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 21,692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since gonadal yolk-sac tumour in pure form or as a component of mixed germ cell tumour is in the majority of patients highly malignant, its histological recognition is of great prognostic importance. Yolk-sac tumour may assume various different histological guises, which have hitherto caused considerable terminological confusion; the present paper is aimed at correlating these morphological diversities with biochemical features which are consistent with yolk-sac differentiation. Using an enzyme-bridge immunoperoxidase technique, a series of 16 gonadal germ cell tumours with a yolk-sac component were screened for the presence of alpha-fetoprotein, alpha-1-antitrypsin, and transferrin. These proteins, normally produced by human yolk sac, were demonstrable in all the morphological patterns of yolk-sac tumour we have previously described. Six malignant non-germ cell tumours were submitted to the same investigations, and no evidence of the three protein markers was found in five; one tumour, however, an oat cell carcinoma of the bronchus, stained positively for transferrin.
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PMID:Alpha-fetoprotein, alpha-1-antitrypsin, and transferrin in gonadal yolk-sac tumours. 8 23

Maternal serum alpha-fetoprotein (MSAFP) values are used primarily but not solely to predict the occurrence of open neural tube defects in the fetus; their use for prediction of Down's syndrome is a new initiative under investigation. The test is a good one, as far as such a test can be, but it is imperfect, because false-negative and false-positive results both occur. In other words, it is not an infallible test. To use the test as effectively as is currently possible requires a program capable of supplying baseline values in sufficient number and the follow-up procedures necessary for interpretation of positive tests. In other words, it is not simply an office test. Because there is no effective treatment to relax the burden of neural tube defects in the large majority of patients, prevention of disease involves termination of pregnancy at present. In other words, use of the test is value laden and controversial for some sectors of society. Despite its imperfections, the need for an elaborate societal structure to apply it, and its value-laden context the test is considered by many as a necessary procedure to maintain normal standards of practice. Indeed, the American College of Obstetricians and Gynecologists issued a statement advising its fellows to be aware of the availability of MSAFP testing and to discuss such testing with patients. It is natural that confusion about protocol and anxiety about practice and its consequences are prevalent in this context. The American Society of Human Genetics (ASHG) offers here a statement about issues that affect MSAFP testing and the attendant pitfalls.
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PMID:Maternal serum alpha-fetoprotein screening programs and quality control for laboratories performing maternal serum and amniotic fluid alpha-fetoprotein assays: policy statement. American Society of Human Genetics. 243 25

This article describes some of the recent developments in the pathology of germ cell tumors of the testis. Many germ cell tumors show different types of differentiation. Two different explanations for this phenomenon include the differentiation of other germ cell elements from totipotential embryonal carcinoma cells or the direct differentiation of neoplasms from a malignant intratubular germ cell. Although the concept that there is a subset of seminomas having a poorer prognosis still exists, the histologic identification of such "anaplastic seminoma" remains an unachieved goal, and we, therefore, do not recommend the use of the term anaplastic seminoma at present. A recent analysis of spermatocytic seminomas has failed to demonstrate that they are capable of meiotic division. They are composed of cells differentiating in the direction of spermatocytes, but they have not achieved that stage. The prognosis, in general, remains excellent, although recently sarcomas have been reported in association with spermatocytic seminomas with metastasis of the sarcomatous elements. The presence of human chorionic gonadotropin-producing syncytiotrophoblastic giant cells in otherwise pure seminomas does not appear to adversely affect the prognosis. Yolk sac tumors have a varied histology that many pathologists do not recognize. The presence of intercellular basement membrane (parietal differentiation) is useful in the recognition of yolk sac tumor. Sometimes solid foci of yolk sac tumor may be mistaken for seminoma, and alpha-fetoprotein and cytokeratin stains may be useful in this situation, although the presence of basement membrane, hyaline globules, and focal microcysts by light microscopy may obviate the need to use them. Hepatic and enteric (or endometrioid) differentiation may occur in yolk sac tumors and cause diagnostic confusion. The development most "non-germ" cell malignancies in patients with germ cell tumors appears to occur by transformation of aneuploid teratomatous elements at the primary or metastatic site. The identification of such malignancies depends on the recognition of invasion by the elements rather than on high-grade cytologic atypia. Unusual patterns of choriocarcinoma and yolk sac tumor may be encountered following chemotherapy, and there is circumstantial evidence that some sarcomas and carcinomas occurring in patients with testis cancer may develop directly from yolk sac tumor.
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PMID:Recent developments in the pathology of germ cell tumors. 283 17

Human chorionic gonadotropin (hCG) may be used in the monitoring of early pregnancy. It may also be used as a tumor marker in the diagnosis and follow-up of gestational trophoblastic disease, choriocarcinoma and testicular carcinoma. The combination of maternal serum unconjugated estriol, alpha-fetoprotein and quantitative hCG has shown promise as an antepartum screen for Down syndrome. In the quantitative assessment of hCG, the calibrators used by various kits are standardized to one of two different standards, either the Second International Standard or the First International Reference Preparation (IRP), established by the World Health Organization in 1968 and 1975, respectively. The IRP is now considered the Third International Standard, and both terms may be used interchangeably. Confusion may exist in clinical situations if quantitative hCG levels determined by assays in different laboratories using different standards are compared or used simultaneously. Practitioners are advised to be aware of which calibration standard is utilized in their laboratory and to interpret the results accordingly.
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PMID:Measuring quantitative serum human chorionic gonadotropin. Variations in levels between kits. 765 Jun 56

A large number of ascitic fluid tests, e.g., fibronectin and cholesterol, have been proposed as helpful in detecting malignancy as the cause of ascites. Unfortunately, these "humoral tests of malignancy" are nonspecific. Although the ascitic fluid concentrations of these proteins or protein-bound substances tend to be quite high in patients with peritoneal carcinomatosis and low in the setting of cirrhotic ascites, the problem is that patients with tuberculous peritonitis, cardiac ascites, pancreatitis ascites, etc. usually have values in the malignancy range, i.e., false-positive results. This can lead to an extensive search for a nonexistent tumor, with confusion and anxiety for patient and physician. The cytology is the single best test to order when peritoneal carcinomatosis is suspected; its sensitivity approaches 100%. However, peritoneal carcinomatosis is only one of several mechanisms by which tumors can cause ascites. No one test can be expected to detect tumors as the cause of these diverse mechanisms of ascites formation. The serum-ascites albumin gradient is a helpful test in classifying ascitic fluid specimens into portal-hypertension-related and non-portal-hypertension-related categories. An elevated serum alpha-fetoprotein test can be useful in raising suspicion of hepatocellular carcinoma. Careful analysis of ascitic fluid, without measurement of "humoral tests of malignancy," combined with information obtained from the history and physical examination, usually lead to an accurate diagnosis of the cause of ascites.
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PMID:Malignancy-related ascites and ascitic fluid "humoral tests of malignancy". 818 30

A family's coping repertoire may be challenged when the result of a standard prenatal maternal serum alpha-fetoprotein screening is not within a normal range. Abnormal screening results can cause families to experience anxiety and confusion at a time when they may need to make difficult decisions. The nurse's role is to provide information and emotional support and to coordinate health care services for optimal family coping.
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PMID:Family care related to alpha-fetoprotein screening. 865 2

In a study of 130 first trimester cases of trisomy 21 and 959 controls we have shown that the median MoM for alpha-fetoprotein (AFP) is lower (0.82) and that for total human chorionic gonadotrophin (hCG) is higher (1.31) than in the control group. For AFP 15.3% of cases were below the 5th centile and for total hCG 19. 8% were above the 95th centile. The median shift observed for AFP and total hCG is poorer than that for pregnancy associated plasma protein-A (PAPP-A) or free beta-hCG and together with maternal age, AFP and total hCG could only be expected to detect 40% of cases. In combination with PAPP-A, total hCG would identify 52% of cases, somewhat less than the 67% observed with free beta-hCG and PAPP-A. However, we have demonstrated for total hCG a significant temporal change in median MoM with gestational age. Before 70 days the median MoM was less than 0.5, between 70 and 83 days this increased to 1.13, and between 84 and 97 days this increased to 1.52. This median shift has significant implications for interpreting previous studies and even more significant implications for detection rates. When population parameters specific to the gestational age in question are used, detection rates with total hCG and PAPP-A increase from 47% at 70-83 days to 60% at 84-97 days. This observation explains much of the confusion around total hCG in the first trimester and shows the importance of selecting analyte pairs and population parameters appropriate to the time in gestation when screening is performed.
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PMID:Is maternal serum total hCG a marker of trisomy 21 in the first trimester of pregnancy? 1074 Feb 4

We report 28 testicular seminomas with cystic spaces of variable nature, sometimes accompanied by solid and hollow tubular patterns (12 cases). The spaces often suggested reticular or microcystic patterns of yolk sac tumor, and the solid and hollow tubular patterns often added to the diagnostic confusion. The tumors occurred in men 21 to 55 years old and on gross examination had the typical appearance of seminoma. On microscopic examination, the spaces ranged from small, closely packed and relatively regular to dilated, more dispersed and somewhat irregular. The hollow tubules appeared to result from central discohesion within nests of tumor. The spaces, particularly when large, often contained occasional tumor cells or inflammatory cells within pale edema fluid. The cytologic appearance of the cells lining the spaces, and in the surrounding tumor, retained the typical features of seminoma cells. Thirteen tumors (46%) either lacked (8 cases) or had very scant (5 cases) lymphocytes in the cystic and tubular areas, and hyaline globules were absent. Thirteen of 13 tumors were immunopositive for OCT-3/4 in the nontypical and typical areas; 9 of 10 were placental alkaline phosphatase positive, and 7 of 10 were c-Kit (CD117) positive. The same 13 cases were negative with cytokeratin (AE1/AE3) and alpha-fetoprotein stains. Distinction from yolk sac tumor is aided by the observation that the spaces of yolk sac tumor are often more irregular in their individual shapes and frequently form anastomosing channels. Additionally, the spaces of yolk sac tumor randomly merge with various other yolk sac tumor patterns. The cells lining spaces in yolk sac tumor are often flattened with compressed nuclei and lack the typical prominent nucleoli of seminoma cells. Paucity of lymphocytes and intracystic edema, however, are not differentially helpful, although basophilic fluid favors yolk sac tumor. A panel of immunostains (AE1/AE3, OCT-3/4, and alpha-fetoprotein) is helpful in the differential with yolk sac tumor in especially problematic cases. The edema and paucity of lymphocytes may suggest spermatocytic seminoma, but the varied cell types of that neoplasm are absent.
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PMID:Seminoma with tubular, microcystic, and related patterns: a study of 28 cases of unusual morphologic variants that often cause confusion with yolk sac tumor. 1576 5

Since 1999, numerous articles have reported the generation of hepatocytes from different types of extrahepatic stem or precursor cells. This opens exciting new possibilities for pharmacology and toxicology, as well as for cell therapy. Hepatocyte marker expression, including albumin, cytokeratin 18, c-met, alpha-fetoprotein and cytochrome P450 3A4 and -2B6, has been observed after transplantation of different types of human stem cells into the liver of laboratory animals or in vitro after incubation with cytokines. These intriguing observations have prompted scientists to classify stem cell-derived cell populations as hepatocytes. However, this conclusion may be premature. It has been shown that factors of the liver microenvironment can induce expression of a limited number of hepatocyte marker genes in nonhepatic cell types. To conclude on the grounds of a limited number of markers that these cells are true hepatocytes is not indicated. In this case one should carefully evaluate crucial hepatocyte-defining enzymatic properties. The present article: i) reviews studies describing the fate of extrahepatic human stem and precursor cells in livers of laboratory animals, including the possibility of cell fusion; and ii) critically discusses the phenotype of stem cells after application of various differentiation protocols aimed at generating human hepatocytes. In addition, the necessary criteria needed for defining a true hepatocyte are suggested. Establishing the necessary properties for stem cell-derived hepatocytes is timely and reasonable, and thus avoids further misleading semantic confusion. Finally, it is essential to understand that the definition of a bona fide hepatocyte should not be limited to qualitative assays, such as reverse transcriptase polymerase chain reaction and immunohistochemistry, but has to include a quantitative analysis of enzymatic activities, which allows direct comparison with primary hepatocytes. Although the stem cell-derived-hepatocyte does not yet exist there is a good chance that this aim may be achieved in the future.
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PMID:Generation of human hepatocytes by stem cell technology: definition of the hepatocyte. 1692 53

A 17-year-old boy presented with somnolence and mental confusion. Physical examination demonstrated motor disturbances. Laboratory investigation showed elevated levels of alpha-fetoprotein in serum and cerebrospinal fluid. The CT scan revealed a heterogeneous mass at the pineal region. At the MRI, this lesion was hypointense on T1 and hyperintense on T2-weighted images, enhancing after contrast administration. The patient underwent a surgical biopsy, which defined the diagnosis of yolk sac tumor. We emphasize the correlation of neuroimaging and pathological findings of this rare pineal region tumor.
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PMID:Pineal yolk sac tumor: correlation between neuroimaging and pathological findings. 1760 29


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