Case of intraductal papillary mucinous tumor (noninvasive adenocarcinoma) of the pancreas resected 27 years after onset.

A case of intraductal papillary mucinous tumor (IPMT) of the pancreas resected 27 yr after onset is presented. In March of 1997, a 71-yr-old man was admitted to our hospital with a complaint of severe epigastric pain. He had initially undergone endoscopic retrograde pancreatography (ERP) in April 1971 in our hospital and the patient had been followed up for pancreatografic changes for 26 yr. Dilatation of the main pancreatic duct gradually progressed during follow-up, and the filling defect owing to the tumor became demonstrable. On admission, ERP revealed diffuse dilatation of the main pancreatic duct, which was 20 mm in diameter, and the filling defect of 35 mm in diameter. We diagnosed this patient as having an IPMT of the pancreas. Considering his general condition, pancreatic segmentectomy was carried out, and the postoperative course was favorable. Histological findings were compatible with those of noninvasive papillary adenocarcinoma. This is a precious case for studying the natural history of intraductal papillary tumor of the pancreas and to evaluate the application of surgery, because the biologic behavior of this tumor is much less aggressive than that of pancreatic ductal cell carcinoma.     

Intraductal papillary-mucinous tumor of the pancreas head with complete absence of the ventral pancreatic duct of Wirsung

A case of intraductal papillary mucinous tumor of the pancreas with complete absence of the ventral pancreatic duct of Wirsung is presented. A 74-year-old Japanese man was admitted to our hospital because of elevated serum amylase concentration. Abdominal computed tomography (CT) scanning revealed diffuse dilatation of the main pancreatic duct and a diffuse and uncircumscribed area with heterogeneous density in the pancreas head. Endoscopic retrograde cholangiopancreatography revealed that the main pancreatic duct was connected with an accessory papilla and was diffusely dilated, without any irregularity of the duct wall being observed in the entire length of the duct. The common bile duct was detected only by cannulation through Vater’s papilla, and no pancreatic duct or its communicating branch was found. Some branches, directed to the dorsal portion of the pancreas head, were found arising from the accessory pancreatic duct. Intraductal ultrasound examination performed through the accessory papilla and the common bile duct revealed a small tumor with a heterogeneous echo level in the pancreas head. From these findings, intraductal papillary-mucinous tumor (IPMT) occurring in the pancreas head was diagnosed, and pylorus-preserving pancreaticoduodenectomy was performed. The resected specimen revealed IPMT in the pancreas head. A roentgenographic study of the resected specimen revealed a defect caused by the tumor located in the pancreatic duct connected with the accessory papilla and showed that there was complete absence of the pancreatic duct connected with Vater’s papilla. Surgical resection enabled us to completely analyze the duct system of pancreas divisum. Although it is not known whether there is a relationship between the pathogenesis of IPMT and embryological anomaly of the pancreatic duct system, this case may provide an insight into the pathogenesis of IPMT.     

A case report of anaplastic carcinoma of the pancreas with remarkable intraductal tumor growth into the main pancreatic duct

We herein report a case of anaplastic carcinoma of the pancreas with remarkable intraductal tumor growth into the main pancreatic duct.A 76-year-old male was referred to our hospital for treatment of a pancreatic tumor.Preoperative examinations revealed a poorly defined tumor in the main pancreatic duct in the body of the pancreas,accompanied with severe dilatation of the main pancreatic duct,which was diagnosed as an intraductal papillary-mucinous neoplasm.We performed distal pancreatectomy and splenectomy.The pathological examination revealed that the tumor consisted of a mixture of anaplastic carcinoma(giant cell type)and adenocarcinoma in the pancreas.There was a papillary projecting tumor composed of anaplastic carcinoma in the dilated main pancreatic duct.The patient is now receiving chemotherapy because liver metastasis was detected 12 mo after surgery.In this case,we could observe a remarkable intraductal tumor growth into the main pancreatic duct.We also discuss the pathogenesis and characteristics of this rare tumor with specific tumor growth.     

Intraductal papillary mucinous tumor of the pancreas: computerized tomography and magnetic resonance imaging features

The aim of this study was to analyze the computerized tomography (CT) and magnetic resonance imaging (MRI) features of intraductal papillary mucinous tumor (IPMT) of the pancreas. The cases of eight patients with pathologically proven IPMT (1 papillary hyperplasia, 7 adenocarcinoma) of the pancreas were retrospectively reviewed. There were five men and three women with ages ranging from 42 to 82 years. Imaging studies included six thin-section dynamic CT scans, seven MRI scans, one MR cholangiopancreatography scan, and two endoscopic retrograde cholangiopancreatography scans. There was only one benign IPMT, which presented as a unilocular cyst in the pancreatic body with no mural nodules and no dilatation of the main pancreatic duct (MPD). All seven patients with malignant IPMT had multilocular cysts with papillary projections in the pancreatic head and/or uncinate process accompanied by dilated MPD (5 diffuse, 2 segmental). Communication between the cystic lesions and the MPD were evident in all seven patients. One patient had small mural nodules in the branch ducts of the pancreatic body and five had a bulging papilla with a patulous orifice. A mass effect resulting in biliary obstruction was shown in one patient. One patient had a ruptured cyst with mucin leakage into the right anterior pararenal space following sono-guided aspiration. In conclusion, the main imaging feature of IPMT in our patients was a multilocular cyst with papillary projections located in the pancreatic head and uncinate process. Although CT and MRI cannot differentiate mucin content from pancreatic juice, communication between the cystic lesion and the dilated MPD and a bulging papilla with a patulous orifice are characteristics of IPMT.     

Invasive carcinoma of the pancreas derived from intraductal papillary adenocarcinoma without mucin hypersecretion but with changes in the pancreatic duct on pancreatography

We present a case of invasive carcinoma of the pancreas derived from intraductal papillary adenocarcinoma without mucin hypersecretion in a 65‐year‐old man with a 45‐year history of alcohol abuse and a 2‐year follow‐up of chronic pancreatitis. Two years previously, in May 1998, he was admitted for investigation of abdominal pain. Computed tomography (CT) showed diffuse dilation of the main pancreatic duct with atrophy of the pancreatic parenchyma. Endoscopic retrograde pancreatography (ERP) showed a diffusely dilated main pancreatic duct with irregular side branches in the head of the pancreas. Chronic alcoholic pancreatitis was diagnosed on the basis of the pancreatography findings. The patient was readmitted for investigation of progressive weight loss in August 2000. Serum CA19‐9 levels were markedly elevated (750U/ml) and CT showed enlargement of the head and body of the pancreas. ERP showed irregularity of the main pancreatic duct in the head of the pancreas, and the distal main pancreatic duct (which was dilated on initial ERP examination) was interrupted in the body of the pancreas. Suspected pancreatic carcinoma was diagnosed, and pylorus‐preserving pancreatoduodenectomy was performed. Frozen section examination of the cut end of the pancreas revealed ductal carcinoma, and total pancreatoduodenectomy with portal vein resection was performed. Histologically, the resected tumor was diagnosed as an invasive carcinoma derived from intraductal papillary adenocarcinoma without mucin hypersecretion. We recommend observing changes in the pancreatic duct on pancreatography to diagnose invasive carcinoma of the pancreas derived from intraductal papillary adenocarcinoma in a resectable state.     

Single-branch resection of the pancreas

The treatment of intraductal papillary mucinous tumors (IPMT) of the pancreas is still controversial. In this report we describe a single‐branch resection of the pancreas (SBRP), which is a new method for the removal of branch‐type IPMT of the head of the pancreas. A multilobular cystic lesion (50 × 40 mm) in the head of the pancreas was incidentally detected in an asymptomatic 40‐year‐old man who underwent a routine ultrasound examination. The tumor was carefully removed along the border of the cyst and the normal parenchyma, with complete preservation of the main pancreatic duct and the common bile duct. A pancreatic fistula developed during the postoperative period, but was well‐controlled by endoscopic naso‐pancreatic drainage. SBRP is a technically feasible procedure and this operation represents a minimally invasive alternative to any other segmental resection of the pancreas.     

Air in the main pancreatic duct associated with a pancreatic intraductal papillary mucinous neoplasm

A 62-year-old man was referred to our hospital after ultrasonographic mass screening detected a pancreatic cyst that proved to be an intraductal papillary mucinous neoplasm. Computed tomography additionally demonstrated air in the main pancreatic duct. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography delineated a filling defect in the main pancreatic duct in the body of the pancreas. The sphincter of Oddi was open. The main pancreatic duct was dilated by viscous mucin; air in the duct was attributed to consequent dysfunction of the sphincter. Laboratory findings included no significant abnormality. The patient has remained asymptomatic during follow-up. Of 25 previously reported cases with air in the duct, only 1 involved an intraductal papillary mucinous neoplasm.     

不同病理类型的胰腺导管内乳头状黏液性肿瘤的临床特征

目的 总结不同病理类型胰腺导管内黏液性乳头状瘤(IPMT)的临床表现,提高对IPMT的诊治水平.方法 回顾分析1996年3月至2008年9月间经手术切除且病理证实的49例IPMT患者的临床表现、影像学特点及病理学特征,比较分析良性、交界性、恶性IPMT的临床表现.结果 49例IPMT患者中男27例,女22例,平均年龄(58±11)岁.良性19例,交界性9例,恶性21例.3类IPMT患者在性别、发病年龄、烟酒史、胰腺炎发作史、糖尿病病史,是否存在腹痛、腰背部放射痛、腹胀、腹泻、消瘦等症状,血CEA、AST、ALT水平,肿瘤位置及肿瘤分型上的差异均无明显统计学意义.但黄疸、术前CA19-9和碱性磷酸酶水平、肿瘤直径、主胰管直径、囊性肿瘤内是否存在隔膜、附壁结节的大小等方面的差异有统计学意义.恶性IPMT术后5年有1例病死,1例复发;交界性和良性IPMT有1例复发,1例因其他疾病病死.结论 不同病理类型的IPMT 临床特征存在一些差异,需综合判断进行鉴别.     

Intraductal papillary-mucinous tumors of the pancreas: differential diagnosis between benign and malignant tumors by endoscopic ultrasonography

OBJECTIVES: Recently, intraductal papillary-mucinous tumor (IPMT) of the pancreas has increasingly been recognized. However, differential diagnosis between benign and malignant IPMT is often difficult using conventional imaging modalities. The purpose of this study was to retrospectively investigate the value of endoscopic ultrasonography (EUS) for differentiating malignant from benign IPMT. METHODS: A total of 51 patients with IPMT were preoperatively examined by EUS. The endosonograhic findings were compared with histopathological findings of the resected specimens. RESULTS: In main duct type IPMT, the diameter of the main pancreatic duct (MPD) was > or =10 mm in seven of the eight malignant tumors, compared with two of the seven benign tumors (p < 0.05). In branch duct type IPMT, three of the four large tumors (>40 mm) with irregular thick septa were malignant lesions. In both main duct type IPMT and branch duct IPMT, eight patients had large mural nodules (>10 mm); seven of the eight tumors were malignant and one of the eight tumors was benign. When the tumor was diagnosed as malignant according to above three findings, EUS was able to differentiate between malignant and benign IPMT with an accuracy of 86%. CONCLUSIONS: Main duct type tumors with > or =10 mm dilated MPD, branch duct type tumors (>40 mm) with irregular septa, and large mural nodules (>10 mm) strongly suggest malignancy on EUS. EUS would be a useful modality for differentiating between benign and malignant IPMT.     

Focal ductal branch dilatation on magnetic resonance cholangiopancreatography: a hint for early diagnosis of pancreatic carcinoma

A 63-year-old man with a combination of early pancreatic carcinoma and an intraductal papillary adenoma was reported. A pancreatic cyst was detected by chance at the head of the pancreas by computed tomography for a follow-up study of early rectal carcinoma previously operated. Detailed studies by endoscopic retrograde pancreatography (ERP) showed irregular narrowing of the main pancreatic duct at the pancreatic body and magnetic resonance cholangiopancreatography (MRCP) revealed dilatation of ductal branches draining there. Brushing cytology of the pancreatic duct demonstrated cancer cells and total pancreatectomy was performed. Stepwise histo-pathological examinations of the specimen showed two foci of invasive carcinoma in the neck and body and multiple foci of severe dysplasia, some of which contained carcinoma in situ, in the body of the pancreas. The cystic tumor in the head of the pancreas was an intraductal papillary adenoma. In this case, the scrutiny of a pancreatic cyst including MRCP and ERP led to an early diagnosis of pancreatic cancer. Dilatation of ductal branches depicted by MRCP might be a new hint for early diagnosis of pancreatic carcinoma.     

Focal Ductal Branch Dilatation on Magnetic Resonance Cholangiopancreatography: A Hint for Early Diagnosis of Pancreatic Carcinoma

A 63-year-old man with a combination of early pancreatic carcinoma and an intraductal papillary adenoma was reported. A pancreatic cyst was detected by chance at the head of the pancreas by computed tomography for a follow-up study of early rectal carcinoma previously operated. Detailed studies by endoscopic retrograde pancreatography (ERP) showed irregular narrowing of the main pancreatic duct at the pancreatic body and magnetic resonance cholangiopancreatography (MRCP) revealed dilatation of ductal branches draining there. Brushing cytology of the pancreatic duct demonstrated cancer cells and total pancreatectomy was performed. Stepwise histo-pathological examinations of the specimen showed two foci of invasive carcinoma in the neck and body and multiple foci of severe dysplasia, some of which contained carcinoma in situ, in the body of the pancreas. The cystic tumor in the head of the pancreas was an intraductal papillary adenoma. In this case, the scrutiny of a pancreatic cyst including MRCP and ERP led to an early diagnosis of pancreatic cancer. Dilatation of ductal branches depicted by MRCP might be a new hint for early diagnosis of pancreatic carcinoma.     

Intraductal papillary and mucinous pancreatic tumour: a new extracolonic tumour in familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is characterised by the development of numerous colorectal adenomatous polyps. Other extracolonic benign or malignant lesions have been reported previously in association with FAP but precancerous lesions in the pancreas have never been described. We report the first case of intraductal papillary and mucinous pancreatic tumour (IPMT) in a patient with FAP. A 48 year old man with a well documented past history of FAP was admitted for epigastric pain, weight loss, and new onset diabetes mellitus. Spiral computed tomography scan revealed a large tumour in the pancreatic head with upstream main pancreatic duct dilatation. Endoscopic ultrasonography confirmed these data. Mucous secretion was seen at duodenoscopy and a lesion in the main pancreatic duct was confirmed by retrograde pancreatography. The patient underwent a pancreaticoduodenectomy for suspected IPMT. Histological examination of the resected specimen confirmed an IPMT with in situ carcinoma. Twelve months after resection, the patient remained free of tumour relapse. Genetic analysis showed loss of the wild allele of the adenomatous polyposis coli gene in IPMT, causing inactivation of both alleles and demonstrating that IPMT was not incidental in this patient. IPMT should be included in the extracolonic localisation of FAP.     

Intraductal papillary-mucinous adenoma developed in the ventral pancreas in a patient with pancreas divisum

A 34-year-old man was admitted to our hospital with the chief complaints of back pain and epigastralgia. The physical examinations on admission disclosed no abdominal tumor. The serum concentration of total bilirubin was 1.4?mg/dl. The serum elastase-1 level was elevated to 526?ng/dl. Computed tomography showed a cystic lesion, 1?cm in diameter, in the head of the pancreas, without dilatation of the main pancreatic duct. Endoscopic retrograde cholangiopancreatography via the papilla of Vater and the accessory papilla revealed an enlarged ventral pancreatic duct and pancreas divisum. The preoperative diagnosis was mucin-producing pancreatic tumor in the ventral pancreas of a patient with pancreas divisum. A pylorus-preserving pancreatoduodenectomy was performed. The gross findings of the cut surface of the resected specimen disclosed mural nodules in the dilated duct of the ventral pancreas. A histological examination of the mural nodules in the ventral pancreas revealed mucin and intraductal papillary adenoma. Benign tumors associated with pancreas divisum are rare; to the best of our knowledge, only three cases have been reported. Although in these three patients the tumor developed in the dorsal pancreas, the tumor developed in the ventral pancreas in our patient.     

A resected case of multiple intraductal papillary mucinous tumors of the pancreas with US-guided ductal branch-oriented partial pancreatectomy.

A 69-year-old man with epigastralgia was admitted on August 26, 2002 and diagnosed with multiple intraductal papillary mucinous tumors by various imagings. The cystic tumor of pancreas head had a diameter of 2 cm, and the mural nodule of the cystic tumor measured only 3 mm. In the pancreas body the cystic tumor was measured at 1.5 cm with the mural nodule of the cystic tumor measuring 3 mm. It was believed that the tumors were benign. However, a mural nodule of the cystic lesion was recognized, thus, the possibility of malignancy could not be completely ruled out. The reduction operation for preservation of pancreatic parenchyma should be selected for these circumstances. Ductal branch-oriented partial pancreatectomy was performed on September 6, 2002 with intraoperative ultrasonography and a Cavitron Ultrasonic Aspirator, preserving the main pancreatic duct and normal pancreatic parenchyma. The operation was successful, and the histopathological diagnosis of the tumors was intraductal papillary adenoma of the pancreas.     

Pancreatic endocrine tumors with intraductal growth into the main pancreatic duct and tumor thrombus within the portal vein: a case report and review of the literature

Pancreatic endocrine tumors are rare tumors classified into "functioning" and "nonfunctioning" tumors. A 68-year-old man was admitted to our hospital with the chief compliant of abdominal pain. Various imaging studies demonstrated a mass in the head of the pancreas with intraductal growth into the main pancreatic duct and an intraportal mass. The patient underwent a curative surgical operation. Histopathological examination revealed that it was nonfunctioning endocrine carcinoma of the pancreas. This is the first reported case of a pancreatic endocrine tumor with intraductal growth into the main pancreatic duct and tumor thrombus within the portal vein.     

Clinicopathologic study of intraductal papillary-mucinous tumors and mucinous cystic tumors of the pancreas

BACKGROUND/AIMS: We analyzed clinicopathologic and imaging findings of intraductal papillary-mucinous tumors (IPMTs) and mucinous cystic tumors (MCTs) of the pancreas to evaluate the difference between IPMTs and MCTs, and to identify the signs indicative of malignancy in IPMTs. METHODOLOGY: Clinicopathological features of 20 patients with IPMT and six patients with MCT of the pancreas were studied. RESULTS: The patients with IPMT comprised 16 males and four females with a mean age of 62.9 years. Eighty percent of IPMTs were located in the pancreatic head, and the mean tumor size was 38.6mm. Recurrence was observed in one patient, who died of IPM adenocarcinoma. In contrast, all patients with MCT were females, with a mean age of 53.0 years. None of the MCTs arose in the pancreatic head, and the mean tumor size was 42.7mm. One patient died of MC adenocarcinoma, but all of the others survived without recurrence. The difference in gender, location of the tumor, and connection to the pancreatic duct reached statistical significance between IPMTs and MCTs. A significant connection to the pancreatic duct and high level of serum carbohydrate antigen 19-9 (CA19-9) was observed in the adenocarcinoma and moderate dysplasia groups of IPMT. CONCLUSIONS: The main duct type and an elevation of serum CA19-9 level suggested malignancy in IPMTs.     

Intraductal papillary and mucinous tumor of the pancreas: a case report of successful surgical treatment with decompression

Intraductal papillary mucinous tumor of the pancreas is commonly regarded as histopathologically low-grade malignancy. As yet, no fixed strategy of treatment for the advanced aged patient with intraductal papillary mucinous tumor exists. An 80-year-old woman was admitted to our hospital in July 1996 because of back pain due to pancreatitis. Examinations showed a widely opened orifice of the ampulla of Vater, the mural nodule in the cystic lesion of the pancreas uncus, and a mucinous plug in the diffusely dilated main pancreatic duct, so the patient was diagnosed as having intraductal papillary mucinous tumor in the pancratic head. However, in view of the patient's advanced age and the fact that intraductal papillary mucinous tumor is commonly regarded as a slow growing and histopathologically low-grade malignancy, we refrained from radical operation and selected the best supportive care. Four years subsequent to this, her symptoms became uncontrollable and she returned to our hospital. In consideration of her age, side-to-side pancreaticojejunostomy as minimally invasive surgery was employed. The postoperative course was uneventful. The symptoms, biochemical profiles and images improved and she was discharged from the hospital 28 days after the operation. No event has been observed in the patient for one year after operation. Surgical decompression is considered to be effective minimally invasive surgery for intraductal papillary mucinous tumor.     

Differential diagnosis of intraductal papillary‐mucinous tumor of the pancreas by endoscopic ultrasonography and intraductal ultrasonography

Background: Intraductal papillary‐mucinous tumor (IPMT) of the pancreas has a broad spectrum of histology ranging from hyperplasia to adenocarcinoma. Therefore, it is important to differentiate between the malignant and benign lesions to determine the therapeutic strategy for IPMT. Patients and Methods: Thirty‐nine patients with IPMT (27 men and 12 women, mean age: 63.3 years) underwent surgery between January 1985 and March 2002. The size of the cystic lesion, the maximum diameter of the main pancreatic duct (MPD), and the height of the papillary tumor inside the cyst were investigated by endoscopic ultrasonography (EUS) and/or intraductal ultrasonography (IDUS) before operation. These preoperative clinical findings were compared with the pathological findings of the resected specimen. Results: The size of the cystic lesion, the diameter of MPD, and the height of the papillary tumor in cases with malignant IPMT (invasive and non‐invasive carcinoma) were larger than those in cases with benign IPMT (adenoma and hyperplasia). Analysis of the images of the lesions revealed that the following three factors are important for diagnosing IPMT: (i) the size of the cystic lesion is ≥ 30 mm; (ii) the diameter of MPD is ≥ 8 mm; (iii) the height of the papillary tumor inside the cyst is ≥ 3 mm. It was not significant to differentiate between benign and malignant IPMT based on factor (i), but statistically significant (P < 0.001) based on factors (ii) and (iii). Conclusions: EUS and IDUS are useful in the differential diagnosis of IPMT, especially in the differentiation between malignant and benign IPMT.     

IDUS IN THE DIAGNOSIS OF IPMT

Intraductal papillary mucinous tumor of the pancreas (IPMT) is considered as having low‐grade malignant potential, and malignancy is not infrequent. Therefore, accurate diagnosis is indispensable for appropriate patient care. IPMT is classified mainly into two categories based on the distribution of tumor, the main duct type and the branch duct type. In the diagnosis of IPMT, there are four important points: differentiation of IPMT from other pancreatic pathologies; differentiation of malignancy from benign lesions; evaluation of tumor extent along the MPD; and investigation of duct cell carcinoma coexistent with or derived from IPMT. IPMT should be distinguished from chronic pancreatitis, ductal adenocarcinoma, or cystic neoplasms. IPMT often requires pancreaticoduodenectomy for cure, but such invasive surgery should be avoided in patients with benign hyperplasia. Mural nodules in the MPD can be clearly visualized by intraductal ultrasonography (IDUS). Measurement of the height of the tumor mass by IDUS is useful in distinguishing benign from malignant IPMT. Intraductal spread of IPMT along the MPD is demonstrated by IDUS as irregular thickening of the MPD wall. To achieve a tumor‐free margin in surgery, evaluation by IDUS of the extent of the tumor along the MPD is important. The expected accuracy of IDUS in the diagnosis of invasive IPMT is reportedly over 90%.     

Long-term follow-up of intraductal papillary adenoma of the pancreas

Intraductal papillary mucinous tumors of the main pancreatic duct are often considered to be premalignant or malignant, and therefore surgical resection is recommended. We report two autopsy cases of intraductal papillary mucinous tumor of the pancreas following long-term observation. The first patient was an 84-year-old man with early gastric cancer treated by endoscopic mucosectomy. The second patient was a 77-year-old man with hepatocellular carcinoma treated by percutaneous pure ethanol injection and transarterial embolization. In both patients, endoscopic retrograde pancreatography showed a diffusely dilated main pancreatic duct, with intraductal filling defects expressing mucus, as well as dilated side branches. Obvious intramural nodules were not detected. Due to their advanced age and personal requests, both patients were managed conservatively and followed nonoperatively. In the first patient, serial pancreatograms showed progression of the pancreatic duct dilatation. Both patients died of gastric cancer, the first patient 7¹/₂ years and the second, 10 years after first presentation, respectively. Autopsies revealed extensive intraductal papillary adenoma throughout the dilated mucus-filled main pancreatic duct. However, there was no evidence of progression to adenocarcinoma. Based on these observations, we suggest that, in patients with intraductal papillary mucinous tumor of the pancreas without obvious intramural nodules, even if the tumor is in the main pancreatic duct, pancreatectomy may not be mandatory, particularly in the elderly. Received: March 21, 2001 / Accepted: July 6, 2001 Reprint requests to: T. Kamisawa