Analytic approach

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 Editor: Harald Kittler

 Author(s): Florentia Dimitriou     ·  Harald Kittler
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Description The analytic approachThis glossary term has not yet been described. refers to algorithmic method for the diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions of pigmented lesions using dermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections..

The essence of pattern analysisThis glossary term has not yet been described. is a structured description formulated using a clearly defined algorithmic method. The diagnostic method is structured in such a way that one starts by describing the most general of features, then proceeds progressively to finish with the most specific features. The algorithmIn mathematics and computer science, an algorithm (Listeni/ˈælɡərɪðəm/ AL-gə-ri-dhəm) is a self-contained sequence of actions to be performed. Algorithms can perform calculation, data processing and automated reasoning tasks. always takes the general form: Pattern + Color + CluesEvidence, in an investigation = Diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions Using patternsThis glossary term has not yet been described., colorsThis glossary term has not yet been described. and cluesEvidence, in an investigation, the number of potential diagnoses is progressively minimized. Pattern is a method by which algorithms are constructed.

Author(s) Florentia Dimitriou · Harald Kittler
Responsible author Harald Kittler→ send e-mail
Status released
Status update July 16, 2018
Status by Ralph P. Braun


The analytic approach refers to algorithmic method for the diagnosis of pigmented lesions using dermoscopy. The essence of pattern analysis is a structured description formulated using a clearly defined algorithmic method. The diagnostic method is structured in such a way that one starts by describing the most general of features, then proceeds progressively to finish with the most specific features. The algorithm always takes the general form: Pattern + Color + Clues = Diagnosis Using patterns, colors and clues, the number of potential diagnoses is progressively minimized. Pattern is a method by which algorithms are constructed.

It has the following subchapters:

Introduction to the analytic approach N.N.
Lines Harald Kittler, Florentia Dimitriou
Dots N.N.
Clods N.N.
Circles N.N.
Pseudopods N.N.
Structureless N.N.
Combination of pattern

Contents


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Introduction

The analytic approach is a dermoscopic algorithmic method for the diagnosis of pigmented lesions that is based on 5 basic geometric elements.

The essence of pattern analysis is a structured description formulated using a clearly defined algorithmic method. The diagnostic method is structured in such a way that one starts by describing the most general of features, then proceeds progressively to finish with the most specific features.

The algorithm always takes the general form:

Pattern + Color + Clues = Diagnosis

Using patterns, colors and clues, the number of potential diagnoses is progressively minimized.

Elements and patterns

The analytic approach builds on 5 Basic elements:

LinesstreaksThis glossary term has not yet been described.: structuresThis glossary term has not yet been described. with parallel edges, with their length much greater than their breadth

DotsDots are small, round structures of less than 0.1 mm in diameter that have a red color when corresponding to blood vessels; however, when due to melanin, their color ranges from black, brown, to blue-gray depending on the depth and concentration of the melanin in the skin (Tyndall effect).: circumscribed, small, round, indivisible pigmented structures with no length or breadth

ClodsThis glossary term has not yet been described.: solid, circumscribed, diversely formed pigmented or unpigmented structures larger than dotsDots are small, round structures of less than 0.1 mm in diameter that have a red color when corresponding to blood vessels; however, when due to melanin, their color ranges from black, brown, to blue-gray depending on the depth and concentration of the melanin in the skin (Tyndall effect)., with length and breadth

CirclesThis glossary term has not yet been described.: lines or collection of pigmented dots arranged sensibly equidistant from a common focal pointThis glossary term has not yet been described. that constitutes the center

PseudopodsBulbous and often kinked projections seen at the lesion edge, either directly associated with a network or solid tumor border.: short pigmented lines with a bulbous end

A pattern is formed by an aggregation of one of the five basic elements: linesstreaksThis glossary term has not yet been described., pseudopodsBulbous and often kinked projections seen at the lesion edge, either directly associated with a network or solid tumor border., circlesThis glossary term has not yet been described., clodsThis glossary term has not yet been described. and dots. Multiple repetitions of the same single basic element are required to constitute a pattern. This collection of basic elements should comprise a significant portion of the pigmented lesion (~ 25%). There are lesions with only one pattern and lesions with a combinationThis glossary term has not yet been described. of patterns.

When basic elements are not seen or there are too few basic elements to constitute a pattern, the "pattern" is termed structurelessThis glossary term has not yet been described..

Single Pattern

A minority of pigmented lesions present with only one pattern. The different patterns can be grouped based on the geometric elements comprising them:

Lines

Lines may form six different patterns, depending on their shape and arrangementThis glossary term has not yet been described.: reticular, branched, angulated, parallel, radial, and curved.

Reticular linespigment network melanocytic lesions dermatofibroma solar lentigo

Straight lines crossing each other at an angle of 90° forming a greed are termed reticular linespigment network melanocytic lesions dermatofibroma solar lentigo. Lesions with reticular lines are not always melanocyticThis glossary term has not yet been described.. In most cases the histological correlate of reticular lines is hyperpigmentation of basal keratinocytes, which may or may not be created by an increase in the numbers of melanocytes.

ColorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue.

  • Usually light-brown or dark-brown, due to melanin in the epidermis.
  • If the pigment is very dense, the lines are black.
  • Rarely, they can appear gray.

Not every shade of brown is to be interpreted as a separate colorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue.. One or two black lines do not render the lesion multicolored. The normal hypopigmentation around follicular openings does not create an extra color. Nearly all pigmented lesions are somewhat lighter at the periphery compared to their center.

Light-brown + thin reticular lines

Junctional Clark nevus or solar lentigoThis glossary term has not yet been described..
A Clark nevus is round or oval and the pigmentation does not end abruptly at the periphery. The border of a solar lentigo is usually sharply demarcated and scalloped.
Differential diagnoses: a variant of dermatofibromaDermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma. with only reticular lines and urticaria pigmentosa, a type of mastocytosisThis glossary term has not yet been described..

Brown + thick reticular lines

Clark nevus or superficialThis glossary term has not yet been described. congenital nevusThis glossary term has not yet been described..
Differential Diagnoses: Solar lentigoThis glossary term has not yet been described., seborrheic keratosisThis glossary term has not yet been described..


Black (very dark-brown) reticular lines

Ink-spot lentigo. No differential diagnosis needs to be considered. Very rarely a Reed nevusThis glossary term has not yet been described. may demonstrate this pattern and color combination, but without the additional clues to "ink-spot lentigo"

More than one color + reticular lines

Solar lentigo or seborrheic keratosis.

  • Clues to solar lentigo: well-demarcated, scalloped border.
  • Clues to seborrheic keratosis: white dots or clods, orange or yellow clods, well-demarcated border, circles, thick curved lines, vesselsThis glossary term has not yet been described. as loops or coils.
  • Differential diagnoses: Clark nevus, superficial or superficial and deep congenital nevus, and melanomaThis glossary term has not yet been described. in situThis glossary term has not yet been described..

Dark-brown or black and light-brown areas: variegate color distribution

  • Differential diagnosis: Clark nevus, superficial / superficial and deep congenital nevus, or melanoma in situ
  • Only 5 of the 8 clues to melanoma are seen in reticular pattern lesions:
  1. gray dots, clods, circles or lines;
  2. radial lines or pseudopods seen only in some segments of the periphery;
  3. black dots or clods at the periphery;
  4. thick reticular lines and angulated lines (polygonslines angulated or polygonal (non-facial skin)). When one of these clues is present, the diagnosis of melanoma should be seriously considered;
  5. Eccentric hyperpigmentation ,i.e. the more heavily pigmented area is not in the center but the periphery- can be seen in Clark neviThis glossary term has not yet been described. and melanomas in situ, rarely in congenital neviis a type of melanocytic nevus (or mole) found in infants at birth. This type of birthmark occurs in an estimated 1% of infants worldwide; it is located in the area of the head and neck 15% of the time..
    Differential diagnosis: Invasive melanoma. When no clue to melanoma is present, a Clark nevus is the most likely diagnosis.

Branched lines

Branched lines and reticular lines are closely related and often occur together. Unlike reticular lines that cross each other at a 90° angle, branched lines are straight lines crossing each other in different angles. Lesions that are exclusively composed of branched lines are either black or brown, and they are all benignis any condition that is harmless in the long run.

Brown branched lines: Clark nevus or superficial / superficial and deep congenital nevus.
Black (or very dark-brown) branched lines: ink-spot" lentigo.

Angulated linesSyn: polygons, zig-zag pattern Gray-brown lines that are connected at an angle or coalescing to form polygons

Angulated lines are pigmented lines that form angles.

  • May appear on facial skinThis glossary term has not yet been described. and on non-facial skin.
  • Are the hallmark of flat melanomas on chronic sun-damaged skinThis glossary term has not yet been described..
  • Most melanomas with angulated lines are not invasive (in situ).
  • They are usually brown or grey.

Parallel lines

Parallel lines are straight lines that don't cross each other.

  • Typical pigment pattern of acralPertaining to peripheral body parts, especially hands, feet, fingers, and toes. skin.
  • They may be arranged in one of three ways; on the ridges (ridgeThis glossary term has not yet been described. pattern), in the furrows (furrow pattern), or crossing ridges (crossing pattern).
  • AcralPertaining to peripheral body parts, especially hands, feet, fingers, and toes. lesions that only show a pattern of furrows or a crossing pattern may be safely considered to be benign.
  • Assessment of a lesion showing the ridge pattern proceeds by evaluating color.
  • If it is brown, in situ melanoma must be considered. Black, red or purple parallel lines on the ridges indicate either hemorrhage or exogenous pigmentation. Satellite clods are a strong clue to the diagnosis of hemorrhage.

Radial lines

Radial lines are staright lines that converge to the center of a lesion or to a central dotSee [[Glossary:Dots|Dots]] or clod.

  • They always occur in combination with another pattern.

Curved lines

Curved lines are lines that bend and are not straight.

  • They usually occur in combination with other patterns.
  • can be seen in seborrheic keratosis and solar lentigo.

Pseudopods

Pseudopods are short pigmented lines with a bulbous end and are often kinked. They are seen at the lesion edge, either directly associated with a networkThis glossary term has not yet been described. or solid tumor border.

  • They occur only in combination with other patterns.

Circles

It is the pattern of facial skin, but also not unusual at other locations on the body.

On the faceis a central body region of sense and is also very central in the expression of emotion among humans and among numerous other species., they are formed by melanin pigment arranged either around the openings of the crater-like infundibula or in infundibular epithelium. The center of the infundibulum appears hypopigmentedThis glossary term has not yet been described.. If infundibula contain keratinized material the hypopigmented center is seen as a yellow or orange clod. Circles may be brown, gray or black.

Brown circles

Are found solar lentigo or flat seborrheic keratosis.

Gray circles on facial lesions

Are found in melanoma in situ. Differential diagnoses: lichen planusThis glossary term has not yet been described.-like keratosis, pigmented actinic keratosisActinic keratosis (also called solar keratosis and senile keratosis; abbreviated as AK) is a pre-cancerous patch of thick, scaly, or crusty skin..

Circles On the trunk or the extremities

This pattern of circles may be a variant of the reticular patternA lesion with a reticular pattern has typical pigment network throughout the entire lesion.. Differential diagnoses: junctional Clark nevus, solar lentigo, and dermatofibroma.

Clods

After reticular lines, the pattern of clods is the second most common.

Clods can be classified based on the predominant color/ colors.It is necessary to distinguish between the colors of melanin and the colors of other pigments. Clods whose pigmentation is due to melanin are either brown, blue or gray.

Clods with one predominant color:

White and/or yellow clods

Are often found in seborrheic keratosis and represent dilated infundibula and inclusion cysts ("milia") filled with keratin. If they are accompanies by radial vesselscrown vessels Radial serpentine or arborizing vessels at the periphery of the lesion that radiate towards the center but do not cross the midline od the lesion. sebaceous hyperplasia that do not cross the center of the lesion sebaceous gland hyperplasia should be considered.

Orange clods

Can be seen in seborrheic keratosis, or basal cell carcinomais the most common skin cancer, and one of the most common cancers in the United States.[1] While BCC has a very low metastatic risk, this tumor can cause significant disfigurement by invading surrounding tissues (orange clods due to ulceration (serum crust)). Whereas multiple orange clods are seen in seborrheic keratosis, in basal cell carcinoma one usually finds one or two orange clods with traces of red due to red blood cells in the serum crust. A further clue to the diagnosis is the pattern of vessels: in basal cell carcinoma the vessels are serpentine, often branched; in seborrheic keratosis the vessels are looped or coiled (or rarely serpentine).

Red or purple clods

Are found in hemangiomaThis glossary term has not yet been described. or vascular malformations.

Black clods

Represent thrombosed vessels

Red clods

Represent hemorrhage

Large, polygonal skin-colored clods

Are seen in exophytic congenital nevi with papillomatous surface (Unna nevus or Miescher nevus), or verrucous seborrheic keratosis.

Brown clods

Are seen in various types of melanocytic nevi.

Large, polygonal light-brown clods

Are seen in Unna nevus or Miescher nevus

Small to medium-sized, round and oval brown clods

Small congenital nevi of superficial and superficial and deep types. Central hyperpigmentation is common in pigmented Spitz neviThis glossary term has not yet been described., and peripheral clods are usually smaller than those in the center.

Blue clods

Are seen in pigmented basal cell carcinomaThis glossary term has not yet been described..Differential diagnoses: melanoma and combined congenital nevus.

Clods with more than one predominant color:

White, yellow or orange clods

Keratin with (orange) or without (white or yellow) inclusions of melanin. Orange clods may also result from ulceration (serum crust).

White or yellow clods

Are mainly found in seborrheic keratosesThis glossary term has not yet been described. and less often in Unna nevi. Orange clods also indicate a seborrheic keratosis or less often an Unna nevus.

CombinationThis glossary term has not yet been described. of red, purple or black clods

HemangiomaThis glossary term has not yet been described., vascular malformation or hemorrhage.

Melanin colors (brown, blue or gray) clods with symmetrical color distribution

MelanocyticThis glossary term has not yet been described. nevi, i.e. superficial and deep congenital nevi, combined congenital nevi, Unna nevi and pigmented Spitz nevi

Melanin colors (brown, blue or gray) clods with asymmetrical color distribution

Pigmented basal cell carcinomaThis glossary term has not yet been described. and melanoma.

Dots

Dots, like the rest of the elements, are grouped based on their color. Dots usually occur in combination with other patterns. Only gray or brown dots are found in lesions without another pattern. Only red dots: are found in non-pigmentedThis glossary term has not yet been described. lesion, i.e. vessels as dots.

Gray dots

Are found in lichen planus-like keratosis, pigmented actinic keratosis, pigmented Bowenalso known as squamous cell carcinoma in situ[1] is a neoplastic skin disease. It can be considered as an early stage or intraepidermal form of squamous cell carcinoma. It was named after John T. Bowen’s disease and melanoma.

  • Lichen planusThis glossary term has not yet been described.-like keratosis: curved lines or typical sharply defined and scalloped border. On chronic UV-exposed sites (face or the dorsum of the hand).
  • Pigmented actinic keratoses: on the face. Usually seen as gray circles
  • Pigmented Bowen’s disease: on the trunk and extremities. It may mimic other lesions, but the clues of coiled vesselsglomerular vessels tightly coiled vessels resembling the glomerular apparatus of the kidney Bowen disease and dots arranged as lines lead to the correct diagnosis.
  • In situThis glossary term has not yet been described. melanomas: gray dots mixed with brown dots. Random distribution, arranged as circles around the openings of the infundibula (face), or lines arranged as polygons (trunk or extremities)

Brown and small gray dots

Are found in clark nevus, or rarely in solar lentigo and pigmented Bowen’s disease.

Brown and red dots

Are found in inflammatory skin diseases with extravasation of red blood cells, e.g. pigmented purpuric dermatosis.

StructurelessThis glossary term has not yet been described.

Definition: no basic elements, too few to constitute a pattern, or the visible structures cannot be assigned to one of the five basic elements.

Lesions that only have a structureless pattern are difficultneeding much effort or skill to accomplish to diagnose using dermatoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. and often require histopathologyThis glossary term has not yet been described..

One color predominates over all othersThis glossary term has not yet been described.This glossary term has not yet been described.

Black + structureless

Usually represents the presence of hemoglobin (not melanin) and its degradation products, e.g. hemorrhagic crusts, hemorrhages in the epidermis and thrombosed vessels. Differential diagnoses: heavily pigmented melanocytic lesions, e.g. Reed nevus, Clark nevus or melanoma.

Blue + structureless

"Blue nevi" of all types. Differential diagnoses: melanomas, melanoma metastases, structureless blue pigmented basal cell carcinomas.

Brown + structureless

Can be seen in solar lentigo, flat seborrheic keratosis, pigmented Bowen’s disease, and melanocytic nevus of superficial or superficial and deep congenital type.

Red + structureless

This pattern represents recent hemorrhage in the stratum corneum. It will become a black structureless lesion as the hemoglobin degrades, before it entirely disappears due to transepidermal elimination.


More than one color

It can be difficult to differentiate between clods or structureless. Clods: are well circumscribed and always occur in numbers while Structureless is one large contiguous area.

ColorsThis glossary term has not yet been described. of keratin (yellow and orange)

Are seen in keratinizing lesions such as seborrheic keratosis. Differential diagnoses: basal cell carcinoma.

Colors of hemoglobin (red and purple)

Represent hemorrhage that can also occur in a pre-existing lesion such as a nevus.

Black zones in structureless lesion

Black color should be attributed to blood (thrombosis) when it appears together with red or purple and attributed to melanin when it appears together with brown, blue or gray.

Colors of melanin (black, brown, blue)

  • Symmetrical distribution of melanin: nevus.
  • Asymmetrical distribution of melanin: melanoma, melanoma metastasis, seborrheic keratosis.
  • Differential diagnosis: pigmented basal cell carcinoma or a dermatofibroma.

Multiple patterns

The majority of pigmented lesions have more than one pattern. The diagnostic algorithm for pigmented lesions with multiple patterns depends on the type of patterns that are present in the lesion. First, if "lines" are present - the algorithm of "lines" should be followed. If "lines" are not present, the investigator should look next for "pesudopods" and follow their algorithm. This process continues sequentially through "circles", "clods" and finally "dots".

Structural symmetry

The combination of patterns should be assessed for symmetry. Symmetry is judged based on the distribution of patterns and colors within the lesion. The more patterns, the less symmetric the lesion is. There are two ways in which two patterns can be combined symmetrically:

  1. One pattern is in the center and the other at the periphery
  2. The basic elements of one pattern (e.g. dots) are regularly spread over a second pattern (e.g. reticular lines).

All other combinations of two patterns are, by definition, considered asymmetrical.

Lines

Reticular and/or branched lines

Reticular lines are much more common than branched lines.


Sharply demarcated patterns

  • Sharply demarcated scalloped bordermoth eaten border solar lentigo + curved lines: solar lentigo or lichen planus-like keratosis.
  • Sharply demarcated borderThis glossary term has not yet been described., white dots or clods, yellow or orange clods + thick curved lines: seborrheic keratosis.


Symmetrical patterns

  • Clods in the center + reticular lines at the periphery: superficial or superficial and deep congenital nevus, Clark nevi.
  • Reticular lines in the center + clods (or dots) peripherally: Clark nevus in phase of growth, or growing superficial or superficial and deep congenital nevus.
  • Reticular lines + uniformly distributed clods (or dots): Clark nevi or superficial or superficial and deep congenital nevi.
  • Symmetrical combination of pseudopods (i.e. the pseudopods are seen occupying the entire circumference): Reed nevus.
  • Symmetrical combination of peripheral radial lines: Reed nevus, or Clark nevus.
  • Symmetrical combinations of three patterns, e.g. structureless in the center and reticular lines and dots or clods at the periphery: superficial and superficial and deep congenital nevi

Symmetrical color

  • SkinThis glossary term has not yet been described.-colored: raised and papillomatous. Most commonly in superficial and deep congenital nevus, less frequently in Clark nevus.
  • Dark-brown or black: Clark nevus, or rarely Reed nevus.
  • Blue: combined congenital nevus, or less often Reed nevus.
  • White: dermatofibroma.

Asymmetrical patterns

  • Asymmetrical combination of patterns: usually exclusively brown and likely to be a nevus (Clark nevus or superficial or superficial and deep congenital nevus).
  • Asymmetrical lesions with more than one pattern (most lesions) should be assessed for clues to melanoma.

Parallel lines

Commonly seen in acral pigmented lesions. They may appear on the ridges, in the furrows, or crossing ridges and furrows.

RidgeThis glossary term has not yet been described. pattern

  • It takes precedence if more than one parallel line pattern is seen.
  • If pigmentation on the ridges is in the colors of melanin, the diagnosis of melanoma must be considered. Hemorrhage or exogenous pigmentation are the likely diagnoses when colors other than those of melanin are seen.\

Pattern of furrows or crossing pattern

Distinction between symmetrical and asymmetrical is necessary.

  • Symmetrical combinations: classic acral nevi and other nevi, e.g. Reed nevi or superficial and superficial and deep congenital nevi.
  • Asymmetrical combinations: clues to melanoma.

Radial lines

Always occur in combination with other patterns.

Symmetrical patterns

Radial lines occupy the entire circumference of the lesion.

  • Structureless center + white: dermatofibroma.
  • Structureless center + brown, black or gray: Reed nevus.

Asymmetrical patterns

Peripheral radial lines do not occupy the entire circumference of the lesion but are present only in some segments. The primary differential diagnosis includes melanoma versus basal cell carcinoma. In basal cell carcinoma arrangements of radial lines usually have a common base. The radial lines are not only seen at the periphery but also within the lesion.

Curved lines

The least specific pattern. Lesions are almost always asymmetrical.

  • Brown color: solar lentigo, seborrheic keratosis.
  • Colors of melanin (gray, blue or black): melanoma, seborrheic keratosis, lichen planus-like keratosis.

Pseudopods

Psueodopods are only seen in combination with another pattern. Most commonly pseudopods are at the periphery with other pattern in the center of the lesion: structureless, clods, or reticular lines.

Symmetrical pattern

Regularly distributed pseudopods in the periphery, e.g. Reed nevus.

Asymmetrical pattern

MelanomaThis glossary term has not yet been described. must be considered. Patient’s ageprocess of becoming older, skin typeThis glossary term has not yet been described., number of nevi, distribution of pseudopods, clinical appearance and history of change are relevant to the diagnosis.


Circles

This is a typical pattern of facial skin.

Symmetrical pattern

Peripheral brown circles combined with a structureless zone (or less often white lines) centrally, e.g. dermatofibroma.

Asymmetrical pattern

Pattern of circles with no lines. The color of the circles becomes more important than assessment of symmetry:

  • Brown: solar lentigo, seborrheic keratosis, superficial or superficial and deep congenital nevus, Clark nevus, Miescher nevus.
  • Gray or black: melanoma, lichen planus-like keratosis and pigmented actinic keratosis.


Clods

Clods + structureless: combined symmetrically or asymmetrically:

Symmetrical pattern

Structureless zone in the center of the lesion and clods at the periphery.

  • Skin-colored center: SuperficialThis glossary term has not yet been described. and deep congenital nevus, Spitz nevusThis glossary term has not yet been described..
  • Brown or black center: Growing superficial and deep congenital nevus (commonly in children), pigmented Spitz nevus.
  • Blue structureless center: Combined congenital nevus.

Asymmetrical pattern

Contains clods but no lines, Pseudopods or circles. These lesions are analyzed depending on whether the colors are predominantly those of melanin, or of another pigment:
(a) Lesions with melanin pigment are predominantly black, brown, gray or blue

  • Black pigmentation: coagulated blood or melanin. The interpretation depends on what other colors are present.
  • Brown, blue or gray: melanin in the stratum corneum.
  • Red or purple: coagulated blood.
    When melanin is the predominant pigment, the color of the whole lesion should be assessed:
  • Brown color: superficial and deep congenital nevus or a Spitz nevus.
  • Other colors: basal cell carcinoma, melanoma, seborrheic keratosis and its variants.

(b) Lesions with no pigment, or with pigments other than melanin are assessed based on the color of the clods:

  • White or yellow clods: seborrheic keratosis.
  • Orange clods: seborrheic keratosis, basal cell carcinoma.
  • Red or purple clods: hemangioma, vascular malformation, melanoma or melanoma metastasis.

Dots

Dots and structureless

The algorithm for "dots and structureless" differs only slightly from the algorithm for "dots":

  • Gray dots: melanoma, lichen planus-like keratosis, pigmented superficial squamous cell carcinomaThis glossary term has not yet been described. (actinic keratosis or Bowen’s disease), basal cell carcinoma.
  • Blue dots: basal cell carcinoma.
  • Black dots: uncommon; exclude melanoma.
  • Brown dots: solar lentigo, pigmented Bowen’s disease, Clark nevus.


ReferencesThis is material contained in a footnote or bibliography holding further information.:

  1. Kittler. DermatoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.: introduction of a new algorithmic method based on pattern analysis for diagnosis of pigmented skin lesions. DermatopathologyA joint subspecialty of dermatology and pathology and to a lesser extent of surgical pathology that focuses on the study of cutaneous diseases at a microscopic and molecular level. It also encompasses analyses of the potential causes of skin diseases at a basic level. Dermatopathologists work in close association with clinical dermatologists. In fact, most of them are trained primarily in dermatology themselves.: Practical & Conceptual, 2007
  2. Kittler et al. Standardization of terminology in dermoscopy/dermatoscopy: Results of the third consensus conference of the International Society of DermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.. J Am Acad Dermatol. 2016 June ; 74(6): 1093–1106.
  3. Kittler et al. Revised version of pattern analysis. In Marghoob et al. Atlas of Dermoscopy, Second Edition. Informa healthcare, London, 2012.