From Gardner fibroma diagnosis to constitutional APC mutation detection: a one-way street

Nonmalignant Features Associated with Inherited Colorectal Cancer Syndromes-Clues for Diagnosis

Simple Summary

Familiarity with nonmalignant features and comorbidities of cancer predisposition syndromes may raise awareness and assist clinicians in the diagnosis and interpretation of molecular test results. Genetic predisposition to colorectal cancer (CRC) should be suspected mainly in young patients, in patients with significant family histories, multiple polyps, mismatch repair-deficient tumors, and in association with malignant or nonmalignant comorbidities. The aim of this review is to describe the main nonmalignant comorbidities associated with selected CRC predisposition syndromes that may serve as valuable diagnostic clues for clinicians and genetic professionals.

Abstract

Genetic diagnosis of affected individuals and predictive testing of their at-risk relatives, combined with intensive cancer surveillance, has an enormous cancer-preventive potential in these families. A lack of awareness may be part of the reason why the underlying germline cause remains unexplained in a large proportion of patients with CRC. Various extracolonic features, mainly dermatologic, ophthalmic, dental, endocrine, vascular, and reproductive manifestations occur in many of the cancer predisposition syndromes associated with CRC and polyposis. Some are mediated via the WNT, TGF-β, or mTOR pathways. However the pathogenesis of most features is still obscure. Here we review the extracolonic features of the main syndromes, the existing information regarding their prevalence, and the pathways involved in their pathogenesis. This knowledge could be useful for care managers from different professional disciplines, and used to raise awareness, enable diagnosis, and assist in the process of genetic testing and interpretation.

[Familial adenomatous polyposis, desmoid tumors and Gardner syndrome]

About 15 % of patients with familial adenomatous polyposis "PAF" develop one or more desmoid tumors in their lifetime. These are benign mesenchymal tumors with local aggressivity but with no potential for metastases. Most of the desmoids tumors result from a sporadic genetic anomaly in the β catenin gene. When related to familial adenomatous polyposis or "PAF", this mutation is not present, and the patients must be sent in genetic counselling. The PAF is a dominant autosomic illness related to a germinal mutation in the APC gene. Sometimes, these tumors can be the first manifestation of the illness. The diagnosis in a context of PAF can be easily done by imaging, but a pathological confirmation is needed. These tumors raise a therapeutic problem because of their heterogeneity and the absence of predictive biomarkers along illness evolution. The identification of prognostic biological and clinical factors would make easier the selection of patients requiring first-line treatment, as spontaneous remissions have also been observed in patients with FAP whom which an active surveillance could also be a valid therapeutic option. The particularity of desmoids tumors associated to PAF lies in their predominantly intra-abdominal location and the risk of complication. In the last ten years, surgery has largely given way to conservative treatments such as chemotherapy and more recently to tyrosine kinase inhibitors that have shown their efficacy with a significant improvement in progression-free survival of patients.

From Gardner fibroma diagnosis to constitutional APC mutation detection: a one-way street

We report a young child without a family history of FAP, who promptly underwent APC testing after the histological confirmation of a paraspinal GAF that was not isolated. Our case report reinforces the suggestion advanced by previous authors for an APC analysis in all patients with GAF.