Dermoscopy Notes

DERMOSCOPY NOTES

ALGORITHMS

The first step algorithm identifies whether a lesion is melanocytic or nonmelanocytic. Various algorithms may be used to distinguish benign melanocytic lesions from malignant melanoma:

·  ABCD rule

·  Menzies method

·  7-point rule

If these algorithms appear too complicated, use the 3-point checklist to identify malignant pigmented lesions.

I. ABCD rule

The ABCD rule (Stolz method) is used for the dermoscopic differentiation between benign melanocytic lesions and melanoma. The likelihood of melanoma depends on adding up the scores for different features as shown below.

Criteria / Score X / Factor = / Results
Asymmetry
In perpendicular axes: contour, colours and structures / 0 - 2 / 1.3 / 0 - 2.6
Borders
8 segments: abrupt ending of pigment pattern / 0 - 8 / 0.1 / 0 - 0.8
Colours
White, red, light-brown (tan), dark-brown, blue-grey, black / 1 - 6 / 0.5 / 0.5 - 3.0
Differential structural components / 1 - 5 / 0.5 / 0.5 - 2.5
Total score / Benign / <4.76
Suspicious / 4.76-5.45
Melanoma / >5.45

Asymmetry = 0 /
Asymmetry = 1 /
Asymmetry = 2

Borders = 0 /
Borders = 4 /
Borders = 8

Colours = 1
Tan /
Colours = 3
Tan, dark brown, black /
Colours = 5
White, red, tan, dark brown, black

Blum's modified ‘ABC-point list’ is simpler to use:

·  A – asymmetry of outer shape or differential structures inside the lesion in at least 1 axis

·  B – the abrupt cutoff of network at the border in at least one quarter of circumference

·  C – 3 or more colors

·  D – 3 or more differential structures

·  E – noticed change (evolution) in the last 3 months

II. Menzies method

Menzies method to distinguish the dermoscopic features of benign melanocytic lesions from melanoma.

Negative features (benign lesions):

·  Symmetrical pattern (colours, structure)

·  Single colour

Symmetrical pattern /
Symmetrical pattern /
Single colour /
Single colour

Positive features (melanoma):

·  Blue-white veil

·  Multiple brown dots

·  Pseudopods

·  Radial streaming

·  Scar-like depigmentation

·  Multiple (5-6) colours

·  Multiple blue/grey dots

·  Broadened network

Blue-white veil /
Multiple brown dots /
Pseudopods /
Radial streaming

Scar-like depigmentation /
Multiple colours (5) /
Multiple blue/grey dots /
Broadened network

III. Seven-point rule

7-point checklist for the dermoscopic differentiation between benign melanocytic lesions and melanoma (scores in brackets). The scores should be added up. Three or more indicates melanoma.

1.  Atypical pigment network (2)

2.  Blue-whitish veil (2)

3.  Atypical vascular pattern (2)

4.  Irregular streaks (1)

5.  Irregular dots/globules (1)

6.  Irregular blotches (1)

7.  Regression structures (1)

Atypical pigment network /
Blue-whitish veil /
Atypical vascular pattern /
Irregular streaks

Irregular dots/globules /
Irregular blotches /
Regression structures

IV. 3 POINT CHECKLIST

The dermoscopy 3-point checklist for early detection of skin cancer is fairly easy to learn and has a high sensitivity for melanoma. (1) There a high likelihood of malignancy (melanoma or basal cell carcinoma) if a pigmented skin lesion has any two of these criteria. The 3-point checklist has been designed to allow non-experts not to miss detection of melanomas. However, it is not as specific as pattern analysis.

·  Asymmetry: asymmetry of colour and structure in one or two perpendicular axes

·  Atypical network: pigment network with irregular holes and thick lines

·  Blue-white structures: any type of blue and/or white colour, i.e. combination of blue-white veil and regression structures

The main aim of the 3-point checklist is to determine whether the lesion being examined should undergo a biopsy. It does not an require accurate diagnosis to be made as the finer features of the lesion are not examined.

Score = 0
Benign /
Score = 1
Benign /
Score = 2
Malignant /
Score = 3
Malignant
Symmetrical, uniform network, no blue-white structures. / Mild asymmetry of structure, no network, no blue-white structures. / Marked asymmetry of structure, network is ok, subtle greyish blue structure (arrow). / Mild asymmetry of structure, broad dark grey network which has blue-grey veil.

Symmetry

The following lesions demonstrate approximate symmetry of colour and structure. Shape is not considered.

Cherry angioma /
Compound naevus /
Compound naevus /
Cellular naevus

Solar lentigo /
Plantar naevus /
Benign naevus /
Seborrhoeic keratosis

The lesions below demonstrate asymmetry of colour or structure in one or two axes. Not all asymmetrical lesions are malignant.

Melanoma in situ /
Melanoma in situ /
Invasive melanoma /
Basal cell carcinoma

Plantar naevus /
Seborrhoeic keratosis /
Lentigo simplex /
Congenital naevus

Network

The following lesions are considered to have typical pigment network.

Junctional naevus /
Ephilis /
Benign naevus /
Junctional naevus

Ink spot naevus /
Plantar naevus /
Facial lentigo /
Dermatofibroma

The lesions below have atypical pigment network, with irregular holes and thick lines (broadened network). Streaming or pseudopods would also be considered atypical. Not all lesions with atypical network prove to be malignant.

Irregular pigment network: black arrows to broadened network, asterisk to streaming

Melanoma /
Lentigo maligna /
Melanoma in situ /
Lentigo maligna

Melanoma /
Lentigo maligna /
Lentigo maligna /
Atypical naevus

Blue-white structures

Blue-white structures can refer to any type of blue and/or white colour, i.e. combination of blue-white veil and regression structures, as shown in the following pictures. The colour can be subtle. Not all lesions with blue-white structures are malignant.

Melanoma /
Basal cell carcinoma /
Melanoma /
Lentigo maligna

Congenital naevus /
Blue naevus /
Dysplastic naevus /
Dysplastic naevus

V. PATTERN ANALYSIS

Benign melanocytic lesions

Global features

·  Reticular pattern (diffuse network)

·  Globular pattern (shades of brown)

·  Homogeneous pattern (diffuse colour)

·  Starburst pattern (uniform peripheral radial streaks, dots or globules)

·  Parallel pattern (along furrows; palms & soles only)

Reticular pattern /
Globular pattern /
Homogeneous pattern /
Starburst pattern

Local features

·  Pigment network, evenly spaced, fading out

·  Dots/globules distributed regularly

·  Streaks distributed regularly

·  Central hypopigmentation

·  Symmetrical blotches

·  Comma-like regular vasculature

·  On face: regular pseudonetwork

·  On palms/soles: Parallel furrow, lattice-like or fibrillar pattern

Fading pigment network /
Regular globules /
Regular streaks /
Central hypopigmentation

Symmetrical blotches /
Comma-like vasculature /
Symmetrical blotches/network /
Regular pseudonetwork

Parallel furrow pattern /
Parallel lattice pattern /
Parallel fibrillar pattern /
Parallel diffuse pattern

Melanoma

Global features

·  Multicomponent pattern (3 or more patterns)

·  Parallel pattern (along ridges; palms & soles only)

Global features of melanoma

Multicomponent pattern /
Multicomponent pattern /
Multicomponent pattern /
Parallel ridge pattern

Local features

·  Atypical pigment network (branched, broken-up, thickened, asymmetrical)

·  Dots/globules distributed irregularly and of different sizes and shapes

·  Asymmetrical blotches (featureless colours)

·  Focal irregular streaking or peripheral linear projections (radial streaming and pseudopods)

·  Five or six colours (black, brown, tan, grey, blue, red, white)

·  Blue-white veil over part of the lesion

·  White scar-like depigmentation

·  Blue pepper-like granules

·  Irregular linear or dotted vessels, or polymorphous vascular pattern especially with milky-red areas

·  On face: grey dots, pseudonetwork, rhomboidal structures, asymmetrical pigmented follicles, annular-granular structures

·  On palms/soles: parallel ridge, irregular

Atypical pigment network /
Irregular globules /
Asymmetrical blotches /
Focal irregular streaking

Five to six colours /
Blue-white veil /
Scar-like depigmentation /
Blue pepper granules

Irregular vessels /
Melanoma on the face /
Parallel ridge /
Asymmetrical blotches, dots

Pattern Analysis:

Structured approach to classify pigmented skin lesions according to dermatoscopic features

Colours

Black, dark or light brown, yellow

Combinations:

Purple globules and clods – Angioma

Blue globules and clods, brown background – BCC

Reticular, speckled – Junctional Clark’s nevus

Asymmetric, thick reticular lines – melanoma in situ

Central whiteness – Dermatofibroma

Comedo-like openings – milia cysts

Dotted Vessels

·  Melanocytic

o  Spitzoid lesions

o  Melanoma

·  Non-melanocytic

o  Bowen’s

o  Porokeratosis

o  Psoriasis

o  Clear cell acanthoma

o  Dermatofibroma

Melanocytic Patterns:

·  Diffuse, reticulated

·  Patchy

·  Peripheral network, central hyper or hypopigmentation

·  Homogenous

·  Reticulo-globular

·  Starburst

·  Globular

·  Multiple components

Melanoma

·  Atypical network

o  Thickened

o  Irregular

o  Branched streaks, broken ends

o  Peripheral dots

·  Radial streaming / pseudopods

o  Localised at peripheries, scar-like areas

·  Dots

o  Asymmetrical, off centre

·  Globules / Clods

o  Asymmetrically distributed peripherally

o  Reddish

·  Inverse pigment network

o  Track-like pattern

o  May be present in Spitz / Reed nevus

·  Chrysalis-like structure (octagonal white structures)

o  May be present in Spitz / Reed nevus

·  Blue veil in raised areas

·  Vascular pattern

o  Dotted, globular, polymorphic pattern – malignant

·  Blotchy tan-brown areas

ABCD checklist: A summary (Stolz et al, 1994 to now)

Total dermoscopy score (TDS) < 4.75 : Benign

4.75- 5.45: Borderline / Intermediate

>5.45 : Malignant

Asymmetry: 0-2 (x 1.3)

Border: Abrupt ending of pigmented patterns (0-8) (x 0.1)

Colour: White, red, light / dark brown, blue gray or black (x 0.5)

Dermatoscopic structures: network, dots, globules, streaks (x 0.5)

7-point checklist : A summary

MAJOR criteria (2 points)

·  Atypical network esp > 1 type

·  Atypical vessels

·  Blue white veil

MINOR criteria (1 point)

·  Regression structures

·  Irregular streaks

·  Irregular dots/ globules

·  Irregular blotches

Melanoma > 2 points

All single lesions with atypical pigment network should be excised

Blue white colour

·  Palpable: Blue white veil of melanoma

·  Non-palpable: Undergoing regression

Irregular branched streaks may be seen also in Spitz nevi or Spitzoid melanomas

CASH – colour , architecture, symmetry, homogeneity (BJD 2006)

NEGATIVE PREDICTORS OF MELANOMA (Arch Derm 2008)

Factor / Odds Ratio
Multiple milia like cysts
·  Congenital nevi, IDMN / 0.09
Comma vessels with regular distribution / 0.10
Comma vessels as predominant vessel type / 0.10
Symmetrical pigment pattern / 0.18
Irregular or multiple blue-grey nodules / 0.2

POSITIVE PREDICTORS OF MELANOMA

Factor / Odds Ratio
Blue white veil / 13
Scar-like depigmentation: Regression / 4.4
Multiple blue-gray clods / 3.5
Irregular-shaped depigmentation – Regression / 3.3
Irregular brown dots/globules / 3.2
5-6 colours / 3.2
Predominant central vessels / 3.1
Peripheral light brown structureless areas / 3
Ulceration / 3

Suspicious Vascular Structures:

·  Predominantly central vessels

·  Hairpin vessels

·  Milky red-pink areas

·  > 1 shade of pink

·  Combination of dotted and irregular linear vessels

·  Linear irregular vessels as predominant vessel type

Epithelial Neoplasms

Seb K

·  Pigmented

o  Pseudonetwork

o  Crypts

o  Milia-like cysts

o  Comedo-like openings

o  Keratin-filled holes

o  Fissures

o  Hairpin blood vessels

o  Sharp demarcation / obrder

o  Reticulation, network-like structures (NOT pigment network)

·  Flat

o  Moth-eaten border

o  Finger-print like structures

o  Brain-like appearance

o  Hairpin blood vessels only after trauma, surrounded by white halo

Solar Lentigo

·  Sharply demarcated irregular border

·  Fingerprinting

·  Moth-eaten border

·  Ring-like borders

·  Typical or atypical pigment network +/- regression

·  Ink-spot lentigo: black thick reticulated pigment network – lesions jump out at you

Lichen Planus - like Keratosis

·  Pinksh, moth-eaten borders +/- regression

·  Melanophages in dermis

·  Seb-K like

Angioma

·  Maroon lagoons

·  Partially thrombosed: Coagulated blood with black globules

Dermatofibroma

·  Central white patches

·  Ring-like globules

·  Thin reticulation at peripheral area

Others

Lichen Planus

·  Linear vessels / dotted vessels

·  Linear striae (Wickham’s)

·  Surface scales

Hypertrophic LP

·  Dotted vessels, whitish striae, surface scales

Ashy Dermatosis

·  Final phase of exanthemic LP?

·  Multiple grey granules

Tungiasis

·  Targetoid ring

·  Brown central border

·  Central brown pore filled with eggs

Psoriasis

·  Surface scales

·  Homogenously distributed small dotted vessels

Port Wine Stain

·  Superficial dots and globules

Clear Cell Acanthoma

·  Dotted vessels, pearly white background

MALIGNANT EPITHELIAL NEOPLASMS

1.  Pigmented: Vascular pattern + additional criteria

2.  Non-pigmented: Vascular pattern

5-step algorithm

·  Clinical : Single (tumour) vs Multiple (inflammatory)

·  Morphology: Type of vascular pattern

·  Architectural Vessel arrangement

§  Arborising / Branched (large stem, thin ramifications): Nodular, cystic BCC

§  Glomerular / Clustered : Bowen’s disease. DDX: Psoriasis

§  Hairpin / radial : SCC, KA

·  Additional dermatoscopic criteria

·  Diagnosis / Management

BCC: Nodular, cystic, sclerosing BCC have arborizing, dotted vsls with blue grey blotches

·  BCC: vessels in focus; Seb hyperplasia: vessels not in focus

Supf BCC – no arborizing vessels seen. Instead, short linear vessels, opaque red-white areas, and multiple small ulcerations / erosions are seen with brown-grey leaf-like areas, spoke-wheel pattern.

Pigmented Bowen’s : Clustered glomerular vessels, clustered brown dots a/w lines on whitish background

Keratoacanthoma / ulcerated SCC – Hairpin vessels a/w dotted, glomerular vessels with white halo, central keratin crust

DERMATOSCOPIC – PATHOLOGICAL CORRELATIONS

·  Branched streaks, atypical pigment network: junctional nests of melanocytes / melanophages

·  Black globules in melanoma – clumps of melanin in cornified areas

DERMATOSCOPY OF THE FACE

Features

·  Flattened rete ridges, numerous non-pigmented follicular openings

·  Characteristic network pattern not seen

Flat:

Solar lentigo

Lentigo maligna

Pigmented AK

Nodular:

Dermal Nevus

Seb Hyperplasia

BCC

Pigment deposition around hair follicles = pseudonetwork

Annular pattern: small circles surrounded by varying amounts of pigment

·  Clark nevus

·  Solar Lentigo

·  Early Seb K

o  Fine interrupted lines, early ridge formation, bulbous projections, milia cysts and comedo-like openings

·  Pigmented AK

·  Melanoma-in-situ / lentigo maligna

o  Annular-granular pattern -> rhomboidal structures -> homogenous aras

o  Short lines -> perifollicular invasion -> obliterated follicular openings

o  Slate grey -> Blue grey veil

·  LP-like keratosis

Reticular Pattern:

·  Solar lentigo

o  Fine thin lines, interrupted with fingerprinting, +/- moth eaten borders

FACIAL MELANOMA CRITERIA:

·  Global: Asymmetry, multiple colours

·  Local

o  Asymmetrical pigmented follicular openings

o  Irregular perifollicular hyperpigmentation

o  Circle within circle

o  Slate grey / blue grey granulating dots -> dermascopic regression