Attenuated Familial Adenomatous Polyposis: A Phenotypic Diagnosis but Obsolete Term?

Surgical Decision-Making in Familial Adenomatous Polyposis

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder affecting patients with germline mutations of the adenomatous polyposis coli (APC) tumor suppressor gene. The surgical treatment of colorectal disease in FAP, which has the goal of colorectal cancer prevention, varies based on both patient and disease factors but can include the following: total colectomy with ileorectal anastomosis, proctocolectomy with stapled or hand-sewn ileal pouch-anal anastomosis, or total proctocolectomy with end ileostomy. The operative options and extent of resection, as well as the use of endoscopy and chemoprevention for the management of polyposis, will be discussed in detail in this article. In addition, commonly debated management decisions related to the treatment of patients with FAP, including the timing of prophylactic colorectal resections for patients with FAP and management of the polyp burden in the rectum, will be discussed. Finally, genotype considerations and the impact of desmoid disease on operative decisions in the setting of FAP will also be reviewed.

Cribriform-morular Thyroid Carcinoma Arising in a Medulloblastoma Survivor: Two Metachronous Tumors Shared with the Activation of the Wnt Signaling Pathway

Wnt signaling pathway activation is involved in the pathogenesis of a series of malignant tumors and is characterized by the nuclear accumulation of β-catenin protein. The occurrence of two or more Wnt pathway-associated tumors in a single individual is uncommon and generally attributed to inherited cancer syndrome, especially familial adenomatous polyposis (FAP). Herein, we presented a rare case of a child who suffered from the occurrence of Wnt-activated medulloblastoma and cribriform-morular thyroid carcinoma (CMTC) within a 9-year interval. She had no history of FAP and harbored an unexpected somatic mutation of the APC gene in the CMTC tumor. The potential agents involved in the pathogenesis of the two molecular-linked tumors other than FAP were discussed in this report.

Diffuse familial adenomatous intestinal polyposis in childhood: current state of the problem and case report

OBJECTIVE

Aim: To explore the prevalence, clinical characteristics, and diagnostic aspects of diffuse familial adenomatous polyposis in childhood. This objective is accomplished through an extensive review of recent literature, and the presentation of case report from our clinical practice.

PATIENTS AND METHODS

Materials and Methods: We analyzed 75 scientific papers, the findings of which have been documented in the PubMed database. Our search criteria included keywords such as ≪diffuse familial adenomatous intestinal polyposis,≫ ≪children,≫ and ≪diagnosis.≫ Then we conducted a second-stage analysis that involved a detailed review of a practical case - the medical records of inpatient Kh.V. who had been diagnosed with familial adenomatous polyposis.

CONCLUSION

Conclusions: The analysis of the literature data is consistent with the findings from our clinical observations of familial adenomatous polyposis in a patient with complicated family anamnesis. It is worth noting that clinical features do not significantly differ across various types of polyposis. In cases of suspected familial adenomatous polyposis in adolescents, genetic testing is crucial.

Low adenoma burden in unselected patients with a pathogenic APC variant

PURPOSE

Genomic screening can improve clinical outcomes, but presentation of individuals with risk for polyposis identified via genomic screening is unknown. To inform assessment of clinical utility of genomic screening for polyposis risk, clinical presentation of individuals in an unselected health care system cohort with an APC pathogenic or likely pathogenic (P/LP) variant causative of familial adenomatous polyposis are described.

METHODS

Electronic health records of individuals with an APC P/LP variant identified via the MyCode program (MyCode APC+) were reviewed to assess adenoma burden and compare it among individuals with a clinical diagnosis of familial adenomatous polyposis and matched variant-negative controls.

RESULTS

The prevalence of APC P/LP variants in this health care cohort is estimated to be 1 in 2800. Twenty-four MyCode APC+ individuals were identified during the study period. Median age at result disclosure was 53 years. Rate of clinical polyposis was 8%. Two of six participants with a classic region variant and none of those with an attenuated region variant had polyposis. MyCode APC+ participants did not differ from controls in cumulative adenoma count.

CONCLUSION

APC P/LP variant prevalence estimate in the MyCode cohort is higher than prior published prevalence rates. Individuals with APC P/LP variants identified via genomic screening had a low adenoma burden.

Update on Surgical Management of FAP

Familial adenomatous polyposis (FAP) is an autosomal dominant disease caused by pathogenic germline adenomatous polyposis coli mutation, and characterized with multiple adenomas in the colon and the rectum. Various genetic variants have been confirmed to be associated with corresponding FAP phenotypes, which play important roles in the diagnosis and surgical treatment of FAP. Generally, proctocolectomy is recommended for FAP patients at the age of 20s. Exceptionally, for patients with attenuated FAP, high-risk of desmoid, chemoprevention therapy, or other circumstances, surgery can be postponed. With the wide application of minimal invasive surgery in colorectal cancer, laparoscopic, robotic surgery, and natural orifice specimen extraction are proved to be feasible for FAP patients, but high-level evidences are needed to confirm their safety and advantages. In the times of precise medicine, the surgical management of FAP should vary with individuals based on genotype, phenotype, and clinical practice. Therefore, in addition to innovation in surgical procedures, investigation in links between genetic features and phenotypes will be helpful to optimize the surgical management of FAP in the future.

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.