原发性胸椎原始神经外胚层肿瘤的动态增强MRI表现

目的 初步探讨原始神经外胚层肿瘤(PNET)的动态增强MRI表现，以及对其诊断及鉴别诊断的价值。方法 用动态增强MRI方法对已手术和病理证实的2例胸椎PNET行3次MR检查并进行前瞻性研究。结果 在信号强度-时间和对比增强率．时间曲线上，2例PNET3次检查均表现为快升慢降型，即肿瘤早期就开始迅速增强，上升峰极陡，60～120s即达到高峰水平，然后保持平坦，3．5min内未见明显下降曲线。结论 动态增强MRI扫描能帮助对PNET进行早期诊断和鉴别诊断，从而为临床选择治疗方案及估计预后提供较为可靠的依据。     

Adult primitive neuroectodermal tumor: proton MR spectroscopic findings with possible application for differential diagnosis

PURPOSE: To assess the utility of proton magnetic resonance (MR) spectroscopy in the clinical categorization of primitive neuroectodermal tumors (PNETs) in adults. MATERIALS AND METHODS: In vivo proton MR spectroscopy was performed with an echo time of 136 msec in nine adults with PNET, and findings were retrospectively compared with spectroscopic findings of 22 meningiomas, 12 low-grade astrocytomas, eight anaplastic astrocytomas, 23 glioblastomas, and 21 metastases. Nine resonances were semiquantitatively evaluated. Statistical analysis was performed by using Kruskal-Wallis and Mann-Whitney U tests. The Hochberg correction was applied for multiple comparisons. Results were prospectively validated in 24 tumors of the six types included in the study. RESULTS: The resonances of choice for identifying PNET were alanine (P <.001) and glutamate and glutamine (P =.004), both decreased with respect to meningioma; choline increased with respect to low-grade (P <.001) and anaplastic astrocytoma (P =.055); and lipids at 1.30 ppm decreased and choline and other trimethyl-amine-containing compounds increased with respect to glioblastoma (P <.001 and P =.004, respectively) and metastasis (P <.001 and P =.021, respectively). We developed an algorithm for bilateral differential diagnosis between PNET and other tumor types. The leave-one-out method was used to test the five possible differential situations in the retrospective data set, with the following results: PNET versus meningioma, 31/23/5/3 (number of total/correct/unclassifiable/incorrect procedures); PNET versus low-grade astrocytoma, 21/19/2/0; PNET versus anaplastic astrocytoma, 17/6/9/2; PNET versus glioblastoma, 32/28/2/2; and PNET versus metastasis, 30/27/1/2. In total, 131 consecutive procedures produced 103 (79%) correct classifications and nine (7%) misclassifications. Twenty-five (78%) of 32 possible procedures in the prospective independent test set produced correct classifications and four (13%) produced incorrect classifications. CONCLUSION: In vivo proton MR spectroscopy provides useful information in clinical differentiation between PNETs and common brain tumors in adults.     

Diffusion-weighted imaging and fluid attenuated inversion recovery imaging in the evaluation of primitive neuroectodermal tumors

The aim of our study was to determine whether fluid-attenuated inversion recovery (FLAIR) imaging and diffusion-weighted imaging (DWI) would be helpful in characterizing primitive neuroectodermal tumors (PNET) from other pediatric brain tumors. We expected that the compact cellular nature and the relatively small extracellular space of this tumor would affect the signal intensity on both pulse sequences relative to the more sparsely cellular glial tumors that have larger extracellular spaces. Eighteen pediatric patients with PNET were examined on a 1.5 T MRI with routine imaging plus FLAIR and compared with 28 patients with non-PNET. DWI was also performed in 7 PNET and 18 non-PNET. Seventy-eight percent of PNET were isointense to gray matter on FLAIR while 82 % of non-PNET were hyperintense and only one was isointense (3 %). Diffusion was abnormally restricted in all 7 PNET examined (100 %) but was restricted in non-PNET in only 1 out of 18 (6 %) patients who had DWI. The differences in the histologic architecture between PNET and non-PNET are reflected in both FLAIR imaging and in DWI. Received: 3 February 2001/Accepted: 13 February 2001     

Thoracoabdominal peripheral primitive neuroectodermal tumors in childhood: radiological features

Peripheral primitive neuroectodermal tumors (PNET) are extremely uncommon, malignant neoplasms affecting mostly children and young adults. We retrospectively reviewed the clinical data and radiological studies of four such cases. All cases were pathologically proven. Plain films, US, and CT scans were used. The youngest child had a huge pelvic tumor and two adolescents each had a chest wall (Askin) tumor. The fourth patient had a most unusual location of the PNET in the anterior mediastinum. The CT findings are emphasized. We emphasize that the markedly abnormal CT findings are not specific for PNET. Received: 13 February 1999; Revised: 2 July 1999; Accepted: 9 February 2000     

FDG PET scan in a primitive neuroectodermal tumor

Primitive peripheral neuroectodermal tumor (PNET) is a rare tumor that often arises in soft tissue. Magnetic resonance imaging is a good diagnostic tool that can establish the extent of disease. The utility of positron emission tomography (PET) using F-18-fluoro-2-deoxy-D-glucose (FDG) in the diagnostic work-up and staging of PNET has not been well established. We present a case of PNET of the right upper extremity that did not show FDG uptake despite its large size and aggressive nature.     

骨原始神经外胚层肿瘤（2例报告并文献复习）

目的；提高对骨原始神经外胚层肿瘤的认识。材料与方法：对２例骨原始神经外胚层肿瘤的临床表现、影像特征进行描述，并结合文献分析。结果：（１）骨原始神经外胚层肿瘤来源于神经嵴的胚胎迁移细胞。（２）多见于儿童和青少年，发病部位以胸部最常见，其余部位还有骨盆，四肢等。（３）影像表现一般呈溶骨性骨折破坏伴有软组织肿块，多有囊变，少见瘤骨和钙化。（４）Ｅｗｉｎｇ‘ｓ瘤与骨原始神经外胚层肿瘤在组织学起源上是相关性     

Primitive neuroectodermal kidney tumour

Renal primitive neuroectodermal tumour (PNET) is a rare malignant tumour of paediatric patients. We describe the important imaging findings, including the ultrasound, CT and MRI of a case of renal PNET in a teenager. To our knowledge, some findings have not been described previously. Some features that have been considered as characteristic are not present in our case, and it is, to our knowledge, the first documented case with such extensive tumour thrombus. We also demonstrate the importance of including PNET as a differential diagnosis because combined chemotherapy is thought to be the best first-line treatment in most cases. Histological diagnosis can be determined by a minimally invasive procedure instead of laparotomy or open biopsy.     

Primary Primitive Neuroectodermal Tumor of the Breast: a Case Report

Primary primitive neuroectodermal tumors (PNET) are rare malignant tumors, affecting mostly children and adolescents. Only three cases of primary breast PNETs have been reported in the medical literature, with none in Korea. We present a case of a primary PNET of the breast in a 33-year-old woman, with imaging and immunohistopathology findings.     

Osteosarcoma of the femur mimicking Ewing sarcoma/primitive neuroectodermal tumour on biopsy and metastatic carcinoma on resection

Osteosarcoma (OS) is known to have several morphological appearances, small cell osteosarcoma and epithelioid osteosarcoma being two well recognized patterns. The former can be mistaken for a Ewing sarcoma/primitive neuroectodermal tumour (ES/PNET), whereas the latter mimics metastatic carcinoma. Herein we present an osteosarcoma in a 17-year-old girl that was diagnosed as an ES/PNET on biopsy; however, the resected specimen revealed a very unusual morphology mimicking a metastatic carcinoma with a sex cord stromal tumour-like pattern.     

Primitive neuroectodermal tumour of the prostate gland: ultrasound and MRI findings

We report a rare case of primitive neuroectodermal tumour (PNET) of the prostate occurring in a 26-year-old man with a mass replacing the prostate gland in the absence of any lesion involving the bone and soft tissues. To our knowledge, there is no radiological literature that has described the imaging findings in a case of PNET of the prostate. Imaging findings in cases of PNET of the kidney are described in the literature. On ultrasound, the mass appeared multilobulated and multinodular with intratumoural heterogeneity. No brightly reflective echoes with posterior acoustic shadowing to suggest calcification were noted. MRI revealed a heterogeneous lobulated mass with irregular septae within. The mass showed low signal intensity on T(1) weighted images and appeared heterogeneous on T(2) weighted images. Haemorrhage and necrosis were also seen in the tumour.     

Breast and lung metastasis from pancreatic neuroendocrine carcinoma

Pancreatic neuroendocrine tumors(PNETs) are an uncommon malignancy,accounting for a small percentage of all pancreatic malignancies.Due to their insidious course,most PNETs present with metastatic disease.Although reports in the literature describe PNET metastasis to the liver,lung and brain,to date there are no reports of stage Ⅳ disease involving the breast.Moreover,the lack of consensus regarding classification and treatment of this entity leaves practitioners without standards of practice or a firm base from which to formulate prognosis.In this report,the case of a previously healthy 51-year-old woman with stage Ⅳ PNET is examined.After combined neoadjuvant therapy with 5-fluorouracil,carboplatin,etoposide and radiation,surgical resection revealed metastatic PNET to the breast and lung,with no microscopic evidence of residual disease within the pancreas.An extensive analysis of the presentation,diagnosis,imaging modalities,treatment options,and prognosis is included in the discussion.As demonstrated by our review,there is a need for further studies to delineate inconclusive evidence with respect to subtype classification,treatment and prognosis of PNETs.     

中枢性原始神经外胚层肿瘤的CT和MRI表现

目的探讨中枢性原始神经外胚层肿瘤(primitive neuroectodermal tumor,PNET)的影像表现特征,以提高对此病的认识。方法回顾性分析经手术病理证实的9例PNET患者的CT和MRI资料。结果发生于大脑半球7例,脑干及松果体区各1例。9例病灶边界均清晰,密度或信号不均匀。CT平扫实质部分与脑灰质等或稍高密度,MRI上T1WI呈与脑灰质等或稍低信号,T2WI呈等或稍高信号。7例无或轻度瘤周水肿;6例有明显占位效应;瘤内出血6例,钙化5例;6例见流空血管信号穿行,6例与侧脑室关系密切。5例与局部硬脑膜相连,其中2例邻近骨质变薄,增强扫描多明显强化。结论 PNET影像学表现有一定特征性。     

Primitive neuroectodermal tumour in a 60-year-old man: a case report and literature review

Primitive neuroectodermal tumour (PNET) is very rare, especially in adults. We report a 60-year-old man presented with a PNET. The symptoms at the time of diagnosis were intense headache, Broca's aphasia and right hemiparesis. Only an open biopsy was performed. Irradiation of the primary tumour was the main treatment (total tumour dose 59.8 Gy) because of serious haematological side effects due to chemotherapy. The patient tolerated radiation therapy extremely well and his neurological symptoms were improved. 1 month after completion of radiotherapy, MRI showed no regression of the tumour. Clinical deterioration was observed 10 months after the initial diagnosis and the patient died 2 months later. In cases of PNET, initial therapy is surgical bulk reduction whenever possible. Irradiation of the cerebrospinal axis is justified as a routine treatment but, owing to the radioresistance of the tumour, the addition of multiregimen chemotherapy appears to improve survival, according to the literature.     

Peripheral primitive neuroectodermal tumor of the kidney presenting with pulmonary tumor embolism: A case report

Peripheral primitive neuroectodermal tumor (PNET) of the kidney is a rare, aggressive tumor known for its recurrence and metastatic potential. Despite the frequency of venous extension to the renal veins and inferior vena cava, pulmonary tumor embolism at the initial presentation is not common. We report a case of 22-year-old female with PNET of the kidney who presented with tumor embolism in the inferior vena cava (IVC) and bilateral pulmonary artery. The patient underwent surgical resection and histopathological analysis confirmed the presence of tumor within the IVC and pulmonary arteries. The patient received adjuvant chemotherapy and is currently doing well on follow-up.     

Pancreatic neuroendocrine tumour (PNET): Staging accuracy of MDCT and its diagnostic performance for the differentiation of PNET with uncommon CT findings from pancreatic adenocarcinoma

Purpose

To investigate staging accuracy of multidetector CT (MDCT) for pancreatic neuroendocrine tumour (PNET) and diagnostic performance for differentiation of PNET from pancreatic adenocarcinoma.

Material and methods

We included 109 patients with surgically proven PNET (NETG1?=?66, NETG2?=?31, NEC?=?12) who underwent MDCT. Two reviewers assessed stage and presence of predefined CT findings. We analysed the relationship between CT findings and tumour grade. Using PNETs with uncommon findings, we also estimated the possibility of PNET or adenocarcinoma.

Results

Accuracy for T stage was 85–88 % and N-metastasis was 83–89 %. Common findings included well circumscribed, homogeneously enhanced, hypervascular mass, common in lower grade tumours (p?<?0.05). Uncommon findings included ill-defined, heterogeneously enhanced, hypovascular mass and duct dilation, common in higher grade tumours (p?<?0.05). Using 31 PNETs with uncommon findings, diagnostic performance for differentiation from adenocarcinoma was 0.760–0.806. Duct dilatation was an independent predictor for adenocarcinoma (Exp(B)?=?4.569). PNETs with uncommon findings were associated with significantly worse survival versus PNET with common findings (62.7 vs. 95.7 months, p?<?0.001).

Conclusion

MDCT is useful for preoperative evaluation of PNET; it not only accurately depicts the tumour stage but also prediction of tumour grade, because uncommon findings were more common in higher grade tumours.

Key Points

? CT accurately depicts the T stage and node metastasis of PNET. ? Uncommon findings were more common in higher grade tumours. ? CT information may be beneficial for optimal therapeutic planning.

     

Imaging of peripheral PNET: common and uncommon locations

AIM: We present the imaging features of peripheral primitive neuroectodermal tumour (PNET) in eight children, highlighting the unusual locations of this tumour in three children. MATERIALS AND METHODS: At presentation, the tumours were studied with magnetic resonance imaging (MRI; n = 6), computed tomography (CT; n = 7) and ultrasound (US; n = 1). The diagnoses were confirmed histologically (n = 8), immunohistochemically (n = 8), by cytogenetics (n = 3) and electron microscopy (n = 1). Correlation with gross pathology, histology, treatment and outcome were obtained. RESULTS: The tumours were located in the chest wall (n = 2), shoulder, pelvis, small bowel mesentery, adrenal gland, dura mater and skin and subcutaneous tissue of the abdominal wall (n = 1 each). Peripheral PNET arising from the small bowel mesentery, adrenal gland and dura mater have not been previously reported in the English literature. The tumours were mainly large (mean size: 10.6 cm) and infiltrative. All tumours were heterogeneously hyperintense on T2-weighted MRI, heterogeneously iso/hypodense on CT and had variable contrast enhancement. Most tumours were heterogeneously hypointense to muscle on T1-weighted MRI. US showed a hypoechoic mass with a cystic component. CONCLUSION: Peripheral PNET can occur in unusual locations. The clinical and imaging features of peripheral PNET are non-specific, making tissue diagnosis essential. PNET should be included in the differential diagnosis of aggressive soft tissue tumours in children.     

Primary cutaneous Ewing’s sarcoma/primitive neuroectodermal tumor manifesting numerous small and huge ulcerated masses: its complete remission by chemotherapy and magnetic resonance imaging findings

Extraskeletal Ewing’s sarcoma (ES) and primitive neuroectodermal tumor (PNET) are widely regarded as clinically and histologically identical tumors which consist of small blue round cells. Extraskeletal ESs/PNETs usually occur in the deep soft tissues of the paraspinal region, chest wall, or lower extremities. However, superficially located cases, so-called cutaneous ESs/PNETs, are exceedingly rare, and the vast majority of the reported cases present as a single small mass. We present magnetic resonance imaging (MRI) findings and clinical course of a unique case of primary cutaneous ES/PNET presenting as numerous huge masses with severe ulceration on them.     

Primary pulmonary primitive neuroectodermal tumor: CT and skeletal scintigraphic image features with pathologic correlation (2006: 6b)

We describe a rare case of a primitive neuroectodermal tumor (PNET) originating in the lung of a 28-year-old woman. A lung mass was detected incidentally on a chest radiograph taken before a Caesarian delivery. The chest P-A view showed a well-defined, lobulated mass in the right lower lobe with a small pleural effusion on the right. A thoracic CT with contrast enhancement showed a lobulated, heterogeneous, enhanced mass of approximately 9.2 × 8.4 × 6.3 cm with inner amorphous calcifications in the right lower lobe and a small right pleural effusion. A right lower lobectomy was performed 1 month after delivery. The pathology report was a primary pulmonary PNET with focal visceral pleural involvement.     

Malignant round cell tumours of bone: atypical clinical and imaging features

Objective.To describe the clinical, radiological and MRI features of six atypical cases of histologically proven appendicular Ewing sarcoma/ primitive neuroectodermal tumour (PNET). Design. Retrospective review of case notes and available imaging was carried out. Patients. Six patients (4 male, 2 female; mean age 27years, range 19–44 years), presenting over a 77-month period, were identified from the Bone Tumour Register. All had unusual clinical and imaging features for Ewing sarcoma/PNET. Results and conclusions. Four tumours were centred on the distal femoral metaphysis, one in the proximal tibial metaphysis and one in the distal tibial metaphysis. Plain radiographs were available in four cases and showed minor cortical changes. MRI demonstrated a relatively small, eccentrically located intraosseous component with a large, eccentric extraosseous component. Extension into the epiphysis was seen in three cases and into the adjacent joint in two cases. Intraosseous ”skip” metastases were present in three cases. The clinical and imaging features were atypical for conventional intraosseous Ewing sarcoma/PNET and the exact site of origin (intraosseous, periosteal or soft-tissue) was unclear. Received: 6 December 1999 Revision requested: 7 February 2000 Revision received: 20 July 2000 Accepted: 4 August 2000