Sheffield 2026 Presented e-posters Thursday

To describe patterns of subclinical periocular tumour spread along planes of least resistance, with emphasis on peri-canalicular and lamellar extension, and highlighting the implications for surgical planning and margin control.

A retrospective case series of four periocular malignancies with unique invasion patterns. Clinical, surgical, and histopathologic findings were reviewed. Observations were contextualised with a focused literature review on low‑resistance pathways and their role in periocular tumour propagation.

Four patients (three basal cell carcinomas and one squamous cell carcinoma) demonstrated tumour spread along microanatomical paths of least resistance. The three cases of basal cell carcinoma were all high‑risk types and showed medial extension along peri-canalicular connective tissue, with two cases requiring canalicular sacrifice and iterative excisions to achieve tumour clearance. The case of squamous cell carcinoma infiltrated extensively between the orbicularis muscle and tarsal plate plane, with a ‘T’ shaped invasion pattern on histology.

Periocular malignancies can exploit low-resistance pathways, including peri-canalicular connective tissue and lamellar interfaces, allowing extension beyond clinically apparent boundaries. Recognising these routes is critical for accurate margin assessment and effective surgical planning. Histopathologists must be vigilant for peri-canalicular spread and ensure that margins containing canalicular tissue have sections cut through them in their entirety, to determine the need for further excision. This process relies on close collaboration between the histopathologist and oculoplastic surgeon, which may include joint review of histological findings.