Identification of a rare MET variant in a familial case of extramammary Paget's disease.

Extramammary Paget's disease (EMPD) is an intraepithelial adenocarcinoma that primarily affects the genital and axillary areas in elderly individuals. A limited number of paired familial EMPD cases (i.e., parent-offspring, siblings) have been reported, whereas the genetics of these cases have not yet been adequately studied. We report the first familial case of EMPD involving three affected siblings. The tumour-only multi-gene panel testing using surgical specimens revealed a heterozygous c.2997A>C (p.Glu999Asp) nonsynonymous variant in the proto-oncogene MET (NM_000245.4) in the three affected siblings. The germline multi-gene panel testing using peripheral blood lymphocytes revealed the same missense MET variant in all five family members, including the two asymptomatic offspring (51 and 37 years of age). The MET variant we identified could be involved in EMPD carcinogenesis. Further genomic analyses of familial cases of EMPD are warranted to validate the pathogenic relevance of MET variants in EMPD development.

Genotype-phenotype correlation of small-intestinal polyps on small-bowel capsule endoscopy in familial adenomatous polyposis.

BACKGROUND AND AIMS: In familial adenomatous polyposis (FAP), neoplastic lesions outside the colon have become increasingly important. The genotype-phenotype correlation has been established for duodenal polyps, and regular screening is recommended. However, this correlation remains unclear for small-intestinal lesions, except for reports on the relationship between their occurrence and Spigelman stage. Here, we used small-bowel capsule endoscopy (SBCE) to investigate the genotype-phenotype correlation of small-intestinal polyps in FAP. METHODS: The genotype-phenotype correlation of small-intestinal polyps was investigated in patients with FAP who underwent SBCE, Esophagogastroduodenoscopy (EGD), and adenomatous polyposis coli (APC) gene analysis. Of 64 patients with FAP who underwent SBCE, 41 were included in the final analysis, 4 did not undergo a complete small intestine examination, and 19 did not undergo genetic analysis. RESULTS: The prevalence (median number) of small-intestinal polyps by Spigelman stage was 26% (1.5), 0% (0), 44% (5), 60% (4), and 73% (25.5) for stages 0 to IV, respectively. Significantly more small-intestinal polyps were found in Spigelman stage III and IV groups than in the stage 0 group (P < .05). The APC variant was negative for 6 patients (15%), and the sites associated with more than 5 small-intestinal polyps were codons 278, 1062, 1114, 1281, 1307, 1314, and 1504. CONCLUSIONS: In FAP patients, SBCE surveillance is potentially recommended for patients with pathogenic variants in the APC gene at codons 278 and 1062 to 1504 or with Spigelman stage III or higher.

Germline variants in cancer-predisposing genes in pancreatic cancer patients with a family history of cancer.

BACKGROUND: Our phase II trial (FABRIC study) failed to verify the efficacy of gemcitabine plus oxaliplatin (GEMOX) in patients with pancreatic ductal adenocarcinoma (PDAC) with a familial or personal history of pancreatic, breast, ovarian or prostate cancer, which suggested that a family and personal history may be insufficient to determine response to platinum-based chemotherapy. METHODS: This ancillary analysis aimed to investigate the prevalence of germline variants of homologous recombination repair (HRR)-related genes and clarify the association of germline variants with the efficacy of GEMOX and patient outcome in PDAC patients. Of 45 patients enrolled in FABRIC study, 27 patients were registered in this ancillary analysis. RESULTS: Of the identified variants in HRR-related genes, one variant was considered pathogenic and eight variants in six patients (22%) were variants of unknown significance (VUS). Objective response to GEMOX was achieved by 43% of the seven patients and tended to be higher than that of patients without such variants (25%). Pathogenic/VUS variant in HRR-related genes was an independent favorable factor for progression-free survival (hazard ratio, 0.322; P = 0.047) and overall survival (hazard ratio, 0.195; P = 0.023) in multivariable analysis. CONCLUSIONS: The prevalence of germline variants in PDAC patients was very low even among patients with a familial/personal history of pancreatic, breast, ovarian or prostate cancer. Patients with one or more germline variants in HRR-related genes classified as pathogenic or VUS may have the potential to obtain better response to GEMOX and have better outcomes.

Malignant brain tumor in an infant showing histopathological features of yolk sac tumor but genetic and epigenetic features of AT/RT.

SMARCA4 pathogenic variants are rarely detected in pediatric brain tumors other than atypical teratoid rhabdoid tumors (AT/RTs) without INI1 deficiency or in some cases of medulloblastoma. Here, we report an atypical intracranial immature teratoma that recurred as a yolk sac tumor with metastatic spinal and lung lesions. Sequencing of the tumor revealed two SMARCA4 variants, including a splice-site variant and a non-synonymous variant of uncertain significance. Additionally, the methylation signature of the tumor was close to that of AT/RTs. Our case might be a yet-unrecognized subtype of pediatric tumors in which inactivation of SMARCA4 contributes to the pathogenesis.

Gastric cancer is highly prevalent in Lynch syndrome patients with atrophic gastritis.

BACKGROUND: Although gastric cancer is one of the Lynch syndrome (LS)-related tumors, the clinicopathological features of gastric cancer in patients with LS remain uncertain. To investigate the incidence risk and clinicopathological features of gastric neoplasms in LS, we conducted a retrospective cohort study in Japanese LS patients. METHODS: LS patients with pathogenic mismatch repair (MMR) gene variants were extracted from the LS registry of the National Cancer Center Hospital, Japan. Cumulative risks of gastric neoplasm, including dysplasia and cancer, were estimated using the Kaplan-Meier method. Gastric atrophy was evaluated endoscopically and/or histologically. Immunohistochemical staining for MMR proteins was performed for all available specimens. RESULTS: Of 118 eligible patients, 26 patients were diagnosed with 58 gastric neoplasms. The cumulative incidence of gastric neoplasm was 41.0% (95% confidence interval, 26.9-55.0) at the age of 70. Of these, 13 (50%) patients developed synchronous and/or metachronous multiple gastric neoplasms. Among the 49 gastric neoplasms available for detailed pathological evaluation, all were associated with intestinal metaplasia. Immunohistochemically, 42 (86%) were MMR-deficient. The individuals with gastric atrophy had a significantly higher risk of developing gastric neoplasms compared with those without gastric atrophy (26 cases/54 individuals vs. 0 cases/53 individuals) (P = 0.026). CONCLUSION: LS patients, particularly those with atrophic gastritis, are at high risk of gastric neoplasm and often develop multiple tumors. Endoscopic surveillance for gastric cancer is recommended for LS patients, especially those with atrophic gastritis.

Myxofibrosarcoma harboring an MLH1 pathogenic germline variant associated with Muir-Torre syndrome: a case report.

BACKGROUND: Muir-Torre syndrome (MTS), which accounts for a small subset (1-3 %) of Lynch syndrome (LS), is an autosomal dominant genetic disorder characterized by sebaceous gland or keratoacanthoma associated with visceral malignancies. Most families with MTS have pathogenic germline variants (PGV) in MSH2. Sarcomas are not common on the LS tumor spectrum, and sarcomas associated with MTS are extremely rare. CASE PRESENTATION: Here we report a myxofibrosarcoma of the abdominal wall in a 73-year-old man with a sebaceoma that occurred synchronically, leading to a diagnosis of MTS. The loss of MLH1 and PMS2 protein expression was detected in immunohistochemistry, and high-frequency microsatellite instability (MSI-H) was also confirmed. A germline genetic analysis revealed that he harbored the MLH1 PGV. CONCLUSIONS: This is the first case of MSI-H myxofibrosarcoma with MTS in an MLH1 PGV carrier. Although rare, we should recognize that sarcomas can be part of the spectrum of LS and MTS.

Simple prediction model for homologous recombination deficiency in breast cancers in adolescents and young adults.

PURPOSE: Homologous recombination deficiency (HRD), which influences the efficacy of PARP inhibitor- and platinum agent-based therapies, is a prevalent phenotype of breast cancer in adolescents and young adults (AYAs; 15-39 years old). However, HRD score, indicating HRD status, is not routinely assessed in the breast oncology clinic, particularly in patients without germline BRCA1/2 mutations. Hence, we sought to develop a model for determining HRD status based on genetic and clinicopathological factors. METHODS: Subjects were our own cohort of 46 Japanese AYA breast cancer patients and two existing breast cancer cohorts of US and European patients. Models for prediction of the HRD-high phenotype, defined as HRD score ≥ 42, were constructed by logistic regression analysis, using as explanatory variables genetic and clinicopathological factors assessable in the clinical setting. RESULTS: In all three cohorts, the HRD-high phenotype was associated with germline BRCA1/2 mutation, somatic TP53 mutation, triple-negative subtype, and higher tumor grade. A model based on these four factors, developed using the US cohort, was validated in the Japanese and European AYA cases: area under the receiver operating characteristic curve [AUC] was 0.90 and 0.96, respectively. A model based on three factors excluding germline BRCA1/2 mutation also yielded high-predictive power in cases from these two cohorts without germline BRCA1/2 mutations: AUC was 0.92 and 0.90, respectively. CONCLUSIONS: The HRD-high phenotype of AYA breast cancer patients can be deduced from genomic and pathological factors that are routinely examined in the oncology clinic, irrespective of germline BRCA1/2 mutations.

Cytoplasmic MSH2 immunoreactivity in a patient with Lynch syndrome with an EPCAM-MSH2 fusion.

AIMS: Immunohistochemistry for mismatch repair (MMR) proteins is being increasingly used to examine MMR status in tumours. The aim of the present article was to report the case of a colon cancer patient with Lynch syndrome who showed unusual cytoplasmic MMR protein localization. METHODS AND RESULTS: Histologically, the colon cancer was diagnosed as medullary carcinoma associated with prominent tumour-infiltrating lymphocytes and a Crohn's-like reaction. Immunohistochemistry revealed cytoplasmic and nuclear expression of MSH2 in non-neoplastic cells, and exclusively cytoplasmic expression in tumour cells. MSH6 expression was nuclear in non-neoplastic cells, but was lost in tumour cells. Nuclear expression of MLH1 and PMS2 was retained in both non-neoplastic and tumour cells. The tumour was microsatellite instability-high, which is indicative of defective MMR function. A subsequent germline mutation analysis identified a genomic deletion spanning the 3' region of EPCAM and the 5' region of MSH2, resulting in an in-frame fusion of EPCAM and MSH2. CONCLUSIONS: The unusual cytoplasmic immunoreactivity of MSH2 was considered to be attributable to the non-functional EPCAM-MSH2 fusion product. The present case illustrates that not only loss of expression, but also abnormal localization, of MMR proteins is indicative of a defective MMR system.

Cardiac paraganglioma with a novel germline mutation of succinate dehydrogenase gene D.

A 58-year-old woman with a past medical history of a carotid body tumor, resected 4 months prior to presentation, was admitted to our hospital for treatment of a cardiac tumor that was identified on post-operative echocardiography and chest computed tomography. The cardiac tumor was surgically removed and identified pathologically as a paraganglioma, similarly to the carotid body tumor. Genetic analysis of both tumors identified a non-synonymous mutation in the succinate dehydrogenase (SDH) gene D, Exon4, c.320T>C, p.Leu107Pro showing co-segregation with paternal transmission and maternal imprinting among family members. This novel mutation appears to be the cause of familial paraganglioma in this patient.

Germline PMS2 mutation screened by mismatch repair protein immunohistochemistry of colorectal cancer in Japan.

Germline PMS2 gene mutations were detected by RT-PCR/direct sequencing of total RNA extracted from puromycin-treated peripheral blood lymphocytes (PBL) and multiplex ligation-dependent probe amplification (MLPA) analyses of Japanese patients with colorectal cancer (CRC) fulfilling either the revised Bethesda Guidelines or being an age at disease onset of younger than 70 years, and screened by mismatch repair protein immunohistochemistry of formalin-fixed paraffin embedded sections. Of the 501 subjects examined, 7 (1.40%) showed the downregulated expression of the PMS2 protein alone and were referred to the genetic counseling clinic. Germline PMS2 mutations were detected in 6 (85.7%), including 3 nonsense and 1 frameshift mutations by RT-PCR/direct sequencing and 2 genomic deletions by MLPA. No mutations were identified in the other MMR genes (i.e. MSH2, MLH1 and MSH6). The prevalence of the downregulated expression of the PMS2 protein alone was 1.40% among the subjects examined and IHC results predicted the presence of PMS2 germline mutations. RT-PCR from puromycin-treated PBL and MLPA may be employed as the first screening step to detect PMS2 mutations without pseudogene interference, followed by the long-range PCR/nested PCR validation using genomic DNA.

Depressed-type submucosal invasive colorectal cancer in a patient with Lynch syndrome diagnosed using short-interval colonoscopy.

Although regular colonoscopy surveillance is recommended for patients with Lynch syndrome (LS) who underwent partial colectomy, the appropriate interval has not been determined. We report a case of colorectal cancer (CRC) detected by short-interval surveillance colonoscopy (SC) in a patient with LS having a past history of partial colectomy. A 65-year-old man underwent sigmoidectomy for advanced CRC. His family history revealed that his two younger brothers had CRC in their twenties and thirties, respectively, and the patient met with the criteria in the Revised Bethesda Guidelines. After confirming the loss of MSH2 protein expression in the primary tumor, subsequent genetic testing showed germline mutation with a large deletion of exon 7-14 in the MSH2 gene, indicating a diagnosis of LS. After the diagnosis of LS, the patient underwent annual SC. Three years after the initial surgery, superficial submucosal invasive cancer was detected. Subsequently, SC after a 6-month interval revealed a deep submucosal invasive cancer (7 mm in diameter). Although additional surgery was recommended, considering his comorbidities, regular SC rather than colectomy was selected. Even shorter-interval SC carried out within a year is not sufficient to detect endoscopically resectable tumors in some high-risk LS cases.

Familial adenomatous polyposis-associated and sporadic pyloric gland adenomas of the upper gastrointestinal tract share common genetic features.

AIMS: Familial adenomatous polyposis (FAP) is a hereditary cancer predisposition syndrome caused by a germline APC mutation. A recent study showed the enrichment of pyloric gland adenomas (PGAs) of the stomach, in addition to fundic gland polyps (FGPs) and foveolar-type adenomas (FAs), in patients with FAP. In the present study, we analysed the genetic alterations in these FAP-associated gastric lesions. METHODS AND RESULTS: Mutational statuses of GNAS and KRAS, which are frequently mutated in sporadic PGAs, as well as those of APC, were examined in PGAs, FAs and FGPs in patients with FAP using Sanger sequencing. Our analysis identified GNAS mutations in five of six PGAs (83%), but in none of the three FAs or the 40 FGPs examined. KRAS mutations were identified in four PGAs (67%), one FA (33%) and one FGP (3%). Somatic truncating APC mutations were found in all PGAs (100%), two FAs (67%) and 14 FGPs (47%). We additionally analysed sporadic PGAs of the stomach and duodenum and identified truncating APC mutations in 11 of 25 lesions (44%). CONCLUSIONS: FAP-associated and sporadic PGAs not only show similar morphologies, but also share common genetic aberrations, including mutations of GNAS, KRAS and APC.

Familial Adenomatous Polyposis with Atypical Clinical Morphology and Genetic Variants.

Familial adenomatous polyposis (FAP) is caused by pathogenic variants of the APC gene on the long arm of chromosome 5. An analysis showed an association between germline APC gene variants and clinical signs of FAP; however, attenuated FAP has also been reported in cases with pathogenic variants. In contrast, a phenotype of FAP with no APC germline pathogenic variant and with few signs has been reported. We herein report a 16-year-old girl in whom the presence of multiple large bowel cancers from a young age and several small bowel cancers reflected a carcinogenic tendency higher than that typical for FAP.

Assessing the efficacy of target adaptive sampling long-read sequencing through hereditary cancer patient genomes.

Innovations in sequencing technology have led to the discovery of novel mutations that cause inherited diseases. However, many patients with suspected genetic diseases remain undiagnosed. Long-read sequencing technologies are expected to significantly improve the diagnostic rate by overcoming the limitations of short-read sequencing. In addition, Oxford Nanopore Technologies (ONT) offers adaptive sampling and computationally driven target enrichment technology. This enables more affordable intensive analysis of target gene regions compared to standard non-selective long-read sequencing. In this study, we developed an efficient computational workflow for target adaptive sampling long-read sequencing (TAS-LRS) and evaluated it through application to 33 genomes collected from suspected hereditary cancer patients. Our workflow can identify single nucleotide variants with nearly the same accuracy as the short-read platform and elucidate complex forms of structural variations. We also newly identified several SINE-R/VNTR/Alu (SVA) elements affecting the APC gene in two patients with familial adenomatous polyposis, as well as their sites of origin. In addition, we demonstrated that off-target reads from adaptive sampling, which is typically discarded, can be effectively used to accurately genotype common single-nucleotide polymorphisms (SNPs) across the entire genome, enabling the calculation of a polygenic risk score. Furthermore, we identified allele-specific MLH1 promoter hypermethylation in a Lynch syndrome patient. In summary, our workflow with TAS-LRS can simultaneously capture monogenic risk variants including complex structural variations, polygenic background as well as epigenetic alterations, and will be an efficient platform for genetic disease research and diagnosis.

A complex rearrangement between APC and TP63 associated with familial adenomatous polyposis identified by multimodal genomic analysis: a case report.

Genetic testing of the APC gene by sequencing analysis and MLPA is available across commercial laboratories for the definitive genetic diagnosis of familial adenomatous polyposis (FAP). However, some genetic alterations are difficult to detect using conventional analyses. Here, we report a case of a complex genomic APC-TP63 rearrangement, which was identified in a patient with FAP by a series of genomic analyses, including multigene panel testing, chromosomal analyses, and long-read sequencing. A woman in her thirties was diagnosed with FAP due to multiple polyps in her colon and underwent total colectomy. Subsequent examination revealed fundic gland polyposis. No family history suggesting FAP was noted except for a first-degree relative with desmoid fibromatosis. The conventional APC gene testing was performed by her former doctor, but no pathogenic variant was detected, except for 2 variants of unknown significance. The patient was referred to our hospital for further genetic analysis. After obtaining informed consent in genetic counseling, we conducted a multigene panel analysis. As insertion of a part of the TP63 sequence was detected within exon16 of APC, further analyses, including chromosomal analysis and long-read sequencing, were performed and a complex translocation between chromosomes 3 and 5 containing several breakpoints in TP63 and APC was identified. No phenotype associated with TP63 pathogenic variants, such as split-hand/foot malformation (SHFM) or ectrodactyly, ectodermal dysplasia, or cleft lip/palate syndrome (EEC) was identified in the patient or her relatives. Multimodal genomic analyses should be considered in cases where no pathogenic germline variants are detected by conventional genetic testing despite an evident medical or family history of hereditary cancer syndromes.

Endoscopic management of familial adenomatous polyposis targeting colorectal lesions greater than 5 mm in size: a single-center retrospective study.

Preserving the colon while preventing colorectal cancer is challenging in patients with familial adenomatous polyposis. Although prophylactic colectomy is the current standard of care, some patients with familial adenomatous polyposis may wish to postpone colectomy as long as polyposis can be managed by endoscopic resection. This study examined our endoscopic management and prognostic results for patients with familial adenomatous polyposis who refused to undergo colectomy. We retrospectively analyzed the data of 12 patients with familial adenomatous polyposis treated at our hospital between January 1995 and December 2020. All patients opted to postpone prophylactic colectomy although they had significant polyp burdens and underwent endoscopic management, in which colorectal polyps sized > 5 mm were thoroughly resected during baseline colonoscopies and subsequently, newly arising colorectal polyps sized > 5 mm were periodically resected during surveillance colonoscopies. Patients (median age, 33 years) were followed up for a median of 5.2 years. The median number of colonoscopies and resected lesions per patient was 2 and 14 at baseline as well as, 9 and 32 during surveillance, respectively. The interval between colonoscopies was 1.0 and 7.0 months for baseline and surveillance, respectively. The colons of all 12 patients were preserved, and no invasive colorectal cancer developed. In 10 patients, 35 cases of high-grade dysplasia were observed and managed by endoscopic resection. Repeated endoscopic resection of colorectal polyps sized > 5 mm with appropriate surveillance may be an alternative form of endoscopic management for patients with familial adenomatous polyposis wishing to postpone colectomy.

A novel pathogenic variant of the FH gene in a family with hereditary leiomyomatosis and renal cell carcinoma.

Hereditary leiomyomatosis and renal cell carcinoma caused by loss-of-function germline variants of the FH gene can develop into aggressive renal cell carcinoma (RCC). We report the case of a 27-year-old man who died of RCC. Genetic testing revealed a novel pathogenic variant of FH, NM_000143.3:c.1013_1014del (p.Ile338Serfs*3), that was also identified in healthy siblings. Identification of genetic causes in the proband helped us to provide relatives with precise genetic counseling and appropriate surveillance programs.

Solid-pseudopapillary neoplasm of the pancreas in a patient with familial adenomatous polyposis: a case report.

BACKGROUND: Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of colonic polyps, and extracolonic manifestations are likely to occur. Pancreatic tumors are rare extracolonic manifestations in patients with FAP, among which solid-pseudopapillary neoplasm (SPN) are extremely rare. We report here a patient with an SPN of the pancreas found during the follow-up of FAP. CASE PRESENTATION: A 20-year-old woman was diagnosed with FAP 3 years previously by colonoscopy which revealed less than 100 colonic polyps within the entire colon. She complained of left upper abdominal pain and a 10-cm solid and cystic pancreatic tumor was found by computed tomography scan. Solid and cystic components within the tumor were seen on abdominal magnetic resonance imaging. Simultaneous laparoscopic resection of the distal pancreas and subtotal colectomy was performed. Histopathological findings confirmed the pancreatic tumor as an SPN without malignancy. Abnormal staining of beta-catenin was observed by immunohistochemical study. Multiple polyps in the colorectum were not malignant. Molecular biological analysis from peripheral blood samples revealed a decrease in the copy number of the promoter 1A and 1B region of the APC gene, which resulted in decreased expression of the APC gene. CONCLUSIONS: A rare association of SPN with FAP is reported. The genetic background with relation to beta-catenin abnormalities is interesting to consider tumor development. So far, there are few reports of SPN in a patient with FAP. Both lesions were treated simultaneously by laparoscopic resection.

Germline multigene panel testing revealed a BRCA2 pathogenic variant in a patient with suspected Lynch syndrome.

There has been a rapid advance in germline multigene panel testing by next-generation sequencing, and it is being widely used in clinical settings. A 56-year-old woman suspected of having Lynch syndrome was identified as a BRCA2 pathogenic variant carrier by multigene panel testing. The patient was diagnosed with endometrial cancer at the age of 39 years, and total laparoscopic hysterectomy and bilateral salpingectomy were performed at the age of 49 years; however, bilateral oophorectomy was not performed at that time. As she had a family history of colorectal cancer and a history of endometrial cancer, Lynch syndrome was suspected. However, germline multigene panel testing revealed a pathogenic BRCA2 variant rather than pathogenic variants in mismatch repair genes. In this case, with conventional genetic risk assessment, we were unable to determine whether the patient had a high risk of hereditary breast and ovarian cancer; thus, germline multigene panel testing may provide valuable information to improve disease management strategies for patients in clinical settings. Particularly, germline multigene panel testing may be useful for detecting hereditary tumor syndromes if a patient does not present with a typical family history of cancer.