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K Yamao

Publications and source records attributed to K Yamao.

66 records · Page 4Linked to original sources

[Early diagnosis of pancreatic cancer: re-evaluation of endoscopic retrograde cholangiopancreatography].

Of the 215 pancreatic ductal cancer patients for these 13 years, 154 cases undergoing ERCP were analysed. ERPs of the pancreatic cancers were classified into 4 types. 1) stenosis of the main pancreatic duct (M.P. D.) 2) obstruction of the M.P.D. 3) dilatation of the M.P.D. 4) abnormal pancreatic field (normal caliber of the M.P.D.) Most of the pancreatic cancers belonged to type 1) or 2). 7 cases were small pancreatic cancers less than 2 cm in diameter. Its pancreatograms showed type 1) or 2) and almost the same as the advanced ones. So it was easy to detect these types even in early stage. But there were a few small pancreatic cancers of which the pancreatogram showed type 4), and these cases were difficult to detect by other imaging modalities (U.S. or C.T.). Even these were easy to detect by ERCP. ERCP is the most potent diagnostic modality for an early pancreatic cancers.

Cholangiopancreatography, Endoscopic Retrograde↗

Endolumenal ultrasonography in the diagnosis of pancreatic diseases.

We evaluated the usefulness and limitations of endoscopic ultrasonography (EUS) in pancreatic mass lesions. EUS was useful in detecting small pancreatic mass lesions, especially ductal adenocarcinomas smaller than 20 mm and small islet cell tumors smaller than 10 mm. In some of these cases, characteristic echo patterns were specific and useful for differential diagnosis from focal pancreatitis. However, when EUS did not clearly delineate a tumor at the stenotic area of the main pancreatic duct, transpapillary pancreatoscopy and biopsy/cytology were sometimes effective to obtain a definitive diagnosis. EUS fine-needle aspiration should be performed in conjunction with imaging modalities when the differential diagnosis of a pancreatic mass is difficult to make. Although the value of EUS in cancer staging was overestimated, EUS in conjunction with spiral computed tomography or magnetic resonance imaging should be performed for such a purpose. Usefulness and limitations of intraductal ultrasonography (IDUS) also were evaluated. IDUS was useful in detecting carcinoma in situ and small tumors and in assessing parenchymal invasion and the intraductal spread of the tumor. IDUS was also useful in accurately localizing islet cell tumor and in differentiating benign from malignant cases of localized stenosis of the main pancreatic duct. Thus, EUS and IDUS are indispensable modalities in the diagnosis of pancreatic diseases.

Adenoma, Islet Cell↗

Endoscopic ultrasonography in diagnosis of the extent of gallbladder carcinoma.

Endoscopic ultrasonography (EUS) was performed preoperatively in 39 patients with gallbladder carcinoma. Diagnosis of the anatomical extent of gallbladder carcinoma was compared with histologic analysis, and staging accuracy was evaluated according to the TNM classification. Carcinoma considered to be at an early stage with no lymph node metastasis was correctly diagnosed in 87.5%. Differential diagnosis between early and advanced staged tumors was possible in 79.5%. Overall accuracy for depth of tumor invasion (T) was 76.9%. Limitations were due to many stones in the gallbladder and microinfiltration of carcinoma. Assessment of regional lymph node metastasis (N) was at a sensitivity of 81.8% and specificity of 92.9%, for an overall accuracy of 89.7%. We believe endoscopic ultrasonography is useful in the clinical staging of gallbladder carcinoma.

Adult↗

Analysis of microsatellite instability, TGF-beta type II receptor gene mutations and hMSH2 and hMLH1 allele losses in pancreaticobiliary maljunction-associated biliary tract tumors.

While pancreaticobiliary maljunctions (PBM) are clearly associated with biliary tract tumor development, little is known about their molecular mechanisms. This study was conducted to assess the contributions of microsatellite instability (MSI), mutations of transforming growth factor type II receptor (TGF-beta RII) and insulin-like growth factor type II receptor (IGF RII) genes and loss of heterozygosity (LOH) of hMSH2 and hMLH1 in 23 biliary tract tumors using PCR methods. MSI was detected by 13 markers in 16/23 samples (69.6%). TGF-beta RII mutations were detected in eight of these (50%), and of the IGF IIR gene in two (12.5%). LOH was detected in 4/16 (25%) at the hMSH2 locus, and 2/16 (12.5%) at the hMLH1 locus. No TGF-beta RII mutations or LOH of hMSH2 and hMLH1 were detected in MSI-negative samples. These findings suggest that MSI plays an important role in carcinogenesis of the biliary tract epithelium with PBM cases.

Adaptor Proteins, Signal Transducing↗

The prognosis of intraductal papillary mucinous tumors of the pancreas.

BACKGROUND/AIMS: Intraductal papillary mucinous tumors of the pancreas have been recognized as a distinct clinical entity. However, their biological behavior has not been clearly defined. The aim of this study was to examine the prognosis of this tumor, to clarify the biological behavior and determine the most appropriate treatment. METHODOLOGY: Correlations between prognosis of operated cases and histopathologic features were investigated. RESULTS: In 105 patients with characteristic clinical features of intraductal papillary mucinous tumors, the lesions were classified as hyperplasias in 21%, intraductal tumors in 48% and invasive carcinomas in 31%. Minimal invasion was apparent in 25%, lymph node metastasis in 21%, and fistula formation in 31% of the invasive lesions. Non-invasive and minimally invasive intraductal papillary mucinous tumors were essentially free from risk of tumor recurrence. Other invasive intraductal papillary mucinous tumors showed a significantly poor prognosis. CONCLUSIONS: Because of the variation in pathological characteristics, patient outcome and the possibility of differential diagnosis, the treatment might be recommended as follows: the case of hyperplasia can be followed-up with close surveillance. Non-invasive and minimally invasive intraductal papillary mucinous tumors should be operated with function-preserving minimal pancreatectomy. For patients with invasive intraductal papillary mucinous tumors evident with preoperative imaging modalities, radical operations with lymph node dissection might be needed.

Adenocarcinoma, Papillary↗

Evaluation of various imaging methods in the differential diagnosis of intraductal papillary-mucinous tumor (IPMT) of the pancreas.

BACKGROUND/AIMS: IPMT (intraductal papillary-mucinous tumor) of the pancreas has unique clinicopathological characteristics. The lesions which show characteristic clinical features of IPMT exhibit a wide spectrum of histological types ranging from atypical hyperplasia to invasive cancer. Therefore, surgical treatment cannot be recommended for all patients with IPMT. It is necessary to assess the malignant potential of IPMT in individual patients in order to select an appropriate approach. The aim of this study was to evaluate the effectiveness of endoscopic ultrasonography and intraductal ultrasonography as compared with ultrasonography and computed tomography for this purpose. METHODOLOGY: Ultrasonography, computed tomography, endoscopic ultrasonography and intraductal ultrasonography were performed in 49 cases of IPMT (atypical hyperplasia 7, adenoma 23, noninvasive 7 and invasive adenocarcinoma 12). On the basis of the histopathological analysis of another 28 cases of resected IPMT specimens, criteria for differential diagnosis by imaging modalities were defined as follows: Nonneoplastic lesion (atypical hyperplasia): no wall thickening or nodule; noninvasive IPMT (adenoma and intraductal carcinoma): a nodule or wall thickening is present; and invasive IPMT with pancreatic parenchymal invasion: a mass with a heterogenous pattern or interruption of the pancreatic duct wall by the mass. RESULTS: The diagnostic accuracy rate for differentiating nonneoplastic lesion noninvasive IPMT, and invasive IPMT was 33% by ultrasonography, 38% by computed tomography, 77% by endoscopic ultrasonography, and 67% by intraductal ultrasonography. Sensitivity, specificity and accuracy rates for differentiating neoplastic and nonneoplastic IPMT by ultrasonography was 33%, 100%, 42%, by computed tomography 36%, 100%, 44%, by endoscopic ultrasonography 90%, 71%, 88%, by intraductal ultrasonography 94%, 29%, 84%, respectively. Sensitivity, specificity and accuracy rates for differentiating invasive and noninvasive IPMT by ultrasonography was 25%, 100%, 80%, by computed tomography 33%, 100%, 83%, by endoscopic ultrasonography 55%, 97%, 88%, by intraductal ultrasonography 56%, 91%, 84%, respectively. Diagnostic accuracy for invasive IPMT except minimally invasive cases by endoscopic ultrasonography and intraductal ultrasonography was 80%, based on the results of the examination which demonstrated a higher grade lesion. CONCLUSIONS: With these criteria, ultrasonography and computed tomography showed high specificity, but low sensitivity for the differential diagnosis of neoplastic/nonneoplastic and invasive/noninvasive IPMT. However, endoscopic ultrasonography and intraductal ultrasonography had high sensitivity and diagnostic accuracy for the differential diagnosis of neoplastic/nonneoplastic lesions. Combination of endoscopic ultrasonography and intraductal ultrasonography showed a high accuracy rate in the diagnosis of invasive IPMT. Thus endoscopic ultrasonography and intraductal ultrasonography contributed significantly to the choice of the treatment for IPMT.

Adult↗

Prospective study of the detection of anomalous connections of pancreatobiliary ducts during routine medical examinations.

BACKGROUND/AIMS: It is important to achieve detection of of anomalous connections of the pancreatobiliary ducts (ACPBD), because this condition often leads to pancreatobiliary disease. The present prospective investigation focused on revealing the incidence of ACPBD in asymptomatic individuals undergoing medical checkups. MATERIAL AND METHODS: Extracorporeal ultrasonography (US) was performed on all asymptomatic individuals undergoing medical checkups. Identification by abdominal ultrasonography of 3 mm or more gallbladder wall thickening, or 10 mm or more dilatation of the bile duct were considered indicative of ACPBD and endoscopic ultrasonography (EUS) was carried out in selected cases. Endoscopic retrograde cholangiopancreatography (ERCP) was then performed to confirm the existence of ACPBD. RESULTS: The overall incidence of ACPBD was 0.03% (9/27,076 subjects). ACPBD was found in 23% of cases with bile duct dilatation, and in 2.9% with gallbladder wall thickening. CONCLUSION: ACPBD was not as rare a disease as expected. For early detection of ACPBD, identification by abdominal ultrasonography of gallbladder wall thickening or dilatation of the bile duct are indicative. Patients who are suspected of having this abnormality should then undergo EUS. The final diagnosis should then be made by ERCP.

Adult↗

Ras gene point mutations in gallbladder lesions associated with anomalous connection of pancreatobiliary ducts.

BACKGROUND/AIMS: The present study was undertaken to investigate possible changes in the K-ras oncogene in patients with gallbladder lesions (carcinoma, adenoma or hyperplasia) in relation to the presence or absence of an anomalous connection of pancreatobiliary ducts (ACPBD). METHODOLOGY: Gallbladder specimens were obtained from 44 patients with lesions that were either with or without ACPBD, and DNA samples were analyzed using PCR-SSCP. Point mutations in codons 12, 13 and 61 were analyzed by direct sequencing methods with oligonucleotide primers. RESULTS: The K-ras codon 12 was detected in 83.3% (5/6) of carcinomas the one adenoma tested and in 35.7% (5/14) of hyperplastic lesions with ACPBD, as opposed to only 36.4% (4/11) of carcinomas without ACPBD. The one case of gallbladder adenoma and 11 cases of normal gallbladder without ACPBD studied demonstrated no point mutations in the K-ras oncogene. CONCLUSIONS: Alteration of the K-ras oncogene appears to be involved in the early stages of gallbladder carcinogenesis when in association with ACPBD. The results further suggest that hyperplasia in cases with ACPBD may be a significant pre-cancerous lesion.

Adenocarcinoma↗