Periocular malignancy and eyelid reconstruction

Abstract

Non-melanoma skin cancer is the most common cancer in Australia. Basal cell carcinoma and squamous cell carcinoma are the two most frequently encountered types of non-melanoma skin cancer, and together they make up over 90% of all skin cancers. The periocular region is involved in 10% of cases and is associated with significantly more disease-related morbidity due to the local effect of both the disease and the surgical treatment on ocular adnexa. Therefore, it is imperative that high-risk tumours are correctly identified to ensure appropriate management and surveillance. Surgical excision remains the gold standard treatment but functional reconstruction of the eyelid represents an ongoing challenge. Despite the wide range of autologous and artificial eyelid substitutes, there is yet to be an ideal replacement for the specialised eyelid tissue called the tarsus. The tarsus is responsible for both structural support and physical form, making its adequate substitution fundamental to functional outcomes. Numerable uncertainties remain regarding the staging and management of periocular non-melanoma skin cancer which, combined with our lack of ideal eyelid tarsus substitutes, represents the basis for work undertaken as part of this thesis. Previous studies contributing to our knowledge of periocular basal cell carcinoma histological subtypes and treatment of invasive disease are first reviewed in Chapter 2. Chapter 3 subsequently summarises our understanding of periocular squamous cell carcinoma with a particular focus on the utilisation and prognostic role of the most up-to-date American Joint Committee on Cancer (AJCC) staging system for the eyelid carcinoma. In order to determine the required properties for the ideal tarsus tissue substitute, Chapter 4 analyses the normal biomechanical properties of the eyelid tarsus tissue. This study, the first of its kind for human tarsus tissue, provides a benchmark for bioengineering studies described in the following chapter. In Chapter 5, we describe the development of a novel bioengineered three-dimensional scaffold which is tailor-made to behave biomechanically like natural tarsus. In order to improve in vivo compatibility, we also successfully cultured fibroblasts from eyelid skin samples which were then seeded onto our bioengineered scaffolds, the results of which are described in Chapter 6. Finally, insights into the presentation, staging and management of periocular basal cell carcinoma and squamous cell carcinoma, along with our novel bioengineered eyelid tarsus substitute are placed in the context of the previous literature in Chapter 7, before possible directions for future studies are discussed in Chapter 8.