The 'other' colonic polyposis syndromes-evolving insights and guidance for endoscopists

Polyposis syndromes contribute to a significant proportion of colorectal cancer (CRC) diagnoses. While Lynch syndrome (LS) and familial adenomatous polyposis (FAP) are well characterised, a growing number of rarer polyposis syndromes are increasingly recognised in clinical practice. These conditions often present with overlapping phenotypes and variable penetrance, posing diagnostic and management challenges for the practising clinician. The evidence base remains limited, with current guidance largely derived from small cohort studies and expert opinion. This narrative review summarises the current literature on the genetic basis, clinical manifestations, and endoscopic features of the rarer colorectal polyposis syndromes, excluding LS and FAP.

A comprehensive literature search was conducted using PubMed and Ovid databases. Selected articles were evaluated for relevance and quality, and key findings were synthesised narratively to provide an overview of current knowledge and emerging trends relating to the rarer polyposis syndromes.

This review consolidates international recommendations for surveillance and management, with a focus on practical guidance for the endoscopist. Advances in next-generation sequencing and multigene panel testing have reshaped our understanding of polyposis genetics, leading to the identification of several novel autosomal dominant and recessive syndromes. Despite these discoveries, surveillance protocols remain heterogeneous, and gaps persist in defining cancer risk, optimal timing of intervention, and the role of chemoprevention. Greater awareness of these syndromes among clinicians is essential for timely diagnosis and personalised management.

Collaborative registries, prospective data, and consensus-driven guidelines are urgently required to standardise care and improve outcomes for patients with rare polyposis syndromes.