Turcot's syndrome. A review

Medulloblastomas associated with an APC germline pathogenic variant share the good prognosis of CTNNB1-mutated medulloblastomas

BACKGROUND

Medulloblastomas may occur in a predisposition context, including familial adenomatosis polyposis. Medulloblastomas related to a germline pathogenic variant of adenomatous polyposis coli (APC) remain rare and poorly described. Their similarities with sporadic WNT medulloblastomas still require description.

METHODS

We performed a multicentric retrospective review of 12 patients treated between 1988 and 2018 for medulloblastoma with an identified or highly suspected (personal or familial history) APC germline pathogenic variant. We report personal and familial history APC gene pathogenic variants whenever available: clinical and histologic characteristics of the medulloblastoma, treatments, and long-term outcome, including second tumor and late sequelae.

RESULTS

Medulloblastomas associated with APC pathogenic variants are mainly classic (11/11 patients, 1 not available), nonmetastatic (10/12 patients) medulloblastomas, with nuclear immunoreactivity for ß-catenin (9/9 tested cases). Ten of 11 assessable patients are disease free with a median follow-up of 10.7 years (range, 1-28 y). Secondary tumors included desmoid tumors in 7 patients (9 tumors), 1 thyroid carcinoma, 2 pilomatricomas, 1 osteoma, 1 vertebral hemangioma, and 1 malignant triton in the radiation field, which caused the only cancer-related death in our series.

CONCLUSIONS

Medulloblastomas associated with an APC pathogenic variant have an overall favorable outcome, even for metastatic tumors. Yet, long-term survival is clouded by second tumor occurrence; treatment may play some role in some of these second malignancies. Our findings raise the question of applying a de-escalation therapeutic protocol to treat patients with APC germline pathogenic variants given the excellent outcome, and reduced intensity of craniospinal irradiation may be further evaluated.

Partial duplication of MSH2 spanning exons 7 through 14 in Lynch syndrome

BACKGROUND

Lynch syndrome, also referred to as hereditary nonpolyposis colorectal cancer, is the most common form of hereditary colorectal cancer, and is associated with a high incidence of multiple primary neoplasms in various organs.

METHODS

A 79-year-old woman (patient 1) diagnosed with ascending colon cancer had a history of previous carcinomas of the uterus, stomach, uroepithelial tract, and colon. One year later, she developed a brain tumor (glioblastoma). A 54-year-old female (patient 2) was diagnosed with endometrial cancer and sigmoid colon cancer. Both patients underwent genetic evaluations independently.

RESULTS

No mutations were found in an exon-by-exon analysis of genomic DNA by polymerase chain reaction (PCR) and reverse transcription (RT)-PCR. However, multiplex ligation-dependent probe amplification (MLPA) identified genomic duplication spanning from exon 7 to exon 14 of the MSH2 gene in both patients. Due to the presence of this characteristic gene duplication, their pedigrees were investigated further, and these showed that they are paternal half-sisters, consistent with paternal inheritance.

CONCLUSION

Large genomic duplication from intron 6 through intron 14 in MSH2 is a very rare cause of Lynch syndrome and is difficult to identify with conventional methods. MLPA may be an alternative approach for detecting large-scale genomic rearrangements.

Turcot syndrome in an elderly adult

A 67-year-old woman presented with hematochezia and an episode of transient expressive dysphasia. She was found to have multiple colonic polyps with adenocarcinomatous changes. Computed tomography brain scan and computed tomography-guided biopsy revealed a left frontoparietal glioblastoma multiforme. This case illustrates the rare presentation of Turcot syndrome-a hereditary colorectal polyposis syndrome-in an older adult.

Turcot syndrome with colonic obstruction and small intestinal invagination: report of a case

We report herein the case of a 16-year-old boy diagnosed as having Turcot syndrome, otherwise known as glioma-polyposis syndrome. The patient was transferred from the Department of Neurosurgery where he was undergoing investigation of a brain tumor, to the Department of Medicine for investigation of gastrointestinal symptoms. The patient was diagnosed as having Turcot syndrome, and was then transferred to the Department of Surgery for treatment of an obstruction in the sigmoid colon and small intestinal invagination. A subtotal colectomy with side-to-end ileoproctostomy and release of the invaginations was carried out. Multiple polyps were found in the colon, two of which, including a large polyp that obstructed the colonic lumen, were confirmed histologically to be adenocarcinoma. The remaining polyps were adenomas. A biopsy of the brain tumor confirmed a diagnosis of astrocytoma (WHO grade II). This case report describes the characteristic features of Turcot syndrome presented by this patient.

A father and son with Turcot's syndrome: evidence for autosomal dominant inheritance: report of two cases

Typical Turcot's syndrome is characterized by the association of a brain glioma together with multiple colonic polyposis, in which the number of polypoid lesions is small and the association of colonic cancer occurs at a younger age than in familial adenomatous polyposis. We describe a family in which both the father and his son presented with typical Turcot's syndrome without parental consanguinity. This is the first report of a family that is considered to follow an autosomal dominant inheritance. After reviewing 25 documented cases in which the average age of death was 20.3 years old, it was learned that the major cause of death was brain tumor (76 percent) and the minor cause was colon cancer (16 percent). Patients were very young and, therefore, unlikely to have produced a child before their death. These facts seem to support the theory that Turcot's syndrome is an autosomal dominant disorder.

Case report: an inherited APC mutation in the first reported Australian case of Turcot's syndrome

The objective of this study was to determine the inherited gene mutation responsible for the first reported Australian case of Turcot's syndrome. DNA was extracted from the archival tissue blocks obtained at the time of the patient's original surgery and from fresh blood samples obtained from selected family members. These were analysed for mutations of the familial adenomatous polyposis gene (APC). Analysis of DNA from the archival blocks and from each of the affected family members revealed an inherited 5 base pair deletion at codon 1061 of APC. In this case, the central nervous system tumour represents an extracolonic manifestation of familial adenomatous polyposis. The underlying inherited mutation of APC has been identified. In some cases of Turcot's syndrome, other genes appear to be involved. Recent literature examining the molecular basis of Turcot's syndrome is reviewed.

Malignant ependymomas in a patient with Turcot's syndrome: case report and management guidelines

BACKGROUND

Turcot's Syndrome is the association of multiple adenomatous polyps of the colon with a primary tumor of the central nervous system. We present the first reported case of Turcot's Syndrome in a patient with malignant ependymomas. Recent advances in the elucidation of the genetic basis for the hereditary forms of colon cancer have provided a clearer understanding of the etiology of Turcot's Syndrome. This new information is relevant to the neurosurgical community and provides updated guidelines in the diagnosis and management of patients with this complex disease process.

RESULTS

Turcot's Syndrome is related to two distinct genetic errors. The first involves a germ-line mutation in the adenomatous polyposis coli (APC) gene, which is postulated to act as a tumor suppressor gene. The second is a germ-line defect in one of a group of genes responsible for DNA nucleotide mismatch repair.

CONCLUSION

The elucidation of the gene defects responsible for the hereditary forms of colon cancer has provided a clearer understanding of the molecular basis of Turcot's Syndrome. Patients with hereditary forms of colon cancer and neurologic symptoms require immediate and thorough investigation because of their significantly increased risk of developing CNS tumors. Previously healthy patients diagnosed with a CNS tumor with a family history of adenomatous polyposis coli should undergo screening and surveillance colonoscopy as the CNS lesion may precede colonic symptoms. CNS screening guidelines for asymptomatic patients with adenomatous polyposis coli requires further risk analysis studies. All patients diagnosed with Turcot's Syndrome should be tested for the gene defect, including the CNS tumor tissue to provide further data on the genetic relationship between Turcot's Syndrome and the hereditary forms of colon cancer.

Genetic alterations in a patient with Turcot's syndrome

Turcot's syndrome (TS) is a rare disorder associated with the development of both brain and colon neoplasms. Because of the very low incidence of the disease, its molecular basis remains unclear. Presented is a TS case of a 30-year-old Japanese male with a histopathologically confirmed diagnosis of both brain tumor (glioblastoma multiforme) and colon tumor (well-differentiated adenocarcinoma). Germline mutations of the p53 gene, somatic mutations of the Ki-ras, p53 and APC genes, and microsatellite instability (MSI) was examined using polymerase chain reaction (PCR)-single strand conformation polymorphism analysis, followed by PCR-direct sequencing, and sequencing after subcloning. No germline mutations of the p53 gene were found. Somatic mutations of Ki-ras and APC genes were found in the colon adenocarcinoma but not in the brain tumor. No somatic mutation of the p53 gene was present in either colon or brain tumors. Microsatellite instability of both colon and brain tumors was positive in two of four loci. These results indicate that the colon tumor of the TS patient carries the Ki-ras and APC gene mutations. The finding of MSI in both the brain and the colon tumors may support the hypothesis that alterations of DNA repair genes are involved in the tumor development of the TS patient.

Molecular advances in the etiology and treatment of colorectal cancer

The diagnosis and treatment of colorectal cancer remains a formidable health care problem. Colorectal cancer is the second most frequently diagnosed cancer in both men and women in Western countries and accounts for over 55,000 deaths annually in the United States alone. Cancer of the colon and rectum is eminently curable by surgical resection if identified early; however, despite our best efforts, patient survival from this disease has changed little over the past 50 years. With the advent of molecular and genetic techniques, a number of novel discoveries have been made in the last decade which have greatly expanded our understanding of the etiology and cellular mechanisms contributing to the development and subsequent progression of colorectal cancer. This review summarizes the recent molecular advances in the understanding of both familial (HNPCC and FAP) and sporadic colorectal cancers. The numerous scientific advances described in this review offer the promise of the development of novel chemotherapeutic agents, more accurate prognostic indicators and better screening techniques.

Multiple ependymomas in a patient with Turcot's syndrome

A 21-year-old woman was diagnosed with Turcot's syndrome (TS) at age 16 years. She had two ependymomas, one was located in the left middle cerebellar peduncle and the other in the low sacral spinal canal. Her mother and brother both had colectomies for colonic polyposis. Her maternal uncle and grandfather also had this disease and both died from cancer of the colon in their fourth decade of life. The patient was found to have hyperpigmented spots in the retina, skull osteomas and normal neurological examinations. The bone scan and CSF were normal and she had a germline mutation in the segment 3 of the adenomatous polyposis coli (APC) gene. Following partial resection of the two ependymomas, she was treated with radiation and chemotherapy. One year after surgery, paraspinal desmoid tumors were found and removed. She is presently 42 months postsurgical resection of the neural tumors and has remained central nervous system tumor-free. The occurrence of multiple ependymoma in TS has not been reported, and the control of this patient's ependymomas is consistent with other reports of long-term survival with TS and glial tumors.

Polyposis coli, craniofacial exostosis and astrocytoma: the concomitant occurrence of the Gardner's and Turcot syndromes

BACKGROUND

Up to 60% of the patients with known adenomatous polyposis coli may present hyperostosis of the skull and facial bones, and/or a susceptibility to fibromas. This is known as the Gardner's syndrome, and is considered as an allelic variant of familial adenomatous polyposis (FAP). Also, although very rare, an adenomatous polyposis coli may occur with malignant tumors of the central nervous system, known as Turcot syndrome. If both syndromes are different phenotypic presentation of FAP, this would explain a simultaneous occurrence.

METHOD

We report the history of a patient who showed clinical signs of the simultaneous occurrence of both Gardner's and Turcot syndromes. The syndromes are compared, and in view of the literature, a genetic explanation for the concomitant occurrence is discussed.

RESULTS

Evidence obtained from the literature to consider Turcot syndrome as a phenotype of FAB is as follows: (1) The occurrence of Gardner's and Turcot syndromes in one family, but in different members; (2) The presence of congenital hypertrophic retinal pigmented epithelium (CHRPE), which correlates with the expression of polyps in FAP patients, in both syndromes; (3) Linkage of the Turcot phenotype to the adenomatous polyposis coli locus by genetic markers. Evidence obtained from this case report indicates that there is a manifestation of both syndromes in one patient together with a positive family history for FAP.

CONCLUSION

This concomitant occurrence of both Gardner's and Turcot syndromes in one patient clinically supports genetic and ophthalmic investigation to consider Turcot syndrome (like Gardner's syndrome) as a phenotypic variant of FAP. Patients with FAP should be examined for the presence of Gardner's syndrome. In case a Gardner's syndrome is suspected, a computed tomography scan of the brain is recommended because of the possible existence of a simultaneous Turcot syndrome.

The molecular basis of Turcot's syndrome

BACKGROUND

Turcot's syndrome is characterized clinically by the concurrence of a primary brain tumor and multiple colorectal adenomas. We attempted to define the syndrome at the molecular level.

METHODS

Fourteen families with Turcot's syndrome identified in two registries and the family originally described by Turcot and colleagues were studied. Germ-line mutations in the adenomatous polyposis coli (APC) gene characteristic of familial adenomatous polyposis were evaluated, as well as DNA replication errors and germline mutations in nucleotide mismatch-repair genes characteristic of hereditary nonpolyposis colorectal cancer. In addition, a formal risk analysis for brain tumors in familial adenomatous polyposis was performed with a registry data base.

RESULTS

Genetic abnormalities were identified in 13 of the 14 registry families. Germ-line APC mutations were detected in 10. The predominant brain tumor in these 10 families was medulloblastoma (11 of 14 patients, or 79 percent), and the relative risk of cerebellar medulloblastoma in patients with familial adenomatous polyposis was 92 times that in the general population (95 percent confidence interval, 29 to 269; P < 0.001). In contrast, the type of brain tumor in the other four families was glioblastoma multiforme. The glioblastomas and colorectal tumors in three of these families and in the original family studied by Turcot had replication errors characteristic of hereditary nonpolyposis colorectal cancer. In addition, germ-line mutations in the mismatch-repair genes hMLH1 or hPMS2 were found in two families.

CONCLUSIONS

The association between brain tumors and multiple colorectal adenomas can result from two distinct types of germ-line defects: mutation of the APC gene or mutation of a mismatch-repair gene. Molecular diagnosis may contribute to the appropriate care of affected patients.

Turcot's syndrome: a new case in the first decade of life

A case of Turcot's syndrome is described in an 8-year-old girl. Turcot's syndrome is a rare hereditary disease in which malignant glioma of the central nervous system is associated with colonic polyposis. The patient initially presented with a left parietal glioblastoma diagnosed by computed tomography (CT), and was subsequently found to have nonfamilial colonic polyposis.

Genetics of colon cancer: impact of inheritance on colon cancer risk

The genes that are mutated in two of the rare syndromes of hereditary colon cancer were recently identified, and genetic diagnosis is already possible in some cases. Acquired mutations of these same genes also appear to be important in sporadic colon cancers. Familial clustering of sporadic cases is common and may likewise arise from inherited susceptibility. Screening strategies for both the rare syndromes and the common cases of colon cancer with familial risk have been suggested. Certain clinical features allow stratification of colon cancer risk among common cases. It is anticipated that continued genetic investigation will result in more precise screening and improved diagnostic and therapeutic options for colon cancer.

Turcot's syndrome and familial adenomatous polyposis associated with brain tumor: review of related literature

We investigated clinical manifestations in 124 patients with a possible Turcot's syndrome whose data were taken from documented cases. The cases were subclassified mainly on the bases of the type of familial occurrence and listed in five Tables. We searched for differences in colonic manifestation, histologic type of glioma, mode of inheritance, frequency of parental consanguinity, skin lesions and other accompanying lesions among these five groups. The differences of these clinical findings suggested that glioma-polyposis syndrome should be classified as follows; (1) cases of Turcot's syndrome who had characteristic colonic and brain manifestations, (2) cases of FAP associated with glioma, (3) suspicious cases of glioma-polyposis, and (4) cases other than glioma-polyposis syndrome.

Genetic evidence that Turcot syndrome is not allelic to familial adenomatous polyposis

Turcot syndrome (TS) is a rare genetic disease in which brain tumors occur in association with colonic polyposis. Since Turcot's original description in 1959, there have been disagreements about the mode of inheritance as well as the clinical expression of this condition. Some investigators maintain that TS is a phenotypic variant of the autosomal dominant familial adenomatous polyposis (FAP), while others observe that there are clinical differences between TS and FAP, and that the pattern of inheritance of TS is autosomal recessive. The distribution of persons with colonic lesions in a family with a patient of colonic polyposis and a brain tumor, described in this report, favored the recessive hypothesis. In this family, the involvement of the FAP gene on chromosome 5q21-q22 could be excluded by a linkage study using a panel of FAP-linked DNA markers. This finding, which indicates the occurrence of another polyposis gene elsewhere in the genome, will have consequences for the presymptomatic diagnosis of FAP by linked DNA markers. We conclude that TS is a distinct clinical-genetical entity with the triad of atypical polyposis coli, CNS tumors, and a recessive mode of inheritance.

Turcot's syndrome

A non-familial case of cerebellar medulloblastoma associated with adenomatous polyposis coli is described and the literature is reviewed. This is the second reported case of Turcot's syndrome in Australia. A greater understanding of the genetic implications of this rare condition might be achieved through reporting of cases and long-term documentation with polyposis registries.

Rhabdomyosarcoma associated with familial adenomatous polyposis

We report a case of a 16 year old girl with orbital rhabdomyosarcoma who during chemotherapy developed bloody diarrhoea. On investigation she was found to have multiple colonic polyps. Cytogenetic analysis has shown a pattern typical of familial adenomatous polyposis. We present a review of the literature concerning the associations of familial adenomatous polyposis. The association of familial adenomatous polyposis with rhabdomyosarcoma has not been previously reported.

Ocular findings in Turcot syndrome (glioma-polyposis)

Turcot syndrome is a hereditary condition characterized by multiple, adenomatous gastrointestinal polyps associated with neuroepithelial tumors of the central nervous system. The authors examined a patient with Turcot syndrome who had multiple regions of congenital hypertrophy of the retinal pigment epithelium (CHRPE) with areas of surrounding hypopigmentation in the fundi of both eyes. Multiple, bilateral patches of CHRPE have been reported in patients with familial adenomatous polyposis and Gardner syndrome. This finding is thought to be a sensitive and specific clinical marker for these conditions and useful for predicting the presence and development of colorectal polyposis. Our findings provide further evidence that familial adenomatous polyposis, Gardner syndrome, and Turcot syndrome may be related conditions representing the variable phenotypic expression of a single, autosomal dominant genetic disorder. Children and young adults with multiple patches of CHRPE and a family history of adenomatous polyposis may be at increased risk for the development of central nervous system tumors as well as gastrointestinal polyps.

Predictive value of congenital hypertrophy of the retinal pigment epithelium as a clinical marker for familial adenomatous polyposis

One hundred forty-eight members of 53 kindreds with familial adenomatous polyposis (FAP) were examined for congenital hypertrophy of the retinal pigment epithelium (CHRPE) and extracolonic manifestations (ECM) to assess the value of CHRPE as a predictive marker for FAP. Based on eye examination results, the families were divided into 2 groups. In a first group of 34 families, all 61 members diagnosed as having polyps and 13 of the 33 patients at risk had 4 or more lesions distributed in both eyes. By contrast, in a second group of 18 families, all 32 polyposis patients and all 18 members at risk had less than 4 lesions. Extra-colonic manifestations were present in 26 of 34 families in the first group and in 11 of 18 families in the second group. Data on one family with ambiguous ancestry were reviewed separately. The existence of 4 or more CHRPE lesions distributed in both eyes seems to be a congenital marker for FAP, present in 65.4 percent of families. When present in a family: 1) it is found in all diagnosed patients in that family, 2) can therefore be considered predictive for the development of polyps in other family members who carry the trait, and 3) if confirmed by longer follow-up, may possibly preclude members without the trait from further evaluation and surveillance.