The Objective Identification of Dermatoscopic Features using Spectrophotometric Intracutaneous Analysis

Marc Moncrieff 1,4, Symon Cotton 2, Ela Claridge 3, Per Hall Department of Plastic & Reconstructive Surgery, Addenbrooke’s Hospital, Cambridge, UK 2 - Astron Clinica, Cambridge, UK 3- Department of Computer Science, University of Birmingham, UK 4 - Department of Plastic & Reconstructive Surgery, West Norwich Hospital, Norwich, UK

SIA Technique developed in UK Analyses remitted light from the skin Produces ‘SIAgraphs’

Epidermal melanin Collagen Blood Dermal melanin Array spectrometerLight SIA

Total Melanin SIAgraph

Tumour punches holes in collagen Collagen thrown into whorls and rosettes around invasive nodule Thickening of collagen at invasive margin Collagen SIAgraph

Blood displaced by invasive tumour Erythematous blush at invading margin Blood SIAgraph

Dermal Melanin SIAgraph

Early Trial Results FeatureSens (%) Spec (%) Melanin Globules Dermal Melanin No Biaxial Symmetry Dermal Melanin Globules Collagen Holes Asymmetry Erythematous Blush Blood Displacement Biaxial Symmetry Displacement with Blush

Early Trial Results

Very simple features identified As accurate as dermatoscopy Results do not include interpretation of dermatoscopic features

Skin Surface Microscopy / Dermatoscopy A (useful) adjunct to clinical diagnosis Limitations –training very limited and very necessary –subjective findings –subjective interpretation

Blue Formed by: –Dermal melanin –dermal Hb –thinning of collagen –thickening of keratin Hidden by: – epidermal melanin – thrombosis

Bahmer et al (1990): “Histopathologically this corresponds to superficial fibrosis with melanophages and / or pigmented malignant cells in the papillary dermis” Bahmer et al (1990) J Am Acad Dermatol 23: pp Blue - Grey (white) Veil

Menzies et al (1996): “It is the single most significant surface microscopic finding of invasive melanoma” Menzies et al (1996) An Atlas of Surface Microscopy of Pigmented Skin Lesions (p.18) Blue - Grey (white) Veil

Blue-Grey Veil x

=

Histology

Summary Blue/grey veil detected by SIAscopy Sensitivity = 96% for invasive melanoma Allows objective assessment of surface microscopic features according to underlying histopathology The SIAscope is a diagnostic tool in its own right