Primary neuroendocrine neoplasms occurring in the mediastinum are rare. The spectrum of such tumors can range from low- to high-grade neoplasms. The histogenesis of these tumors is varied, and some of them may originate from ectopic tissues in the mediastinum whereas others represent tumors native to the thymus. Primary thymic neuroendocrine carcinomas therefore need to be separated from other neuroendocrine neoplasms of the mediastinum, namely ectopic parathyroid tumors and paragangliomas. The histopathologic classification of primary neuroendocrine carcinomas of the mediastinum is still under debate and continues to be controversial, as is attested to by the different publications on the topic. Some authors continue to use old terms such as "carcinoid" and "atypical carcinoid" to designate these lesions, whereas others favor the use of a more unifying nomenclature that acknowledges the malignant nature of these lesions, namely that of neuroendocrine carcinoma. However, one aspect that all agree on is that, when they occur in the thymic region, these tumors should be considered as aggressive neoplasms capable of local recurrence and distant metastasis. This review will center on the morphologic spectrum of neuroendocrine carcinomas of the thymus, with special emphasis on diagnostic features and criteria for classification.
"The overall five-year survival rate in the present study was 45.5% (Table II), which is consistent with that reported in earlier studies (3,5). However, the median OS was shorter than that of previous reports (1,12,13), which may be due to more than half of the patients reported in the present study not undergoing surgery. "
[Show abstract][Hide abstract] ABSTRACT: Primary neuroendocrine tumors of the thymus are rare mediastinum tumors, which present a distinct type of tumor, which exhibit morpholgical and biological neuroendorcine features including the production of numerous biogenic amines. The aim of the present study was to evaluate factors influencing long-term survival in patients with primary neuroendocrine tumors of the thymus. A total of 22 patients exhibiting primary thymic neuroendocrine tumors, who were treated at the Zhejiang Cancer Hospital (Hangzhou, China), between 1995 and 2012 were reviewed. Survival curves were plotted using the Kaplan-Meier method and the Cox proportional hazards model was used for multivariate analysis. The overall five-year survival rate was 45.5% and the median survival time was 59 months in all of the patients. Histological grade (P<0.001), Masaoka-Koga stage (P=0.003) and surgical resection status (P=0.004) were identified to be associated with patient survival time. Furthermore, multivariate analysis identified that the histological grade was an independent prognostic factor, which was applicable to all patients (P=0.009). Therefore, the histological grade and Masaoka-Koga stage, as well as surgical resection status present three prognostic factors in patients exhibiting primary thymic neuroendocrine tumors.
"Some previous studies indicate that carcinoid tumors arising in the thymus may show a more aggressive behavior than their pulmonary counterparts.6 In recent years, attempts have been made to validate tumor grading and the range of clinical behavior.7-9 Still, however, little is known about the classification of thymic neuroendocrine tumors and their clinical behavior because of their rarity. "
[Show abstract][Hide abstract] ABSTRACT: Thymic neuroendocrine carcinomas (NECs) are uncommon, for which there is no established information available because of a limited number of epidemiological study in Asia.
We reviewed 21 cases of surgically resected thymic NECs, and evaluated their pathological and clinical features.
It showed male predominance (male/female ratio, 15/6) with wide age range from 20 to 72 years (mean age, 49 years). All 21 cases were divided into two types according to the World Health Organization criteria: atypical carcinoid (n=18) and large cell NEC (n=3). Three cases of atypical carcinoid (AC) were associated with ectopic Cushing's syndrome. All the patients (3/3) with large cell NEC (3/3) and 16.7% (3/18) of those with AC died of tumor progression. Common sites of metastasis included lung, lymph node, brain, lumbar spine, mediastinum, bone, and liver.
In conclusion, thymic neuroendocrine tumors carry a poor prognosis. Regarding the tumor classification, our results showed that a vast majority of carcinoids in the thymus correspond to ACs. In addition, our results also indicate that typical carcinoid is a very rare entity. Some cases of AC exhibited a large size, solid pattern and they showed aggressive clinical behavior, which highlights the spectrum of histologic appearances of thymic NECs.
[Show abstract][Hide abstract] ABSTRACT: Sharp-cutoff filtering characteristics require a high-order filter. For a not-too-high filter order, IIR digital filters are required. In this paper, we present two methods for designing high-order tunable bandpass passive digital filters that can provide sharp-cutoff capability for real-time filtering applications. In the first method, a tunable bandpass digital filter is obtained from a lowpass to bandpass frequency transformed digital filter. In this method, a derived expression for each of the coefficients of the second-order and the decomposed second-order passive digital filter sections is used to achieve real-time digital tuning. In the second method, a tunable bandpass digital filter is obtained by cascading a lowpass and a highpass frequency transformed digital filters. These methods provide two feasible approaches from which realtime tunable sharp-cutoff bandpass passive digital filters can be designed.
Circuits and Systems, 2002. MWSCAS-2002. The 2002 45th Midwest Symposium on; 09/2002
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