metastasis or lymphoma. Four had small pleural effusions and two had a combination of small pleural effusion and masses. Plain radiographs also showed the paraspinal masses, except in the prespinal area, where four of seven abnormalities seen with CT were not detected with plain radiographs. CT also better demonstrated the extent of involvement than did plain radiography.     

Thoracic extramedullary hematopoiesis in sickle-cell disease

The radiographic manifestations of thoracic extramedullary hematopoiesis are unilateral or bilateral, smooth, sharply delineated, often lobulated paraspinal masses without erosion of the vertebral bodies or ribs, sometimes associated with subpleural, paracostal masses. These radiographic findings were encountered in eight adult patients with homozygous sickle-cell disease. In one patient, the masses encompassed essentially the entire thoracic paravertebral area bilaterally. In the other seven patients, the masses were unilateral and limited to the region of the eighth to the 12th thoracic vertebrae. Two of the eight patients had lateral subpleural masses that were not contiguous with the paraspinal masses and that were located medial to the lateral portions of the ribs. Follow-up in seven of the cases ranged from 2 to 15 years and demonstrated, after relatively rapid growth initially, either no change in size or slow growth. Each patient was asymptomatic with regard to the thoracic masses. Histologic verification was not available in any case because of the lack of clinical indication for invasive diagnostic or therapeutic procedures. The presence of well-defined unilateral or bilateral paraspinal masses and/or paracostal masses in patients with homozygous sickle-cell disease and without related symptoms should alert one to the possibility of the presence of extramedullary hematopoiesis. These masses tend to be slow-growing and should not be subjected to aggressive diagnostic and therapeutic measures.     

Imaging and pathological correlation of soft-tissue chondroma: a serial five-case study and literature review

The imaging findings (X-ray and MRI) and patterns of calcification of five patients with pathologically proven soft-tissue chondroma were correlated with histopathology. The size ranged from 0.5 to 3 cm. Four showed calcifications: curvilinear, punctuate, mixed curvilinear, and punctuate patterns, and the other one with a dystrophic or homogenous dense pattern showed hypointensity on T1- and T2-weighted MR imaging. Histopathology showed hyaline cartilage with nests of chondrocytes in the lacunae. Soft-tissue chondroma is a rare, benign soft-tissue tumor. It should be differentiated from other soft-tissue masses, especially malignancy.     

Imaging of tumoral calcinosis: new observations

Five patients with tumoral calcinosis were evaluated with radiography, bone scintigraphy, computed tomography (CT), and magnetic resonance (MR) imaging. The arthropathy of calcium pyrophosphate dihydrate deposition disease was seen in two of the patients and pseudoxanthoma elasticum-like syndrome in three. Identification of calcific particular masses on radiographs is characteristic of tumoral calcinosis. Marrow lesions could be identified as patchy areas of calcification (calcific myelitis) in long bones and the calvarium. Bone scintigraphy appears to be the best modality for detection of the masses and marrow lesions and for monitoring therapy. At CT the masses demonstrated a varied appearance, from small and solid to large and cystic. The marrow abnormality appears as an area of increased attenuation and spotty calcification that in the skull may be associated with dural and vascular calcifications. MR imaging of the particular masses was remarkable in that the masses displayed high signal intensity on T2-weighted images despite a large calcific component. Marrow lesions also showed increased signal intensity on T2-weighted images. When calcified particular masses are present the diagnosis is rarely in question. The diagnosis may be overlooked, however, when calcific myelitis is the only manifestation.     

脊椎旁骨肉瘤的MRI表现

目的:分析原发性脊椎旁骨肉瘤的MRI表现,探讨有关的临床特点和鉴别诊断。方法:回顾性分析6例经手术与病理证实的原发性脊椎旁骨肉瘤病例,其中男2例,女4例,平均年龄35.83岁;颈椎旁1例,胸腰段旁4例,骶椎旁1例。结果:6例原发性脊椎旁骨肉瘤表现为脊椎旁类圆形或肾形不均质异常信号,其内可见囊变、坏死及大片状钙化,呈轻~中度强化,大小4.1~13.4 cm,平均8.19 cm。椎体骨质受累3例,表现为椎体后部成骨性破坏;附件受累5例,椎管受累4例,均未合并脊椎病理性骨折及椎间盘改变。结论:原发性脊椎旁骨肉瘤是一种特殊类型的骨旁骨肉瘤,其MRI表现具有一定的特征性,但是应与脊椎结核、骨母细胞瘤、软骨肉瘤及神经鞘瘤鉴别。     

Castleman病的CT表现及临床病理特点

目的：探讨Castleman病（CD）患者的临床病理特征、CT表现特点及预后。方法：回顾性分析经手术或活检病理证实并行CT检查的24例CD患者的CT资料和临床资料,并将CT影像表现与病理结果进行对照,分析其CT表现特点。结果：24例中透明血管型15例,浆细胞型8例,混合型1例。15例透明血管型CD临床分型均为单中心型,包括胸部7例、颈部4例、腹膜后2例、盆腔及腹股沟2例,8例浆细胞型CD均为多中心型。透明血管型CD CT表现为边界清楚的软组织密度肿块,内部可见斑点状、分叉状钙化及灶状或条状低密度区;增强后动脉期肿块即明显强化,延迟期仍有强化。3例肿瘤周围见丰富的强化血管影。浆细胞型CD CT表现多发淋巴结肿大,密度均匀,增强后亦明显强化,但较透明血管型强化程度低。透明血管型CD术后均无复发,而浆细胞型CD预后多种多样。结论：CD的CT表现与临床类型、病理分型密切相关。CT对透明血管型CD的诊断具有较高的准确性,尤其是肿瘤内部的钙化及增强CT表现具有重要诊断价值,手术治疗效果好,预后佳;而浆细胞型CD缺乏特征性,确诊需要结合病理学,且预后差。     

From the archives of the AFIP. Mediastinal germ cell tumors: radiologic and pathologic correlation.

Germ cell tumors occur most frequently in the gonad but can rarely occur in extragonadal locations, usually in or near the midline. The most common extragonadal site of primary germ cell tumors is the anterior mediastinum. The most common histologic type of mediastinal germ cell tumor is mature teratoma, which is typically asymptomatic and incidentally discovered. Radiographically, these tumors appear as rounded, often lobulated masses; calcification may be seen. Imaging studies of mature teratoma frequently demonstrate cystic components and may demonstrate fat or calcium. Malignant germ cell tumors usually occur as large masses in symptomatic young male patients. Seminomas are typically of homogeneous soft-tissue attenuation, and nonseminomatous malignant germ cell tumors are typically of heterogeneous attenuation on computed tomographic scans. Therapy varies according to cell type and may include surgery, radiation therapy, or chemotherapy. Prognosis is excellent for patients with mature teratoma, good for patients with pure seminoma, and poor for patients with nonseminomatous malignant germ cell tumors and mixed germ cell tumors.     

腹膜后神经源性肿瘤的CT诊断

目的 分析30例腹膜后神经源性肿瘤的CT表现,以加深对其认识。资料与方法 30例均经病理证实。使用Siemens Plus 4A CT扫描仪。全部病例均进行了CT平扫和增强扫描。结果 （1）良性肿瘤16例,恶性肿瘤14例。位于肾上腺者19例,位于交感神经链上11例。（2）肿块不规则形14例。类圆形16例;边缘清楚25例,边缘模糊5例。（3）成神经细胞瘤和神经节成神经细胞瘤CT表现具有特征：平扫与肾脏呈等密度为主的混杂密度,增强扫描呈不均匀强化;均有较粗大无定形钙化伴有血管的包埋及腹膜后淋巴结肿大。其他病理类型的神经源性肿瘤CT表现的特征性没有前者明显。结论 大多数腹膜后神经源性肿瘤可根据其CT表现、好发于肾上腺及沿椎旁交感神经链分布的特点,结合患者发病年龄和临床资料CT可作出诊断。     

Radiographic findings in the hands in patients with systemic lupus erythematosus

Hand radiographs of 59 patients with systemic lupus erythematosus (SLE) were examined. Thirty-four revealed radiographic abnormalities, most commonly periarticular soft-tissue swelling or demineralization. Alignment abnormalities, acral sclerosis, avascular necrosis, soft-tissue calcification and terminal tuft resorption were also seen. All patients with periarticular calcification or terminal tuft resorption had Raynaud's phenomenon. Clinical indicators of disease activity (including low serum complement levels) did not correlate with the presence or severity of radiographic abnormalities. Patients with abnormal radiographs generally were older at the time of diagnosis than those with normal studies.     

Diffuse soft tissue calcification in tumoral calcinosis

Tumoral calcinosis is a rare disease characterized biochemically by hyperphosphatemia, normocalcemia, and reduced fractional excretion of phosphate. Radiographically, it has been defined by the presence of large, amorphous juxtaarticular calcific deposits. A 53-year-old woman with tumoral calcinosis was found to have unusual diffuse soft tissue calcification indistinguishable from that usually seen in collagen vascular disease and previously referred to as calcinosis universalis. It is suggested that tumoral calcinosis is a misnomer as the calcification seen in patients with this disease may be tumoral or diffuse.     

The renal parenchymal stone: a benign calcified renal mass

Five patients are described, each with a densely calcified solitary mass in a peripheral location in the kidney. There was exophytic projection of the calcification in 4 cases. Three lesions were so completely calcified as to be regarded as stones. The bulk of the lesion was calcified in the 2 other cases, in which the noncalcified portion was either avascular or hypovascular. In no case was there evidence of a soft-tissue mass extending beyond the confines of the calcification. Pathologic correlation in 1 case showed only calcification in association with some renal scarring, and in a second case demonstrated an old organized and calcified abscess. Long-term follow-up in the other 3 cases has demonstrated complete stability without evidence of tumor. All cases are believed to represent examples of calcified renal parenchymal scars, resulting from old granulomatous disease, renal abscess, or hematoma. We propose that these lesions be regarded as solitary renal parenchymal stones without malignant potential, rather than calcified masses. The significance of the findings for patient management are discussed.     

The renal parenchymal stone: A benign calcified renal mass

Five patients are described, each with a densely calcified solitary mass in a peripheral location in the kidney. There was exophytic projection of the calcification in 4 cases. Three lesions were so completely calcified as to be regarded as stones. The bulk of the lesion was calcified in the 2 other cases, in which the noncalcified portion was either avascular or hypovascular. In no case was there evidence of a soft-tissue mass extending beyond the confines of the calcification. Pathologic correlation in 1 case showed only calcification in association with some renal scarring, and in a second case demonstrated an old organized and calcified abscess. Long-term follow-up in the other 3 cases has demonstrated complete stability without evidence of tumor. All cases are believed to represent examples of calcified renal parenchymal scars, resulting from old granulomatous disease, renal abscess, or hematoma. We propose that these lesions be regarded as solitary renal parenchymal stones without malignant potential, rather than calcified masses. The significance of the findings for patient management are discussed.     

Computed tomography of soft-tissue lesions of the extremities, pelvic and shoulder girdles: sonographic and pathological correlations

Sixty-five patients with various soft-tissue tumours were examined by computed tomography (CT) and ultrasonography. Results were correlated with pathological findings. Although an accurate histological prediction could not be made in most cases, certain patterns appeared to be characteristic of specific types of tumours. A lipoma of uniformly low density may be differentiated from the heterogeneously denser liposarcoma. Multiple irregular linear densities with calcification are characteristic of haemangioma. An echo-free mass on the sonogram with soft-tissue density on CT suggests lymphoma or certain sarcomas. Small isodense subcutaneous lipomas or intramuscular lymphomatous masses may be clearly delineated on sonogram but not seen on CT. Our study indicates that the combined use of CT and ultrasound gives a very detailed basis for planning the surgical approach to the tumour.     

Soft-tissue tumors: MR imaging

We evaluated the suspected soft-tissue masses of 33 patients using magnetic resonance (MR) imaging. Thirty-two masses were defined, of which ten were malignant and 22 were benign. Specific characteristics that would allow us to distinguish the benign lesions from the malignant ones could not be identified on MR imaging. Lesions located within muscles or in the intramuscular septa were best seen with T2-weighted imaging sequences; those located within the subcutaneous fat were best outlined with T1-weighted imaging sequences. Both imaging sequences were necessary to provide the complete representation of the extent of the mass. We performed comparison studies using computed tomography (CT) in 24 of the cases. Of 92 possible comparisons and in four categories MR imaging yielded results that were superior to those obtained by CT scanning in 30 instances, equaled the results obtained by CT scanning in 62 instances, but never yielded results inferior to those obtained by CT scanning. However, MR imaging failed to demonstrate soft-tissue calcification and soft-tissue gas in one case each.     

骨原始神经外胚叶肿瘤影像学表现

目的研究骨原始神经外胚叶肿瘤的影像学特点。资料与方法搜集5例骨原始神经外胚叶肿瘤的影像及临床、手术病理资料,分析其影像学表现。结果5例中．胸椎2例,胸壁、股骨、胫骨各1例。1例胸壁病变表现为巨大软组织肿块,并推移周围组织。2例脊椎病变破坏椎管内外骨质及软组织。2例四肢长骨病变呈溶骨性骨质破坏,1例有软组织肿块。5例均未见病变内钙化及局部淋巴结肿大。MRI对显示病变组织成分及侵袭范围较X线和CT好。结论溶骨性骨破坏和巨大软组织肿块是骨原始神经外胚叶肿瘤的常见影像学表现,病灶内钙化和局部淋巴结肿大少见。MR／对显示病变组织成分及侵袭范围较好。本病最终诊断依靠病理和免疫组织化学检查。     

Calcification in cystic renal masses: is it important in diagnosis?

PURPOSE: To determine whether the presence of calcifications in cystic renal masses is important in diagnosis and to suggest an approach to the management of calcified cystic renal masses. MATERIALS AND METHODS: Eighty-one cystic renal masses containing calcification in a wall or septum were evaluated by means of review of computed tomographic (CT) images (n = 81), follow-up CT images (n = 28), and results of pathologic examination (n = 40) by the authors in consensus. Images were evaluated for lesion size, amount and morphology of calcification, and any association of calcification with soft-tissue structures. Lesions were categorized according to the Bosniak cyst classification system; the amount of calcification was determined with a subjective grading system. Progression of calcification was qualitatively determined with available follow-up CT scans. RESULTS: Twenty-one lesions were Bosniak category II (benign) and showed small amounts and thin strands of calcification. Nineteen lesions containing more extensive calcification but no enhancing tissue were category IIF. Follow-up CT results available for 16 of these lesions (average follow-up length, 5 years 8 months) showed no substantial change. The three remaining lesions were proved benign at surgery. Twenty-five lesions were category III; surgical intervention was performed in 21 of these (benign, n = 12; malignant, n = 9). Sixteen lesions that contained obvious areas of enhancing soft tissue were category IV and proved malignant at surgery. CONCLUSION: Calcification in a cystic renal mass is not as important in diagnosis as is the presence of associated enhancing soft-tissue elements. This information should enable a reasonable approach to the management of calcium-containing renal cystic lesions.     

The radiologic manifestations of alveolar soft-part sarcoma

Alveolar soft-part sarcoma is a rare soft-tissue tumor of unknown cellular origin that is characterized histologically by its organized "pseudoalveolar" pattern. The radiologic findings in 11 patients with this neoplasm were reviewed. The six men and five women were 16-48 years old (mean, 27 years). Nine patients had untreated primary tumors (thigh, four; forearm, two; and buttock, rectus abdominis muscle, and infratemporal fossa, one each) and two had locally recurrent masses (one each in the retroperitoneum and retrocrural space). All patients were evaluated by conventional radiography, two by sonography, eight by CT, five by angiography, and three by MR. Conventional radiographs showed the soft-tissue mass in only four patients; four lesions caused destruction of adjacent bone and two had soft-tissue calcification. Unenhanced CT showed low-attenuation lesions in four of five patients. The lesions were hypervascular on contrast-enhanced CT or angiography in each of nine patients studied. Prominent draining veins were shown by CT or angiography in five patients. Three lesions had a prolonged capillary stain on angiography. Alveolar soft-part sarcoma should be considered in the differential diagnosis of a hypervascular soft-tissue mass, particularly in the thigh of a young adult.     

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.     

Imaging of chest wall disorders.

Pathologic processes that may involve the chest wall include congenital and developmental anomalies, inflammatory and infectious diseases, and soft-tissue and bone tumors. Many of these processes have characteristic radiologic appearances that allow definitive diagnosis. Sternal deformities can be visualized at radiography and their severity quantified with computed tomography (CT). In cervical rib, CT with multiplanar reconstruction may demonstrate relevant anatomic detail and the relationship between bone deformity and arterial compression. In Poland syndrome, radiography reveals an area of hyperlucency on the affected side, whereas CT demonstrates the absence of the greater pectoral muscle and clearly depicts associated musculoskeletal anomalies. Tuberculosis typically manifests at radiography and CT as osseous and cartilaginous destruction and soft-tissue masses with calcification and rim enhancement. Aspergillosis involving the chest wall manifests as pulmonary consolidations and permeative osteolytic changes of the rib and spine at CT and as an area of increased signal intensity at T2-weighted magnetic resonance (MR) imaging. Neurogenic tumors and hemangiomas also typically have high signal intensity at T2-weighted MR imaging. Apparent mass extension or unequivocal bone destruction seen at CT or MR imaging may indicate chest wall involvement by lymphoma. Radiologically, soft-tissue sarcomas typically appear as areas of soft-tissue density or attenuation, often associated with necrotic areas of low density or attenuation. At radiography, plasmacytoma typically manifests as well-defined, "punched-out" lytic lesions with associated extrapleural soft-tissue masses. Chondrosarcoma frequently appears as a large, lobulated excrescent mass arising from a rib with scattered flocculent calcifications characteristic of its cartilaginous mix. Familiarity with these radiologic features facilitates accurate diagnosis and optimal patient treatment.