The Objective Identification of Dermatoscopic Features using

Spectrophotometric Intracutaneous Analysis

Marc Moncrieff 1,4, Symon Cotton2, Ela Claridge3, Per Hall1

1 - 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

CollagenBlood

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 ResultsFeature Sens (%) Spec (%)

Melanin Globules 100 8.4

Dermal Melanin 96.1 56.8

No Biaxial Symmetry 96.2 29.7

Dermal Melanin Globules 88.5 66.6

Collagen Holes 78.8 74.0

Asymmetry 76.9 62.2

Erythematous Blush 75.0 65.5

Blood Displacement 75 70.3

Biaxial Symmetry 3.8 70.3

Displacement with Blush 63.5 84.8

Early Trial ResultsFeatures Sensitivity (%) Specificity (%)

Collagen Holes + dermal Melanin 76.9 78.0

Dermal Melanin + Displacement with Blush 96.1 56.8

Dermal Melanin + Displacement with blush +

Diameter > 6mm 88.5 72.0

Dermal Melanin + Displacement with blush +

NOT Sym -2 92.3 65.9

Dermal Melanin + Displacement with blush +

Collagen Holes 84.6 73

ROC for Combinations of Features

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

100-Specificity (%)

Sen

sitiv

ity (%

)

Clinical: 7-point Checklist

Dermatoscopy (Binder et al. JAAD,1997)

Dermal Melanin & Displacement/Blush

Dermal Melanin & Displacement/Blush & Diam >6mm

Dermal Melanin & Displacement/Blush & No BiaxialSymmetry

Dermal Melanin & Collagen Holes

ROC for Combinations of Features

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

100-Specificity (%)

Sen

sitiv

ity (%

) Dermatoscopy (Binder et al.JAAD,1997)

Dermal Melanin &Displacement/Blush & NoBiaxial Symmetry

Dermal Melanin & CollagenHoles

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. 1159-62

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 (white) Veil

Blue-Grey Veil

x

=Blue-Grey Veil

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