Hibernoma of the left axilla; a case report and review of MR imaging

We present a case of a hibernoma arising from the left axilla in a 24-year-old woman. The imaging characteristics on both contrast-enhanced CT (attenuation similar to surrounding skeletal muscle) and T1-weighted MR imaging (signal intensity intermediate between those of skeletal muscle and subcutaneous fat) were inconsistent with a fatty mass. The diagnosis of hibernoma was only made after marginal excisional biopsy, which confirmed the presence of brown fat on histologic analysis. We briefly present the imaging findings in our case and compare the imaging characteristics of previously reported hibernomas. Although hibernomas classically contain brown fat, imaging characteristics on T1-weighted images typically demonstrate a mass that is hypointense to adjacent subcutaneous fat. Knowledge of its MR imaging characteristics may help to suggest hibernoma in the preoperative diagnosis, although other tumors should still be considered in the differential diagnosis     

Intraosseous and intradiscal gas in association with spinal infection: report of three cases

The detection of a vacuum phenomenon within the intervertebral disk usually confirms the diagnosis of degenerative disease rather than an infective process. A similar phenomenon in the vertebral body generally indicates ischemic necrosis. However, spinal infection may rarely be accompanied by intradiscal or intraosseous gas so that the latter finding does not entirely exclude the possibility of infection. Three cases are reported to illustrate gas formation in association with vertebral infection.     

Occult intraosseous fracture: magnetic resonance appearance versus age of injury

Twenty-two cases of occult intraosseous fracture in the region of the knee are presented. Occult intraosseous fractures have been incidentally detected in the magnetic resonance (MR) evaluation of the knee in the setting of a recent physical injury and normal radiographic studies. There is no unique mechanism of injury, but occult intraosseous fracture presumably results from direct impaction or axial overloading. MR shows speckled or band-like areas of low signal in the intramedullary space of the epiphyses, and occasionally, the adjacent metaphyses. In most cases, T2-weighted images show high signal in corresponding regions of variable size. The relative extent of high signal findings is shown to vary significantly with the age of injury. Individual variability within groups, however, precludes the actual prediction of lesion age on the basis of the MR appearance. Our observations provide indirect evidence that the findings on T2-weighted images resolve earlier than the corresponding findings on T1-weighted proton density images. The primary differential diagnosis in cases of occult intraosseous fracture is stress fracture. The diagnosis of occult intraosseous fracture may be important in explaining persistent pain after injury in otherwise normal knees.     

Intraosseous leptomeningeal cysts of the posterior cranial fossa.

Post-traumatic leptomeningeal cysts involving the occipital bone are intraosseous lesions which do not erode through the outer table, in contradistinction to leptomeningeal cysts elsewhere in the calvaria. In two of four reported cases, communicating hydrocephalus was associated with the intraosseous cyst. The clinical and radiological findings suggest that intraosseous leptomeningeal cyst of the posterior fossa represents a distinct entity. Resection of the cyst and closure of the dural defect may be less important than treatment of the communicating hydrocephalus.     

颅骨内异位脑膜瘤的影像学诊断

目的：复习８例原发性颅骨内脑膜瘤的ＣＴ、平片及血管造影表现，探讨其诊断条件。材料与方法：对８例经手术及病理证实的原发性颅骨内脑膜瘤的平片、血管造影及ＣＴ征象进行分析。结果：７例良性颅骨内脑膜瘤呈膨胀性生长，１例恶性颅骨内脑膜瘤呈溶骨性。６例ＣＴ平扫呈高密度，５例加增强后明显强化。５例血管造影显示４例肿瘤颈外动脉供血，１例正常。结论：良性颅骨内脑膜瘤呈膨胀性生长，恶性者呈溶骨性生长。若结合平片、血管造影及ＣＴ扫描所见，有做出异位颅骨内脑膜瘤诊断的可能性。     

Hibernomas show intense accumulation of FDG positron emission tomography

We present 2 cases of hibernoma. Positron emission tomography using the glucose analog [18F]fluoro-2-deoxy-d-glucose (FDG) of 2 patients with hibernoma showed intense accumulation. Standardized uptake values (SUVs) in these patients were 11.93 and 26.74, values much higher than the SUVs reported in published studies of liposarcomas. Standardized uptake values of FDG positron emission tomography may thus be able to differentiate hibernomas from liposarcomas.     

Giant notochordal hamartoma of intraosseous origin: a newly reported benign entity to be distinguished from chordoma. Report of two cases

Two cases are reported of a newly described intraosseous entity of vertebral bodies deemed "giant notochordal hamartoma of intraosseous origin". This entity is commonly mistaken for chordoma and must be distinguished from it as the consequences of misinterpretation may be serious. The clinical, radiological and histologic criteria that can be used to distinguish these two entities are emphasized. Included is a proposed pathogenesis for this lesion, its probable notochordal origin, and a review of other probable cases.     

骨内脂肪瘤的X线及CT表现（附6例报告并文献复习）

目的：探讨骨内脂肪瘤的X线及CT表现,提高其诊断准确率。方法：收集6例经病理证实的骨内脂肪瘤的X线及CT影像资料,结合文献对其临床、病理及影像表现进行回顾性分析。结果：6例均为单发病灶,其中1个病灶位于肩胛冈、1个病灶位于第四腰椎下关节突、3个病灶位于股骨头、1个病灶位于跟骨。X线平片表现为边界清或不清的圆形、类圆形或不规则形透亮区,可伴硬化缘。CT图像上病灶表现为圆形、类椭圆形或不规则形脂性密度区,CT值为-3 5～-110HU,其中1例病灶中央见结节状钙化,病灶最大径为1.8～2.6cm。边缘不规整,伴有厚薄不等的硬化边。结论：X线平片有助于显示骨内脂肪瘤的发生部位,而CT检查能够在术前对其做出定性诊断,从而为临床制定治疗方案提供影像学依据。     

Intraosseous lipoma of the frontal bone. A case report

Intraosseous lipomas are among the most uncommon bone tumors. They arise most often in the appendicular skeleton. There are very few reported cases of intraosseous lipomas within the skull bones. We report a case of intraosseous lipoma of the frontal bone with conventional radiography and CT findings.     

原发性颌骨骨内癌的CT表现与病理对照

目的提高对原发性颌骨骨内癌的认识.方法搜集临床、手术、病理证实的原发性颌骨骨内癌6例,回顾性分析其CT、临床和病理表现.结果5例发生于下颌骨,1例位于上颌骨.3例CT表现为筛孔状骨质破坏,周围形成软组织肿块.3例表现为大块溶骨性骨质破坏,在一侧形成巨大软组织肿块.2例为鳞癌,4例为腺癌,包括1例乳头状腺癌,1例黏液性乳头状腺癌;2例腺样囊腺癌.结论原发性颌骨骨内癌好发于下颌骨,CT表现为骨恶性肿瘤征象,在颌骨恶性肿瘤中应作为鉴别诊断考虑.     

骨内腱鞘囊肿的影像学表现

目的:探讨骨内腱鞘囊肿的影像学表现及诊断与鉴别诊断.方法:回顾性分析经手术证实的20例骨内腱鞘囊肿的临床及影像资料,均行X线、CT检查,2例行MRI检查.结果:X线、CT表现为邻近关节面的类圆形囊样透亮区,边界清晰,18例有完整硬化边,10例病灶内见粗细不均的条状骨性间隔,3个病灶通过裂隙与关节腔相通,CT值20～60 HU,MRI在T2WI和脂肪抑制序列均表现为高信号.结论:骨内腱鞘囊肿的X线、CT典型表现为骨内邻近关节面的囊状破坏,边界清晰硬化,MRI在T2WI和脂肪抑制序列均表现为高信号,结合发病部位和临床症状及影像学表现,对本病可作出正确诊断.     

A rare bone abnormality: intra-bone synovial cyst. Apropos of a case

One case of intraosseous ganglion is reported and compared with a review of the literature. The clinical findings, the physiopathological and radiological patterns are discussed as well as the differential diagnosis.     

腕关节月骨舟骨骨内腱鞘囊肿的影像学表现

目的 观察腕关节月骨、舟骨骨内腱鞘囊肿的影像特点。方法 分析经手术证实的6例共7处(月骨6处、舟骨1处)腕关节骨内腱鞘囊肿的X线(6例)、CT(4例)和MRI(1例)表现。结果 平片典型表现为月骨、舟骨小的囊变，直径为0．5cm左右。边缘光滑、清楚、硬化。6处病灶位于骨内，骨性关节面完整，囊变与关节腔不相通，1处与关节腔相通。4例CT扫描显示病灶比X线平片清楚。1例在MRT1WI表现为月骨骨内的中低信号灶，边缘硬化，T2WI为略高信号。结论 腕关节月骨、舟骨骨内腱鞘囊肿典型表现为骨内囊状破坏，边界清楚硬化。CT显示病灶比平片清楚。在MRT1WI呈中低信号，T2WI呈中高信号。     

Intraosseous venous drainage of pretibial varices

In this study, we present the case of a 74-year-old male patient who presented with a painful pretibial swelling. The patient had a history of varices of the ipsilateral leg for which he had undergone stripping and ligation. At physical examination, pretibial varices and an associated soft tissue swelling were found. Ultrasound revealed pretibial varices, one of which caused a defect on the anterior tibial cortex. Plain radiography showed a small subcortical lucency of the tibial shaft. MRI confirmed the presence of pretibial varices, one of which perforated through the anterior tibial cortex and then coursed intramedullary as an enlarged intraosseous vein. Based on these findings, the diagnosis of varices with an intraosseous venous drainage anomaly was made. The patient was subsequently successfully treated by ambulatory minisurgical phlebectomy. Knowledge and recognition of this intraosseous venous drainage anomaly, which is a rare condition, is pivotal for correct patient management. We review clinical and imaging findings, and discuss previously reported cases.     

骨内腱鞘囊肿的发病机制及临床和影像学表现研究

目的：探讨骨内腱鞘囊肿的发病机制、临床特点及影像学表现,提高对本病的认识及术前诊断与鉴别诊断能力。方法：回顾性分析经手术病理证实的28例骨内腱鞘囊肿的临床及影像学资料;28例均行x线平片、CT检查,其中16例行MRI检查。结果：28例均为单发病变,共28个病灶,其中股骨头6个,胫骨近端6个,距骨滑车6个．胫骨远端3个,腕月骨3个．股骨远端、髋臼、肱骨近端和腕舟骨各1个。病灶均位于骨内邻近关节面,病灶大小介于0．8cm×1．2cm～2．5cm×2．9cm之间。单房型25例．多房型3例。28个病灶X线平片和CT表现为圆形、类圆形或不规则形囊样低密度区,边缘清晰,均有薄层完整硬化边．相邻关节间隙无明显改变。16个病灶MRIT,wI表现为低到中等信号,TzwI表现为高信号。多房型病灶内有粗细不等的骨性间隔,MRI表现为长T-短T。信号。穿透型15例,表现为病灶通过邻关节面裂隙与关节腔相通或病灶与关节旁软组织腱鞘囊肿相连;特发型13例,表现为骨内单一病灶,骨外结构正常。结论：骨内腱鞘囊肿有其特殊发病部位,影像学表现典型,结合发病年龄和临床症状,可以作出正确的术前诊断。     

False-positive findings on 18F-FDG PET/CT: differentiation of hibernoma and malignant fatty tumor on the basis of fluctuating standardized uptake values

OBJECTIVE: Hibernoma is a benign tumor of brown fat that has imaging features similar to those of malignant fat-containing soft-tissue tumors. Hibernoma is metabolically active on (18)F-FDG PET/CT, and its presence can lead to false-positive interpretations. We present three cases in which fatty lesions with increased radiotracer uptake identified on FDG PET/CT turned out to be hibernomas. The standardized uptake values of the lesions were similar to those reported in the literature for liposarcoma. However, all three patients had variable standardized uptake values over time. CONCLUSION: Variation in standardized uptake values over time is an imaging characteristic that may be helpful for differentiating hibernoma and malignant fatty tumor.     

Hibernoma: a case report demonstrating usefulness of MR angiography in characterizing the tumor

Hibernoma is a rare, benign soft-tissue tumor composed of brown fat. In the past, there has been an extensive discussion of the CT attenuation and MRI signal characteristics of hibernomas. However, recent reports have focused upon the tumor vascularity of hibernomas. We describe the only case in the literature which utilizes state of the art contrast enhanced MR angiography to clearly characterize the surface and intratumoral vessels to help confirm the diagnosis of a hibernoma and aid in the preoperative planning.     

邻关节骨囊肿的CT、MR表现特点

目的探讨邻关节骨囊肿的影像学诊断。方法本组共36例经病理证实的邻关节骨囊肿病例,其中19例做了CT扫描检查,17例做了MRI检查,5例(5/36)同期做了CT和MRI检查。结果邻关节骨囊肿的CT上主要表现呈圆形或卵圆形的低密度病灶,边缘可见硬化,单房或多房,骨皮质可有断裂,病灶多位于关节软骨下,三维重建显示病灶与关节腔相通;MRI上主要表现呈类圆形或不规则形病灶,T1WI上为均匀的低信号,T2WI上为均匀的高信号,在STIR图像中异常信号未被抑制,病灶位于关节软骨下,增强扫描病灶边缘环形强化;病灶与关节相通。结论CT和MR是检测这类病变的重要手段。     

Intraosseous arteriovenous malformations mimicking malignant disease

Primary (congenital) intraosseous arteriovenous malformations are rare, accounting for less than one per cent of all primary intraosseous lesions. They are quite variable in their gross and microscopic presentation, yet all can be traced to anomalous development of the primitive vascular system. They may be totally asymptomatic, cosmetically disfiguring, painful, or on rare occasions, cause high-output cardiac failure. Surgical treatment is often unrewarding with recurrence not uncommon. Intra-arterial embolization has shown promising results. We present three cases of primary intraosseous arteriovenous malformations which on initial work-up mimicked malignant disease. Arteriography proved diagnostic in all three cases.