Correlation of staining for LKB1 and COX-2 in hamartomatous polyps and carcinomas from patients with Peutz-Jeghers syndrome

Germline mutations of the LKB1 gene lead to Peutz-Jeghers syndrome (PJS), which is associated with a predisposition to gastrointestinal polyposis and cancer. In this study we tested for germline mutations of LKB1 in 11 patients with PJS from nine families and analyzed the expression patterns of the LKB1 and cyclo-oxygenase-2 (COX-2) proteins in 28 Peutz-Jeghers polyps (PJPs) and five carcinomas from these patients by immunohistochemical (IHC) analysis. In eight of those families we identified seven different mutations, which consisted of two splice site mutations, two nonsense mutations, one small in-frame deletion, one frame-shift mutation, and one silent mutation. Immunostaining revealed nuclear and cytoplasmic expression of LKB1 protein in 23 PJPs and five carcinomas, nuclear expression alone in one PJP, and loss of LKB1 protein expression in four PJPs, indicating a heterogeneous LKB1 expression pattern in PJPs. Overexpression of COX-2 was detected in 23 (82%) of 28 PJPs and in all carcinomas. Despite heterogeneity in staining of LKB1 among individuals and even among samples from the same individual, we found statistically significant correlations in staining of LKB1 relative to COX-2. These results suggest that COX-2 plays a role in tumorigenesis in PJS and may therefore be considered as a potential target for PJS chemoprevention.

An unusual admixture of neoplastic and metaplastic lesions of the female genital tract in the Peutz-Jeghers Syndrome

BACKGROUND

Peutz-Jeghers Syndrome (PJS) is a rare autosomal dominant condition with variable penetrance characterized by gastrointestinal hamartomatous polyps and mucocutaneous pigmentation. Patients with PJS have an increased risk for breast, gastrointestinal and female genital tract cancers.

CASE

Multiple genital tract neoplasms in a 41-year-old Italian woman with PJS are described. The patient presented with abdominal pain due to intussusception. A CT scan of the abdomen also showed a left adnexal mass, diagnosed as ovarian mixed serous and mucinous borderline tumor. An ovarian microscopic sex cord tumor with annular tubules (SCTAT) was incidentally diagnosed together with a minimal deviation mucinous adenocarcinoma of the uterine cervix. Also areas of typical hyperplasia of the tubal mucosa with mucinous metaplasia were found.

CONCLUSION

This appears to be one of the rare cases reported in literature in which PJS is complicated by multiple and contemporaneous genital tract tumors and rare histological findings. The clinical significance of recurrence of these unusual genital tract tumors and histological alterations in PJS patients is reviewed.

Preventive measures in Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a rare genetic disorder characterized by mucocutaneous melanin deposition, intestinal polyposis and an increased risk of cancer, both intestinal and extra-intestinal. We describe the current status of diagnosis and the methods by which the consequences of this condition can be minimized. A surveillance program for those diagnosed is also included.

[Peutz-Jeghers syndrome]

Peutz-Jeghers syndrome is an autonomic dominant disease characterized by hamartomatous polyps and mucocutaneous hyperpigmentation. We present 16 cases; females were more affected. The most common presenting complaints were of gastrointestinal tract. All polyps found were hamartomatous with general distribution through gastrointestinal tract. Endoscopic polypectomy should be carried out for treatment. Radiologic, endoscopic and histologic studies should be conducted for long-term follow-up, because of high risk of malignancy.

Gastrointestinal polyposis in childhood: clinicopathologic and genetic features

Gastrointestinal polyps and certain extraintestinal lesions in children may herald a hereditary polyposis syndrome, with an increased risk of neoplasia and other health problems for both children and their relatives. The availability of molecular/genetic screening tests has increased early diagnosis of younger members of known polyposis families. This article reviews the gross and microscopic features of polyposis syndromes of childhood and summarizes the molecular/genetic advances in this field. Clinical management is also briefly discussed.

Genetic screening for Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is clinically characterized by mucocutaneous melanocytic pigmentation, intestinal hamartomatous polyposis and a significantly increased risk of developing cancer. Mutations in the serine/threonine kinase (STK-)11 gene, also designated LKB1, are found in approximately 60% of cases of Peutz-Jeghers syndrome. There is evidence that genetic heterogeneity exists and gene(s) that have not yet been discovered may be responsible for the disease. Since most mutations in Peutz-Jeghers syndrome are null alleles and are dispersed throughout the entire STK11/LKB1 gene, the mutation screening strategies that combine approaches at both the DNA and RNA level are favored. Based upon the identification of novel mutational mechanisms, the impact of RNA-based screening for germinal STK11/LKB1 mutations in Peutz-Jeghers syndrome are specifically discussed.

Duodenal cancer in a patient with Peutz-Jeghers syndrome: molecular analysis

We experienced an unusual case of duodenal adenocarcinoma associated with Peutz-Jeghers syndrome (PJS). A 34-year-old woman was admitted to our hospital with abdominal pain. She had been diagnosed as having PJS at 21 years of age, based on the presence of mucocutaneous pigmentation of the lip and fingertips, and colonic hamartomatous polyps. Abdominal computed tomography revealed a tumor in the third portion of the duodenum extending into the pancreas head. As the tumor was pathologically determined to be adenocarcinoma at the time of surgery, pylorus-preserving pancreaticoduodenectomy was performed. We carried out molecular analyses of this patient to examine the pathway of carcinogenesis in PJS. The tumor did not show somatic mutation of the APC and K-ras genes, which is a critical step for the adenoma-carcinoma sequence in colon cancer. Importantly, a germline mutation of the STK11 gene was detected at codon 281 delC in exon 6. Moreover, the tumor showed loss of heterozygosity of the 19p marker near STK11 and somatic mutation of the p53 gene. These findings suggest that STK11 is a tumor suppressor gene regulating the development of hamartomas, and that somatic mutation of p53 subsequently promotes gastrointestinal cancer at a later stage in PJS.

Course and follow-up of solitary Peutz-Jeghers polyps: a case series

BACKGROUND AND AIMS

Peutz-Jeghers syndrome (PJS) is a rare, autosomal-dominant disease characterized by hamartomatous polyps of the alimentary tract, hyperpigmentation of the skin, and family history of PJS. Rarely, solitary Peutz-Jeghers polyps (PJP) arise in patients without other features of PJS.

PATIENTS AND METHODS

We reviewed eight patients since 1979 with solitary PJP, six men and two women.

RESULTS

The average age at diagnosis was higher (56+/-13 years) than that of PJS patients in the literature. Polyps were found in the sigmoid colon ( n=4), cecum ( n=1), stomach ( n=1), and duodenum ( n=2). The colonic polyps were diagnosed and removed endoscopically. Indications for colonoscopy included routine screening ( n=4) or rectal bleeding ( n=1). The duodenal and gastric polyps were diagnosed and removed during gastroduodenoscopic examinations, which were performed for nonspecific dyspepsia ( n=2) or gastrointestinal bleeding ( n=1). The median size was 20 mm (range 2 mm-25 mm). Patients were followed for a median of 11.5 years (range 3-22) without another PJP or cancer. Three patients died of causes unrelated to PJP. Five patients are alive and polyp free.

CONCLUSION

Solitary PJP do not carry a risk of gastrointestinal cancer and are not an indication for specific high-risk screening.

Clinicopathologic and molecular features of pancreatic adenocarcinoma associated with Peutz-Jeghers syndrome

Pancreatic cancer is increasingly prevalent and almost uniformly fatal. Studies of the molecular genetics of sporadic and hereditary cases of pancreatic cancer as well as the molecular biology of pancreatic development may advance our understanding of the mechanism underlying pathogenesis of this malignancy. Based on a case of pancreatic adenocarcinoma in a patient with Peutz-Jeghers syndrome (PJS), the clinicopathologic features and molecular genetics of pancreatic tumors associated with this hereditary cancer syndrome are reviewed. Particular emphasis is placed on the developmental roles and biochemical functions of STK11/LKB1, the gene mainly responsible for PJS. Modeling pancreatic cancer in animal models such as the mouse and zebrafish will further our understanding of the pathogenesis of this important disease, and the studies derived from these model organisms can be potentially applied for developing novel preventive and therapeutic strategies.

Premalignant conditions of the pancreas

Premalignant conditions of the pancreas include benign tumours of the pancreas, intraepithelial neoplasia arising within pancreatic ducts, and tumours of the neuroendocrine cells of the pancreas. In addition, there is a variety of rare genetic conditions that predispose to pancreatic exocrine malignancies such as Peutz-Jeghers syndrome, hereditary non-polyposis colorectal cancer syndrome, familial pancreatitis, germline BRCA2 mutations, and pancreatic endocrine malignancies such as type 1 neurofibromatosis (von Recklinghausen's disease) and multiple endocrine neoplasia type 1. More controversial is the concept of chronic pancreatitis and diabetes mellitus as conditions that increase the risk of pancreatic cancer. However, there is no doubt that smoking is a potentiating factor for pancreatic cancer, especially in people who have familial/genetic risk factors. This review will include the recently proposed new nomenclature and classification system for intraepithelial neoplasia in the pancreatic ducts, an overview of the various familial syndromes that are associated with an increased risk of pancreatic tumours, the surveillance programmes that have been introduced to monitor such families, and methods for early diagnosis.

Induction of cyclooxygenase-2 in a mouse model of Peutz-Jeghers polyposis

Inactivating germ-line mutations of LKB1 lead to Peutz-Jeghers syndrome (PJS). We have generated mice heterozygous for a targeted inactivating allele of Lkb1 and found that they develop severe gastrointestinal polyposis. In all cases, the polyps arising in the Lkb1+/- mice were found to be hamartomas that were histologically indistinguishable from polyps resected from PJS patients, indicating that Lkb1+/- mice model human PJS polyposis. No evidence for inactivation of the remaining wild-type Lkb1 allele in Lkb1+/- -associated polyps was observed. Moreover, polyps and other tissues in heterozygote animals exhibited reduced Lkb1 levels and activity, indicating that Lkb1 was haploinsufficient for tumor suppression. Analysis of the molecular mechanisms characterizing Lkb1+/- polyposis revealed that cyclooxygenase-2 (COX-2) was highly up-regulated in murine polyps concomitantly with activation of the extracellular signal-regulated kinases 1 and 2 (Erk1/2). Subsequent examination of a large series of human PJS polyps revealed that COX-2 was also highly up-regulated in the majority of these polyps. These findings thereby identify COX-2 as a potential target for chemoprevention in PJS patients.

Loss of the Lkb1 tumour suppressor provokes intestinal polyposis but resistance to transformation

Germline mutations in LKB1 (also known as STK11) are associated with Peutz-Jeghers syndrome (PJS), a disorder with predisposition to gastrointestinal polyposis and cancer. PJS polyps are unusual neoplasms characterized by marked epithelial and stromal overgrowth but have limited malignant potential. Here we show that Lkb1(+/-) mice develop intestinal polyps identical to those seen in individuals affected with PJS. Consistent with this in vivo tumour suppressor function, Lkb1 deficiency prevents culture-induced senescence without loss of Ink4a/Arf or p53. Despite compromised mortality, Lkb1(-/-) mouse embryonic fibroblasts show resistance to transformation by activated Ha-Ras either alone or with immortalizing oncogenes. This phenotype is in agreement with the paucity of mutations in Ras seen in PJS polyps and suggests that loss of Lkb1 function as an early neoplastic event renders cells resistant to subsequent oncogene-induced transformation. In addition, the Lkb1 transcriptome shows modulation of factors linked to angiogenesis, extracellular matrix remodelling, cell adhesion and inhibition of Ras transformation. Together, our data rationalize several features of PJS polyposis--notably its peculiar histopathological presentation and limited malignant potential--and place Lkb1 in a distinct class of tumour suppressors.

Two novel mutations and a new STK11/LKB1 gene isoform in Peutz-Jeghers patients

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disorder with variable expression and incomplete penetrance characterized by mucocutaneous pigmentation, predisposition to hamartomatous intestinal polyposis, and various other neoplasms. It occurs in approximately 1 in 8,300 to 29,000 live births. In nearly 50% of patients PJS is caused by germ line mutations in the STK11/LKB1 serine/threonine kinase gene, the only kinase gene currently known to act as a tumor suppressor. We have performed a mutation search in the STK11/LKB1 gene in 8 sporadic cases and 3 PJS families using a combination of different screening techniques. We have identified four mutations, two of which I177N and the IVS2+1A->G, were previously unreported. We have also evaluated the presence of cDNA alterations by means of RT-PCR analysis and direct cDNA sequencing and have found two aberrant transcripts in a single PJS case despite the lack of any apparent genomic alteration. Finally, we report the presence of a novel STK11/LKB1 cDNA isoform observed in all the normal subjects studied as well as in the majority of the PJS patients.

Gastrointestinal hamartomatous polyposis in Lkb1 heterozygous knockout mice

Peutz-Jeghers syndrome (PJS) is a hereditary disorder characterized by gastrointestinal hamartomatous polyposis associated with mucocutaneous pigmentation. Germ-line mutations of the gene encoding LKB1 (STK11), a serine/threonine kinase, are identified in most PJS patients. To investigate the role of LKB1 in the PJS phenotypes, we introduced a germ-line mutation in the mouse Lkb1 gene by homologous recombination in mouse embryonic stem cells. In most Lkb1 (+/-) mice >20 weeks of age, hamartomatous polyps developed in the glandular stomach, often in the pyloric region. Small intestinal hamartomas also developed in approximately one-third of the Lkb1 (+/-) mice >50 weeks of age. A genomic PCR and sequence analysis showed that all hamartomas retained both the wild-type and targeted Lkb1 alleles, indicating that allelic loss of the wild-type Lkb1 was not the cause of polyp formation. Moreover, the LKB1 protein level was not reduced in hamartomatous polyps compared with that in the Lkb1 (+/-) normal gastric mucosa. In addition, the remaining allele showed neither missense mutations in the coding sequence nor produced truncated LKB1 in the hamartoma. Taken together, these data suggest that the wild-type Lkb1 is expressed in the hamartoma at the haploid amount. Accordingly, the gastrointestinal hamartomas appear to develop because of the Lkb1 haploinsufficiency. Although additional genetic events may be critical in hamartoma and adenocarcinoma development, these data strongly suggest that the initiation of polyposis is not the result of loss of heterozygosity in Lkb1.

[Peutz-Jeghers syndrome. Two case reports]

The Peutz jeghers syndrome is a familial affection with dominant autosomic transmission characterized by a hamartoma digestive polyposis and a cutaneous mucous lentiginosis with periorifice predominance. This affection represented 3 into 10% for the familial polyps. The digestive polyps constitute the must important part of the pentz jeghers syndrome because they determined to only the clinic manifestation and the disease prognostic with there complications: intestinal invaginations, haemorrhage. In this work, we report two observations of patients presented a Peurtz Jeghers syndrome, and we determine, after literature review the epidemiologic, pathogenic, clinic, anatomy pathologic, prognosis and therapeutics of this effection.

Feminizing Sertoli cell tumor associated with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterized by the association of mucocutaneous pigmentation and multiple gastrointestinal hamartomatous polyps and with an increased risk of developing gonadal sex tumors besides other malignancies. We describe a 7 1/2 year-old boy with PJS and bilateral gynecomastia. He has had buccal pigmentation since 1.5 years and had been operated for rectal polyp excision at 3.5 years. On physical examination, his height was at the 90th percentile, and his height age and bone age were 9 and 10 1/2 years, respectively. Increased melanotic buccal pigmentation of the lips and bilateral gynecomastia were noticed. Both of the testes were firm, non-tender and smooth on the surface, and each measured 8 ml. Hormonal measurements were all in the prepubertal range. Testis ultrasonography showed bilateral hyperechogenic areas within the glands. When he was operated for invagination and an ileum segment full of polyps was resected, bilateral testicular biopsies were also performed. Histopathological evaluation of the testes revealed bilateral multicentric benign Sertoli cell tumors. The aromatase inhibitor testolactone was started to slow skeletal maturation. On the basis of this and previous reports, PJS associated with sex-cord tumors is increasingly recognized in males as well as in females.

[Unusual complications of the Peutz-Jeghers-syndrome in two consecutive generations of the same family]

The Peutz-Jeghers syndrome is an autosomal dominant inherited disease, characterized by the presence of hamartomatous polyposis of the gastrointestinal tract and perioral mucocutaneous pigmentation. The incidence of surgical complications in these patients is relatively rare, and correlates with the size and location of the polyps. We report on two complications of the Peutz-Jeghers syndrome which occurred in two generations of the same family. There was a perforation and an invagination of the small intestine. Both cases were treated by resection of the small intestine.

[Unusual complications of the Peutz-Jeghers-syndrome in two consecutive generations of the same family]

The Peutz-Jeghers syndrome is an autosomal dominant inherited disease, characterized by the presence of hamartomatous polyposis of the gastrointestinal tract and perioral mucocutaneous pigmentation. The incidence of surgical complications in these patients is relatively rare, and correlates with the size and location of the polyps. We report on two complications of the Peutz-Jeghers syndrome which occurred in two generations of the same family. There was a perforation and an invagination of the small intestine. Both cases were treated by resection of the small intestine.

Genetics of Peutz-Jeghers syndrome, Carney complex and other familial lentiginoses

Peutz-Jeghers syndrome (PJS, #175200) and Carney complex (CNC, OMIM#160980) are the two most common multiple neoplasia syndromes associated with lentiginosis. Both disorders are inherited in an autosomal dominant manner and they have recently been elucidated at the molecular level. PJS and CNC share manifestations with Cowden syndrome (or Cowden disease) (CS, OMIM#158350) and Bannayan-Riley-Ruvalcaba syndrome (BRR, OMIM#153480). The endocrine tumors of CS and PJS, which could classify these disorders as variant types of multiple endocrine neoplasias (MENs), are not present in most CS and BRR patients, but lentigines are shared by PJS, CNC and BRR. The serine-threonine kinase STK11 (or LKB1), located on 19p13, is mutated in more than half of all PJS kindreds. The R1alpha subunit of c-AMP-dependent protein kinase A, located on 17q22-24, is mutated in 40% of CNC kindreds. The protein phosphatase PTEN is mutated in most cases of CS and in almost 50% of BRR kindreds, despite significant clinical heterogeneity in these syndromes. The molecular elucidation of the lentiginoses and their related syndromes identifies new pathways of growth control and cellular regulation that are important for endocrine signaling, tumorigenesis, cutaneous function and embryonic development.

STK11/LKB1 Peutz-Jeghers gene inactivation in intraductal papillary-mucinous neoplasms of the pancreas

Despite the growing awareness of intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas among clinicians, the molecular features of IPMNs have not been well characterized. Previous reports suggest that inactivation of the STK11/LKB1, a tumor-suppressor gene responsible for Peutz-Jeghers syndrome (PJS), plays a role in the pathogenesis of gastrointestinal hamartomas as well as several cancers, including pancreatic adenocarcinoma. Using polymerase chain reaction amplification of five microsatellite markers from the 19p13.3 region harboring the STK11/LKB1 gene, we analyzed DNA from 22 IPMNs for loss of heterozygosity (LOH). LOH at 19p13.3 was identified in 2 of 2 (100%) IPMNs from patients with PJS and 5 of 20 (25%) from patients lacking features of PJS (7 of 22, 32% overall). Sequencing analysis of the STK11/LKB1 gene in these IPMNs with LOH revealed a germline mutation in one IPMN that arose in a patient with PJS and a somatic mutation in 1 of the 20 sporadic IPMNs. None of the 22 IPMNs showed hypermethylation of the STK11/LKB1 gene. These results suggest that the STK11/LKB1 gene is involved in the pathogenesis of some IPMNs.

A solitary gastric Peutz-Jeghers type polyp: report of a case

Peutz-Jeghers type polyps of the stomach are rare and almost always associated with intestinal polyposis and mucocutaneous pigmentation; a condition known as Peutz-Jeghers syndrome. The case presented in this report refers to a woman found to have a large solitary Peutz-Jeghers type polyp of the stomach, with a maximal diameter of 7cm. Extended investigation did not reveal intestinal polyposis or any other sign of Peutz-Jeghers syndrome. Because of the size of the polyp, a partial gastrectomy was performed. To the best of our knowledge, there are only three other reports in the literature of a solitary Peutz-Jeghers type gastric polyp occurring in the absence of Peutz-Jeghers syndrome. This patient is scheduled to undergo a follow-up examination every 2 years to detect any sign of the development of Peutz-Jeghers syndrome or malignancies commonly associated with it.

Sertoli cell proliferations of the infantile testis: an intratubular form of Sertoli cell tumor?

We report on six boys with intratubular Sertoli cell proliferations (ISCPs), studied by routine histologic methods, electron microscopy, and immunohistochemistry of anti-müllerian hormone (AMH), inhibin alpha-subunit, 3beta-hydroxysteroid dehydrogenase (3beta-HSD), proliferative cellular nuclear antigen, and p53, and carefully followed for extended periods with periodic clinical examinations, testicular ultrasonographies, and determinations of serum levels of AMH and inhibin B. Peutz-Jeghers syndrome was found in four of six patients, and gynecomastia occurred in five of six patients. One boy had isosexual pseudoprecocity. ISCPs were observed as multiple foci of seminiferous tubules with large and proliferated Sertoli cells replacing germ cells and limited by the basement membrane. Mitotic figures, atypia, and/or interstitial invasion were not observed. Bilateral ISCPs were the only pathologic finding in three patients (patient nos. 1-3) and were associated with a microscopic tumor that resembled a large-cell calcifying Sertoli cell tumor (LCCSCT) in a fourth patient (patient no. 4). In the two remaining patients (patient nos. 5 and 6) ISCPs and LCCSCT were found in both testes. Ultrastructural examination showed large Sertoli cells, with round nuclei, sparse organelles, and some glycogen. Inhibin alpha-subunit immunolocalization was positive in the five patients in whom it was determined (patient nos. 2-6), AMH was positive in those ISCPs associated with tumors (patient nos. 4-6) and negative in isolated ISCPs (patient nos. 2 and 3); 3beta-HSD and PCNA were variable, and p53 was negative in all ISCPs. Patient nos. 1-4 have been followed for 2-19 years. One of them is currently entering puberty, the other two have already completed puberty and have testes of normal size, and the remaining one is an adult with clinically normal testes and sperm production. None of these patients had evidence of tumor development during follow-up as shown by serial ultrasonographies and serum levels of AMH and inhibin B. Patient nos. 5 and 6 who had bilateral ISCPs and LCCSCT were orchidectomized and evolved for 2-10 years after surgery without tumor recurrence. The prognostic significance of ISCPs, particularly when they are the only pathologic finding in a testicular biopsy, is a matter of controversy. Based on the long normal evolution, we recommend a conservative approach to therapy. The bilateral and multicentric character of ISCPs and their association with Sertoli tumors and Peutz-Jeghers syndrome suggest that they represent either proliferative lesions with tumorigenic potential or the intraepithelial stage in the evolution of some testicular Sertoli cell tumors.

The Peutz-Jegher gene product LKB1 is a mediator of p53-dependent cell death

Here, we investigate the mechanism and function of LKB1, a Ser/Thr kinase mutated in Peutz-Jegher syndrome (PJS). We demonstrate that LKB1 physically associates with p53 and regulates specific p53-dependent apoptosis pathways. LKB1 protein is present in both the cytoplasm and nucleus of living cells and translocates to mitochondria during apoptosis. In vivo, LKB1 is highly upregulated in pyknotic intestinal epithelial cells. In contrast, polyps arising in Peutz-Jegher patients are devoid of LKB1 staining and have reduced numbers of apoptotic cells. We propose that a deficiency in apoptosis is a key factor in the formation of multiple benign intestinal polyps in PJS patients, and possibly for the subsequent development of malignant tumors in these patients.

Lentigo

A lentigo is a small pigmented macule with a sharply circumscribed border. There are multiple clinical and etiologic forms. Lentigines are often initially identified shortly after birth, although they may appear later in childhood. Certain varieties are associated with systemic abnormalities. Histologic findings include epidermal hyperplasia with increased pigmentation of the basal layer.

Somatic mutations of LKB1 and beta-catenin genes in gastrointestinal polyps from patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is characterized by multiple gastrointestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer, mainly in the gastrointestinal tract. We examined mutations of the LKB1, beta-catenin, APC, K-ras, and p53 genes in 27 gastrointestinal hamartomatous polyps from 10 patients in nine PJS families. Of these hamartomatous polyps, one intestinal polyp had an adenomatous lesion, and one gastric polyp contained adenomatous and carcinomatous lesions. Germ-line mutations of the LKB1 gene were detected in six PJS families. Somatic mutations of the LKB1 gene were found in 5 polyps, whereas loss of heterozygosity (LOH) at the LKB1 locus at 19p was seen in 14 other polyps. In adenomatous lesions microdissected from hamartomatous polyps, both beta-catenin mutation and 19p LOH were detected. Furthermore, a carcinomatous lesion in a gastric hamartomatous polyp was found to contain a mutation of the p53 gene and LOH at the p53 locus in addition to LOH at the LKB1 locus and a beta-catenin mutation. K-ras mutations were detected in a few polyps, whereas no APC mutation or 5q LOH was detected in hamartomatous polyps. These results suggest that gastrointestinal hamartomatous polyps in PJS patients develop through inactivation of the LKB1 gene by germ-line mutation plus somatic mutation or LOH of the unaffected LKB1 allele, and that additional mutations of the beta-catenin gene and p53 gene convert hamartomatous polyps into adenomatous and carcinomatous lesions.

[Peutz-Jeghers syndrome]

Peutz-Jeghers syndrome(PJS) is an autosomal dominant disease which is characterized by melanin spots on lips and buccal mucosa, and multiple gastrointestinal hamartomatous polyps. Patients are at risk of forming carcinomas in the gastrointestinal tract, uterus, ovary, breast and other organs. The LKB1(STK11) gene at chromosome 19p13.3 has been identified in 1998 as the causative gene for PJS, and germline mutations of this gene have been detected in about 50 PJS families. These mutations include nonsense mutations, frameshift mutations and missense mutations, all of which are assumed to inactivate the LKB1 gene. LKB1 gene appears to be a tumor suppressor gene, and inactivation of this gene through germline mutation and loss of normal allele may develop hamartomatous polyps. However, the function of LKB1 and mechanism of carcinoma formation are still unclear.

[Patient with Peutz-Jeghers syndrome and liver metastases from an unknown primary tumor]

In a 35-year old man with deep venous thrombosis liver metastases of an adenocarcinoma were observed. The primary tumour was not found. The patient had pigmentations on the lips and hamartomatous polyposis of the intestine. These findings indicate Peutz-Jeghers syndrome. In this syndrome there is an increased risk of, notably, gastrointestinal malignancy at an early age. Recent investigations have shown that Peutz-Jeghers syndrome is associated with a mutation in the STK11 gene on chromosome 19.

Misplacement of dysplastic epithelium in Peutz-Jeghers Polyps: the ultimate diagnostic pitfall?

Peutz-Jeghers syndrome is characterized by multiple polyps throughout the gastrointestinal tract in association with mucocutaneous pigmentation. Small bowel polyps in the syndrome may exhibit epithelial misplacement, into the submucosa, the muscularis propria, and even the subserosa. The authors demonstrate two patients in whom there is also misplacement of dysplastic epithelium into the submucosa and muscularis propria of the small bowel. Epithelial misplacement is recognized to mimic invasive malignancy. Such mimicry is heightened substantially when the misplaced epithelium is dysplastic. Correct interpretation of the histologic changes is aided by the use of special stains, which demonstrate the associated lamina propria and the lack of a desmoplastic response, and immunohistochemistry, which shows that the misplaced dysplastic epithelium is accompanied by non-neoplastic mucosa. There is an increased prevalence of gastrointestinal malignancy in Peutz-Jeghers syndrome. However, the presence of perplexing histologic features, caused by epithelial misplacement, especially when some of that epithelium is dysplastic, in small bowel polyps at least has the potential for the overdiagnosis of malignancy in the syndrome.

Efficacy of magnifying endoscopy in the differential diagnosis of neoplastic and non-neoplastic polyps of the large bowel

PURPOSE

We have introduced magnifying colonoscopy into clinical practice and analyzed its diagnostic efficacy, especially regarding the ability to distinguish neoplastic from non-neoplastic polyps.

METHODS

The materials consisted of 923 polyps. After identifying the lesions during normal colonoscopy, a dye was sprayed, and then the zoom apparatus of the colonoscope was used to make a magnified observation at a maximum 100 times magnification. We classified the crypt orifices into six categories and labeled them A to F as follows: A, a medium round appearance; B, an asteroid appearance; C, an elliptic appearance; D, a small, round appearance; E, a cerebriform appearance; F, no apparent structural appearance.

RESULTS

Forty-two of 923 polyps did not reveal any clear images of crypt patterns. The percentage of histologically neoplastic change in the lesions classified as A, B, C, D, E, and F were 10, 15.9, 93.7, 100, 94.8, and 87.5 percent, respectively. When we considered types A and B to represent a crypt pattern of non-neoplastic lesions, and types C, D, E, and F to represent neoplastic lesions, and when the lesions that did not show any clear images were classified as a misjudgment, the diagnostic accuracy of neoplastic lesions (sensitivity) was 92 percent and that of non-neoplastic lesions (specificity) was 73.3 percent. Overall, the diagnostic accuracy in differentiating neoplastic from non-neoplastic lesions was 88.4 percent. Twenty-three neoplastic lesions that were misjudged to be non-neoplastic were histologically adenoma with mild atypia in 22 and adenoma with moderate atypia in 1.

CONCLUSION

Magnifying colonoscopy was considered to be useful in determining the indications for colonoscopic removal.

Sporadic Peutz-Jeghers syndrome in a Nigerian

Peutz-Jeghers syndrome is a rare condition of muco-cutaneous pigmentation and polyposis of the gut. Reports of its occurrence from the Black world have been infrequent. A case is presented of an 18 year old Nigerian girl with pigmentation of the inner lips and soles of both feet, and recurrent attacks of abdominal pain necessitating two surgical procedures for intestinal obstruction with removal, in both cases, of polyps. Problems of complications and therapeutic modalities are discussed.

Overexpression of epidermal growth factor receptor in Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is characterized by gastrointestinal hamartomatous polyposis, mucocutaneous pigmentation, and a predisposition to cancer. The etiology of this syndrome is unknown. We investigated the expression of epidermal growth factor receptor (EGFr), transforming growth factor-alpha (TGF-alpha), transforming growth factor-beta1 (TGF-beta1) and transforming growth factor-beta receptor (TGF-beta RII) between normal and Peutz-Jeghers small bowel tissues. In addition, immunoprecipitation by phosphotyrosine antibodies followed by EGFr western blotting was measured and compared between a Peutz-Jeghers hamartoma and normal duodenal tissue. EGFr expression was increased 2.5-fold in normal and hamartomatous tissue of Peutz-Jeghers patients compared to normal small bowel tissue. In Peutz-Jeghers tissues, the major EGFr immunoreactive band was increased size from 170 to approximately 200 kDa. Using an antibody specific for activated EGFr, this larger size band was predominant in Peutz-Jeghers tissue. Immunoprecipitation of a hamartoma by a phosphotyrosine specific antibody followed by western blotting for EGFr demonstrated this 200-kDa band. Expression of TGF-alpha, TGF-beta1, TGF-beta1 RII was not significantly different between normal and Peutz-Jeghers tissues. In conclusion, EGFr was overexpressed in normal and hamartomatous small bowel tissue of Peutz-Jeghers patients, which suggests that EGFr in Peutz-Jeghers tissue is persistently activated or highly stimulated by endogenous ligands and also suggests a possible role for EGFr in the pathogenesis of Peutz-Jeghers syndrome.

Allelic imbalance at the LKB1 (STK11) locus in tumours from patients with Peutz-Jeghers' syndrome provides evidence for a hamartoma-(adenoma)-carcinoma sequence

Patients with Peutz-Jeghers' syndrome (PJS) develop hamartomatous gastrointestinal polyps and characteristic pigmentation, as a result of germline mutations in the LKB1 gene. The hamartomas in PJS were long considered to be without malignant potential. There is, however, accumulating epidemiological evidence to suggest that PJS predisposes to cancers at several different sites (colon, pancreas, breast, ovary, testis, and cervix), although large enough patient samples are rarely available to prove this. Allelic imbalance [allele loss, loss of heterozygosity (LOH)] has previously been reported in a small number of PJS polyps, suggesting that LKB1 acts as a tumour suppressor in these tumours. This study confirms allelic loss at LKB1 in PJS polyps and shows that LOH also occurs in cancers of the colon, breast, and cervix in PJS patients. Allele loss was additionally found in a colonic adenoma from a PJS patient, strongly suggesting the existence of a hamartoma-(adenoma)-carcinoma sequence in tumourigenesis. These results provide molecular evidence that PJS patients are predisposed to cancers at several sites, as a direct result of selection for loss of the 'wild-type' LKB1 allele in tumours. Given the rare involvement of LKB1 in sporadic cancers, these data also suggest that the indirect effect on cancer risk (or 'bystander effect') proposed for hamartomas in juvenile polyposis does not apply to carcinomas in PJS.

Polyps as biomarkers for colorectal neoplasia

Current understanding of colorectal carcinogenesis suggests a series of genetic changes occurring pari passu with morphological changes ultimately resulting in a cancerous lesion. The adenomatous polyp was originally the prototype of the preneoplastic lesion but recently, other colonic polyps, primarily the hamartomas, have been clinically characterized as colorectal cancer biomarkers with genetic changes found mainly in the mesenchymal component as opposed to the ectodermal, or epithelial element. This, with the current interest in angiogenesis playing a role in the propagation of neoplastic lesions, has now encompassed every tissue element and opened the way for an understanding of the oncogenic process. This has suggested that considerable interaction occurs between all tissue elements, including what was previously described as epithelial-matrix interactions. While hyperplastic polyps are thought not to confer risk for cancer, they may offer clues as to the first steps of the overall process. Microadenomas have introduced new clinical as well as biological considerations, as unique risk factors. Investigation of these lesions has moved from purely morphological correlations to mechanistic dissections of important biological pathways using both genetic and protein chemistry tools. This review explores the microcosm of the colonic polyp and its relation to cancer as the quintessential premalignant biomarker.

Peutz-Jeghers syndrome: a new understanding

Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction and bleeding. Furthermore, repeated operations may be needed in some patients, which may result in short bowel syndrome. Although early reports did not demonstrate a predisposition to cancer in patients with this syndrome, more recent studies have described an increased risk for both gastrointestinal and extra-gastrointestinal cancers. Women with the Peutz-Jeghers syndrome have the extremely high risk for breast and gynecologic cancer. Recently, Peutz-Jeghers syndrome susceptibility gene, encoding the serine threonine kinase STK11 (also called LKB1), was identified in families with Peutz-Jeghers syndrome. The identifications of germline mutations in families with Peutz-Jeghers syndrome could be a turning point in the management of Peutz-Jeghers syndrome.

The usefulness of intra-operative endoscopy in Peutz-Jeghers syndrome: a case report

The Peutz-Jeghers syndrome is an autosomal dominant inherited disease manifested by a combination of mucocutaneous pigmentation and gastrointestinal hamartomatous polyps that usually cause intussusception and intestinal hemorrhage. We report a case in which the patient has been followed-up on for 14 years and who underwent surgical and endoscopic polyp removal several times as well as one intestinal resection. This time, with the use of combined surgery and perioperative endoscopy, 27 polyps were removed, performing only 3 enterotomies. This is the highest number in one session to be reported in the literature. The usefulness of this technique is providing a "clean small intestine" that allows the patient a longer time interval between laparotomies and reduces the complications associated with multiple laparotomies and resections.

Histochemical study of apoptosis and cell proliferation in hereditary intestinal diseases

The occurrence of apoptosis and cell proliferation in hereditary intestinal diseases was analyzed for possible diagnostic markers that could discriminate the formation of tumors that would develope into cancer. In all, 15 adenomas in familial adenomatous polyposis, 3 juvenile polyposis, 5 Peutz-Jeghers syndrome, 14 sporadic adenomas, and 46 colorectal carcinomas were investigated. Tissue specimens were examined for apoptotic cells by TdT-mediated dUTP-biotin nick end labeling (TUNEL), and proliferating cells by immunohistochemistry of proliferating cells nuclear antigen (PCNA). In hereditary intestinal diseases, the apoptotic and proliferating indexes were significantly lower than those in colorectal carcinoma, and higher apoptotic and proliferating indexes were observed in poorly differentiated colorectal adenocarcinoma and in subserosal stages of invasion. There were no significant differences in proliferating and apoptotic indexes between adenoma in FAP and sporadic adenoma. No apoptotic and proliferating cells were observed in juvenile polyposis, and only occasional proliferating cells were seen in Peutz-Jeghers syndrome. These findings demonstrated that TUNEL and PCNA staining are useful in correctly reflecting disease progression in hereditary intestinal diseases.

Colon polyps

Colon polyps may be single or multiple, noninherited or inherited, histologically may vary from inflammatory, hamartomatous, neurogenic, or adenomatous, and may be benign or malignant. The various recognized syndromes are discussed including their clinical presentation, malignant potential, and associated tumors. Recognition of these clinical syndromes will allow the clinician to categorize the patient and the relative risk. The discussion goes into the genetic studies identifying the adenomatous polyposis coli gene on chromosome 5 q21 and the identification of mutations arising in the DNA repair genes (MSA2, MLH1, PMSI, and M52) in the HNPCC syndrome. This identified two divergent pathologies, both involving "multiple hits" with mucosal cells going from normal to adenoma-dysplasia-carcinoma. The understanding of the multiple hit concept with the adenoma-dysplasia-carcinoma progression will aid in the further understanding of the broad neoplastic process.