Biomedical subjects

Y Esaki

Publications and source records attributed to Y Esaki.

At least 37 records · Page 2Linked to original sources

PubMed1999

Persistent infection of hepatitis C virus in the elderly: a clinical and quantitative pathological study of autopsy cases.

AIMS/BACKGROUND: The entire spectrum of persistent infection by hepatitis C virus (HCV) is still unknown. METHODS: A total of 37 autopsy cases, positive with second generation anti-HCV ELISA, were analyzed. The cases comprised 15 males and 22 females, the average ages being 76.5 in males and 81.1 in females. Twenty-one cases were found to be asymptomatic, while 16 were symptomatic. RESULTS: Based on two pathological parameters of hepatic fibrosis and inflammation, the cases were divided into five groups; group A (non-inflammatory group without significant fibrosis; 11 cases), group B (inflammatory group without significant fibrosis; 9 cases), group C (non-inflammatory group with significant fibrosis; 1 case), group D (inflammatory group with significant fibrosis; 11 cases) and group E (undetermined inflammatory index; 5 cases). All cases in group A and seven cases in group B were asymptomatic. Group A included 6 cases with normal liver. All cases in groups C and D were symptomatic. All examined cases of the inflammatory groups were positive for serum HCV-RNA. CONCLUSION: Anti-HCV-positive elderly autopsy patients include many asymptomatic cases. The two pathological parameters of hepatic fibrosis and inflammation can be used to divide the cases into five groups with each group being well correlated with clinical and virological features.

Adult↗

PubMed1999

Implications of marked fatty infiltration around and in the atrophic atrioventricular node in elderly patients with permanent pacemaker implantation for symptomatic sick sinus syndrome.

The present study undertook an extensive analysis of the histopathological findings of the atrioventricular conduction system in 14 elderly patients treated with permanent pacemakers for sick sinus syndrome (SSS). Special attention was given to the lowest Wenckebach block points of atrioventricular conduction during rapid atrial pacing, and ventricular rate or duration of ventricular pause during chronic atrial fibrillation. An electrophysiological study (EPS) was conducted under sinus rhythm in 13 patients and under junctional escape rhythm in 1 patient. Three of the 14 cases showed a lower Wenckebach block point of 130 beats/min or less. Two of these 3 cases showed excessive fatty infiltration around the atrionodal junction area and into the atrophic atrioventricular node (AVN) itself. Of the 6 patients who had chronic atrial fibrillation after pacemaker implantation, 2 cases showed a slow ventricular response of less than 60 beats/min and/or a long ventricular pause of 3.3 s. One of the 2 cases showed a lower Wenckebach block point of 130 beats/min at the time of EPS. The other, who later progressed to idiopathic atriomegaly, also showed marked fatty infiltration around the AVN. This fatty lesion was closely associated with diffuse disruption of the muscular fibers connecting the atrophic AVN with the atrium. In addition, most of the remaining cases also had an atrophic AVN. In conclusion, a sparse or absent atrionodal connection and an atrophic AVN due to excessive fatty infiltration in the atrionodal transitional area should be investigated in atrioventricular conduction disturbances in the elderly with SSS.

Aged↗

PubMed1999

[Pathologic evaluation of the main cause of death in Japanese centenarians].

A total of 42 Japanese centenarians (9 males & 33 females) autopsied in Tokyo Metropolitan Geriatric Hospital during 22 years (1975-1996) were clinico-pathologically examined to determine details of the main cause of death. The main cause of death of the 42 cases were sepsis (16 cases), pneumonia (14 cases), suffocation (4 cases), heart failure (4 cases), cerebrovascular disorder (2 cases) and malnutrition (2 cases). Most pneumonias were caused aspiration of foreign bodies, and the origins of sepsis were pyelonephritis (7 cases), biliary tract infection (3 cases), necrotic lesions of the intestine due to ileus, ischemia and pseudomembranous colitis (3 cases) and indwelling vein catheter (3 cases). Malignant neoplasms were observed in 16 cases (38%), and 5 of them had 2 or 3 lesions. Thus, the total number of lesions of malignant neoplasms were 22, as follows; colonic cancer (36%), urinary bladder cancer (14%), lung adenocarcinoma (9%), gastric cancer (9%), malignant lymphoma (9%) and others. However, none of these malignant neoplasms were directly related with the cause of death. All 42 centenarians died not of simple "senile decay", but due to diseases.

Aged↗

PubMed1998

Histologic and biologic patterns of microscopic pancreatic ductal adenocarcinomas detected incidentally at autopsy.

BACKGROUND: The major clinical problems with pancreatic carcinoma are its silent course and late, fatal clinical manifestation. The results of treatments of small pancreatic carcinomas (<2 cm in greatest dimension) have led to the assumption that the detection of these cancers at earlier stages would lead to better survival and possible cure. Currently, there is no information about the histologic and biologic patterns of early stage pancreatic carcinoma, and the available data on incidentally detected tumors are fragmentary. The authors observed two incidental microscopic pancreatic ductal adenocarcinomas in female patients who died of advanced gastric carcinoma (Case 1) and renal carcinoma (Case 2). METHODS: The pancreatic lesions were examined histologically in serial sections and immunocytochemically for islet cells. Microdissection was performed so that the lesions could be examined for c-Ki-ras mutation. RESULTS: In Case 1, the pancreatic lesion was composed of cystic and solid components. The cystic component consisted of four small cysts compatible with a mucinous cystic tumor and showed no invasion. The solid component was a well-differentiated adenocarcinoma that occupied a 4 x 2 mm area. In Case 2, the pancreatic lesion contained two small, separate cysts, one of which was surrounded by two apparently separate, invasive adenocarcinomas 2.6 x 0.7 mm and 1.2 x 0.5 mm in greatest dimension. There was invasion of pancreatic islets and perineural spaces in both cases; and in Case 2, there was invasion of peripancreatic fatty tissue. In both cases, the epithelia of the cystic components and tumors showed mutation of the c-Ki-ras oncogene at codon 12, with GGT-to-GAT transition. CONCLUSIONS. Pancreatic carcinoma seems to occur under occult circumstances and maintain a silent course. Even in its early developmental stage, the cancer is invasive, primarily affects islets and nerves, and exhibits mutation of the c-Ki-ras oncogene. These findings call for urgency in the development of preventive modalities.

Aged↗

PubMed1998

Induction of autoimmune arthritis in HLA-DR4 (DRB1*0401) transgenic mice by immunization with human and bovine type II collagen.

Although associations between the expression of particular HLA genes and the susceptibility to specific autoimmune diseases has been known for some time, the role that these HLA molecules play in the autoimmune response is unclear. Through the establishment of a chimeric HLA-DR/I-E transgene, we have examined the function of the rheumatoid arthritis (RA) susceptibility allele HLA-DR4 (DRB1*0401) in presenting antigenic peptides derived from the model Ag, type II collagen (CII), and in mediating an autoimmune response. As a transgene, the chimeric DR4 molecule conferred susceptibility to an autoimmune arthritis induced by immunization with human CII or bovine CII. These mice developed an inflammatory, autoimmune arthritis that was similar both histologically and in severity to that previously described for the collagen-induced arthritis model. The DR4-mediated autoimmune arthritis was accompanied by T cell and B cell responses to both the immunogen and the autoantigen, murine CII. The DR4-restricted T cell response to human CII was focused on an immunodominant determinant within CII263-270 and a minor determinant within CII286-300, the same CII determinants recently identified for yet another RA susceptibility allele, HLA-DR1 (DRB1*0101). Thus these data demonstrate that, like HLA-DR1, HLA-DR4 is capable of binding peptides derived from human CII and therefore probably plays a role in the autoimmune response to human CII observed in RA patients.

Amino Acid Sequence↗

PubMed1998

Pancreatic mucin-producing adenocarcinoma associated with a pancreatic stone: report of a case.

We present an autopsy case of an 83-year-old Japanese man with a mucin-producing adenocarcinoma accompanied by pancreatolithiasis in the head of the pancreas. He suffered from obstructive jaundice and died of disseminated intravascular coagulation. He did not normally drink alcohol and had no history of chronic pancreatitis. The autopsy findings revealed a mucinous cystic tumor, composed of multiple dilatated branches, in the head of the pancreas. Histological examinations showed papillary adenocarcinoma, which scirrhously infiltrated the distal common bile duct with perineural invasion and lymph node involvement. He was thus diagnosed to have mucin-producing branch-type cancer in the head of the pancreas. The main pancreatic duct was dilated, and the residual pancreatic tissue showed moderate fibrosis and parenchymal atrophy. A stone was observed in a dilated branch of the primary lesion. To the best of our knowledge, there have only been five previously reported cases of mucin-producing tumor associated with pancreatolithiasis. Intraductal calcification is a major characteristic of chronic pancreatitis, but it is clinically important not to misdiagnose cancers associated with pancreatolithiasis such as chronic pancreatitis.

Adenocarcinoma, Mucinous↗

PubMed1998

Extreme right lobar atrophy of the liver: a rare complication of autoimmune hepatitis.

Lobar atrophy is a rare morphologic change of the liver. We describe a 73-year-old woman with mild liver dysfunction and history of Sjögren's syndrome who had right hepatic lobar atrophy. Serum biochemistry levels were as follows: albumin, 4.5 g/dl; total bilirubin, 1.0 mg/dl; alanine aminotransferase, 25 international units/l; aspartate aminotransferase, 27 international units/l; alkaline phosphatase, 333 international units/l; and gamma-glutamyl transpeptidase, 332 international units/l. Serological data were as follows: rheumatoid factor, 27.9; anti-nuclear antibody, 1:640; and antismooth muscle antibody, 1:80. Viral markers for hepatitis B were all negative. Anti-hepatitis C virus (anti-c-100) was negative. Portal hypertension developed thereafter, and the patient died of hepatic failure at age 76. Postmortem examination revealed autoimmune hepatitis with moderate fibrosis, portal vein thrombus, and complete obstruction of the right hepatic duct due to hepatolithiasis. Terminal hepatic failure resulted from combination of decreased hepatic volume due to the right lobar atrophy, exacerbation of autoimmune hepatitis in the remnant left hepatic lobe, decreased portal venous blood flow due to thrombosis, portal hypertension, and cholangitis with hepatolithiasis. This is the first reported case of hepatic lobar atrophy due to autoimmune hepatitis. From a clinical standpoint, patients with hepatic lobar atrophy, even if asymptomatic, should be followed up with careful attention to progression of liver diseases, portal hypertension, and biliary complications.

Aged↗

PubMed1997

Restricted TCR V alpha repertoire in the T cell response to a tolerogenic determinant of type II collagen.

Tolerization of B10.RIII mice (H-2r) with i.v.-injected type II collagen (CII) renders the animals resistant to induction of collagen-induced arthritis (CIA). The B10.RIII mouse is of particular interest, in that the T cell determinants that induce tolerance are different from those that induce arthritis. To characterize T cells that react with the tolerogenic determinant and play a role in regulation of arthritis, we have developed a panel of T cell hybridomas reactive with the tolerogenic T cell epitope, CII 607-621. None of the hybrids cross-reacted with either the arthritogenic CII 445-453 or murine CII. As determined by PCR and immunofluorescence, the T cell response to the tolerogenic determinant was oligoclonal, with evident preferential usage of V alpha. Through the analysis of a large panel of T cell hybridomas, preferential usage of V alpha2, J alpha44, J beta2.7, and D beta2.1 was observed. Characterization of T cells reactive with the immunodominant determinant, CII 607-621, responsible for the induction of tolerance should prove important in developing novel therapeutic approaches for the treatment of autoimmune diseases.

Amino Acid Sequence↗

PubMed1997

Heterogeneity of DNA ploidy pattern in carcinoma of the gallbladder: primary and metastatic sites.

There are few detailed reports on the heterogeneity of the nuclear DNA ploidy pattern in carcinoma of the gallbladder. We studied twelve autopsied cases who died of extended gallbladder carcinoma. Multiple samples were taken from the primary site (Pri), from direct invasion of the liver (Hinf), from hematogenous metastasis to the liver (H), from lymphatic metastasis (LN) and from peritoneal dissemination (P). The DNA ploidy pattern was investigated by image cytometry. Heterogeneity of the DNA ploidy pattern in Pri, Hinf, H, LN and P was found in 7/11, 2/10, 5/10, 2/6 and 3/6 cases, respectively. Aneuploidy was more frequently found in Hinf than at the Pri. The DNA index of Hinf was significantly higher than that of Pri. Several stemlines, with different quantities of DNA, were found in Pri. Most of these stemlines were also observed in other sites. These facts may suggest that polyclonal cancer cells rather than one cancer cell or monoclonal cancer cells of a Pri metastasize or infiltrate, and that various polyclonal cancer cells proliferate to different degrees under different circumstances.

Aged↗

PubMed1997

Embolic brain infarction in nonrheumatic atrial fibrillation: a clinicopathologic study in the elderly.

Although CT studies have addressed symptomatic and asymptomatic cerebral infarctions in nonrheumatic atrial fibrillation (NRAF), pathologic verification of the results is lacking. The purpose of this study was to assess the frequency, location, and extent of symptomatic and asymptomatic brain infarction in autopsy specimens from elderly patients with NRAF. We examined autopsy specimens from 136 consecutive NRAF patients 70 years of age or older who received no anticoagulant therapy during their lifetime and compared them with 231 age-matched control subjects with similar health histories except for the absence of NRAF. Symptomatic cerebral infarctions were present in 82 (60.3%) NRAF patients and in 55 (23.8%) control subjects (p < 0.0001). Of symptomatic cerebral infarctions, cardioembolic infarction was present in 53 (64.6%) NRAF patients and in two (3.6%) of the control subjects (p < 0.0001), atherothrombotic infarction in 13 (15.9%) NRAF patients versus 36 (65.5%) control subjects (p < 0.0001), and lacunar infarction in four (4.9%) NRAF patients versus 12 (21.8%) control subjects (p < 0.01). Stroke-related death occurred in 34 (25.0%) NRAF patients and in 18 (7.8%) control subjects (p < 0.0002). Symptomatic cerebral infarction was generally accompanied by asymptomatic infarctions in both NRAF patients and control subjects. Asymptomatic cortical infarctions were more common in NRAF patients, but asymptomatic infarctions in the white matter or deep structures were more common in control subjects. In this autopsy series of individuals over 70 years of age, symptomatic brain infarction was 2.5 times more common in NRAF patients than in NRAF-free control subjects; two-thirds of the infarctions in the NRAF cases were judged to be cardioembolic in origin. Most asymptomatic cerebral infarctions in the NRAF patients were located in the cortices.

Aged↗

PubMed1997

Paroxysmal atrial fibrillation: high frequency of embolic brain infarction in elderly autopsy patients.

We examined brains clinicopathologically from 54 consecutive paroxysmal atrial fibrillation (PAF) patients aged 70 years or older and compared them with those of 59 age-matched controls. Symptomatic cerebral infarctions were present in 29 PAF patients (53.7%) and in 13 controls (22.0%) (p < 0.001). Symptomatic brain infarction was 2.4 times more common in PAF cases than in PAF-free controls; approximately 60% of the infarctions in the PAF cases were judged to be cardioembolic in origin. PAF in the elderly can be an important cause for cardiogenic cerebral embolism.

Aged↗

PubMed1997

[Autopsy findings of gastric mucosa from elderly people without gastric disease].

Results of pathological studies of surgical specimens have led to widespread acceptance of the belief that with aging the gastric mucosa gradually becomes atrophic and the incidence of intestinal metaplasia increases. To distinguish natural age-related changes in the incidence of fundic gland atrophy and intestinal metaplasia from changes related to disease, we studied stomachs removed at autopsy from 187 people who had had no gastric diseases and were over 60 years old at the time of death (27 were over 100 years old). The autopsies were performed at Tokyo metropolitan geriatric hospital. None of the stomachs had circumscribed gastric lesions, and those found to have cancer or ulcer were excluded. Age at the time of death was not associated with the incidence of fundic gland atrophy or of intestinal metaplasia. Thus, the incidences of fundic gland atrophy and of intestinal metaplasia in elderly people were much lower than those found in studies of surgical specimens. In addition, the incidences of fundic gland atrophy and of intestinal metaplasia did not differ significantly between the sexes, regardless of age.

Aged↗

PubMed1997

[Gastric cancer in the elderly--relationship between macroscopic appearance and histological type in autopsy specimens].

OBJECTIVE: We sought to clarify the characteristics of gastric cancer in the elderly. METHODS: We examined 349 specimens of gastric cancers. All specimens were obtained at autopsy from patients who were over 65 years old. We analyzed the relations among five factors: age of the patient, histological type, macroscopic appearance, grade of invasion and location. RESULTS: Older patients were more likely to have papillary adenocarcinoma, tubular adenocarcinoma, and Borrmann-2 and 3 lesions. Papillary and tubular adenocarcinoma together accounted for 14 of 84 Borrmann-4 lesions (16.3%). Borrmann-1 signet-ring-cell carcinomas were observed in two cases. Tubular adenocarcinomas made up 31 in 38 depressed-type early carcinomas (81.6%). Over half of the papillary and tubular adenocarcinomas were confined to the mucosal or submucosal layers, but over 60% of the poorly differentiated adenocarcinomas or signet-ring-cell carcinomas had invaded the extraserosal layer. Papillary and tubular adenocarcinomas were commonly found in the lower part of the stomach, but poorly differentiated adenocarcinomas and signet-ring-cell carcinomas were found in all parts of the stomach. CONCLUSIONS: Unlike specimens obtained during surgery, many of those obtained at autopsy were from older patients, and the gastric cancers were advanced. Compared to many reports about specimens obtained during surgery, tubular or papillary adenocarcinomas are not a few histological type in Borrmann-4 lesions in this study. Surgical specimens of depressed-type early cancer in younger patients are most commonly found to be signet-ring-cell carcinoma, but tubular adenocarcinoma was common in this study. We found many differences between specimens obtained at autopsy and during surgery. These findings indicate that autopsy studies can reveal some otherwise-obscure characteristics of gastric cancer in the elderly.

Adenocarcinoma↗

PubMed1997

Grossly punched-out lesions in the aorto-iliac region can be histologically classified as false, pseudo-false, or disguised aneurysm.

Aneurysms are morphologically classified as true or false based on the nature of their walls. True aneurysms are composed of all or parts of layers of the vessel. False aneurysms are the result of rupture and their walls have only fibrous tissues. The orifice of false aneurysms is narrow relative to the aneurysmal diameter and thus they are grossly or angiographically referred to as punched-out lesions. Hence false aneurysms present with punched-out lesions, but in reverse, are all of punched-out lesions false aneurysms? We experienced some cases of punched-out lesions which histologically contained traces of elastin, and the purpose of this report was to histologically investigate grossly punched-out lesions. We examined 671 elderly autopsy cases, and a total of 21 grossly punched-out lesions in the aorto-iliac region were selected. They were histologically classified as false, "pseudo-false", or "disguised" aneurysm. False aneurysms were found in 3 patients (0.45%), and were histologically mycotic. A total of 5 "pseudo-false" aneurysms were found in 3 patients (0.45%). They histologically contained traces of elastin, and thus they were categorised in true aneurysms. A total of 13 "disguised" aneurysms were found in 6 patients (0.89%). They were true fusiform aneurysms with an eccentric thrombus, on which a fibrin-cap formed a narrow orifice. Partial sections are insufficient for diagnosis; cross-sections are necessary. To the best of our knowledge, there have been no reports of "pseudo-false" or "disguised" aneurysms in the aorto-iliac region.

Aged↗

PubMed1996

Mucin-producing adenoma associated with pancreas divisum and hepatic hilar carcinoma: an autopsy case.

We present the autopsy case of an 82-year-old Japanese woman with a mucin-producing adenoma accompanied by pancreas divisum and a hepatic hilar carcinoma. She had suffered from a cholangiocellular carcinoma at the hepatic hilus for 2 months, which was treated with radiation and chemotherapy. She did not complain of any abdominal pain. Obstructive jaundice deteriorated despite percutaneous transhepatic bile duct drainage, and she died of hepatic insufficiency. At autopsy, a hepatic tumor was confirmed to have caused severe obstructive jaundice. Histological examinations showed moderately to poorly differentiated cholangiocellular adenocarcinoma with squamous metaplasia, probably due to radiation. A yellowish mucinous tumor was found in the head of the pancreas near the minor papilla. It consisted of multiple rice-sized cystic lesions with thin septa. Although it had no capsule, its margin was clear. Neither a wide opening of the major or minor papilla nor mucous drainage was observed. Gross examinations revealed unfused pancreatic ducts. The slightly dilatated dorsal duct and a branch of the mildly dilatated ventral duct showed tumor involvement. Histological examinations showed mild atypia of the epithelia, and this pancreatic tumor was diagnosed as branch duct-type mucin-producing adenoma with postradiation dysplasia. The combination of a mucin-producing tumor and pancreas divisum is rare, and this is only the third reported case.

Adenoma↗

PubMed1996

[Clinical and pathological study of gastric cancer treated without surgery in elderly patients].

OBJECTIVE: To clarify the clinical and pathological characteristics of gastric cancer in the elderly. METHOD: Clinical and pathological characteristics of patients who died during 1986-94 with gastric cancer which did not undergo surgery were studied retrospectively. The patients were divided into three groups according to age: A (65-74 years, n = 38), B (75-84 years, n = 77), and C (85 years and over, n = 43). RESULTS: Borrman type-1 was more frequent in group C and Borrman type-4 was frequent in group B. "Early cancer", protruded type (type I or type IIa) was more frequent in group C. In cases of advanced cancer some patients did not undergo surgery because the cancer was to advanced, and others had concomitant diseases that made surgery risky. In all groups, a few patients refused surgery. In cases of "early cancer", the most reason for not undergoing surgery was a concomitant disease in all groups. Other reasons were general weakness and dementia in group C, second malignancy and dementia in group B, and second malignancy in group A. After advanced cancer was diagnosed, 9.6% survived for 1 year, and 1.7% for 2 years. After early cancer was diagnosed, 50.7% survived for 1 year, 15.2% for 3 years and 7.8% for 4 years. The survival rates did not differ by age. In all age groups, gastric cancer was frequently the main cause of death in patients with advanced cancer, but many patients with "early cancer" died of other causes.

Age Factors↗

PubMed1996

[Clinicopathologic study of mitral regurgitation due to abnormal chordae tendineae].

Severe mitral regurgitation (MR) due to abnormal chordae tendineae as a primary cause is rare. This clinicopathologic study included four such cases which occurred among 6,500 consecutive autopsies on persons older than 60 years. This paper describes three of these cases. Case 1 was a 76-year-old woman with congestive heart failure, MR and atrial fibrillation. She died of acute myocardial infarction. The heart weighed 360 g. Mitral regurgitation was caused by a thick and long abnormal chorda originating from the posteromedial papillary muscle and protruding into the atrial surface of the middle scallop of the posterior mitral leaflet associated with prolapsed anterior mitral leaflet. Case 2 was an 81-year-old woman with MR and congestive heart failure. She died of acute myocardial infarction. The heart weighed 480 g. There were abnormal chordae tendineae with very few branches at the posterior commissure. Parts of both mitral leaflets on the sides of posterior commissure were also prolapsed. Case 3 was a 91-year-old man with MR and atrial fibrillation. He died of congestive heart failure. The heart weighed 530 g. Abnormal chordae tendineae with reticular structures originated from the anterolateral papillary muscle and protruded into the anterior mitral leaflet, which induced severe MR. These cases had abnormally protruding chordae tendineae, abnormal branching, and abnormal structures of the chordae tendineae, respectively. These abnormal chordae tendineae were considered to be congenital anomalies. Clinically all patients had a holosystolic murmur (Levine III-IV degrees), refractory congestive heart failure and atrial fibrillation. The etiology of the MR in these three patients was suspected to be ruptured chordae tendineae demonstrated on echocardiograms. These patients had heavy hearts (mean 457 g) with enlarged left atria and thickened mitral valves, which corresponded to the appearance of severe MR.

Aged↗

PubMed1995

Analysis of small cystic lesions of the pancreas.

UNLABELLED: There have been few reports on (1) the nature and pathogenesis of small cystic lesions of the pancreas, (2) their incidence, age distribution, and location, and (3) their significance as potential precursors of intraductal papillary tumors, mucinous cystic tumors, and duct cell carcinomas. MATERIALS: Epithelial growth of small cystic lesions in 300 consecutive autopsy cases and in seven cases of small duct cell carcinoma from among 2300 elderly autopsy cases, was evaluated by histopathological analysis. One hundred eighty-six cystic lesions were found in 73 of 300 autopsy cases (24.3%). The incidence of cystic lesions increased with age. Cystic lesions were equally distributed throughout the pancreas. Epithelial atypia was histologically classified into five groups: normal epithelium; papillary hyperplasia without atypia; atypical hyperplasia; carcinoma in situ; and invasive carcinoma. The incidence of each group was 47.5, 32.8, 16.4, 3.4, and 0%, respectively. Epithelia of atypical hyperplasia or carcinoma in situ were more prevalent in small cystic lesions (less than 4 mm in diameter) than in larger lesions (chi-square test, p < 0.05). Epithelia of dilated ductular branches adjacent to cystic lesions showed a similar degree of atypia as the epithelia of the cystic lesions themselves (p < 0.01). Epithelial atypia of the main pancreatic duct was mild in all of the cases but two, and was not related to that of the cystic lesion. Among the seven cases of small duct cell carcinoma, two cases had small cancerous cystic lesions, 4.1 and 5.3 mm in diameter, within the tumor. Small cystic lesions appear to have the potential to progress to malignancy but definitive evidence has not been demonstrated. Additional studies, including molecular biological examinations, are necessary to fully understand the biology of these lesions.

Aged↗