Histopathological characteristics of metastasizing squamous cell carcinoma of the skin and lips

AIMS The reported incidence of metastasis from squamous cell carcinoma (SCC) of the skin and lip varies between 0.5% and 16%. Clinical and histopathological criteria have been proposed to identify tumours that may have an increased risk of metastasis. The aim of this study was to define such high-risk tumours, especially since the incidence of SCC of the skin is increasing. METHODS AND RESULTS Histopathological features of metastasized skin and lip tumours and a matched group of non-metastasizing tumours were reassessed. Characteristics studied were: tumour width, excision margins, histological subtype, Clark level, Breslow depth, tumour differentiation, inflammation, perineural and angio-invasive growth, ulceration and desmoplasia. Data were statistically analysed separately for skin and labial lesions. Desmoplasia, Clark level, Breslow depth, maximum diameter, angio-invasion, grading, perineural invasion, plasma cells and eosinophilic inflammatory response proved to be statistically significantly related to metastasis of skin tumours. Breslow depth, plasma cells and grading appeared to be statistically significantly related to metastasis of SCC of the lips. CONCLUSIONS A typical metastatic SCC showed: a tumour width of at least 15 mm, a vertical tumour thickness (=Breslow) of at least 2 mm, less differentiation, presence of desmoplasia and an inflammatory response with eosinophils and plasma cells.