4 курс / Дерматовенерология / Дерматоскопия (3)

Figure 4.32: “Scar-like depigmentation”.

“Scar-like depigmentation” in a melanoma. In the language of pattern analysis this is simply a white structureless zone.

Figure 4.33: “Spoke-wheel areas”.

Dermatoscopic view of a basal cell carcinoma with a “spoke wheel” (arrow). In descriptive terminology this is described as radial lines converging at a central dot or a central clod.

known as a “central white patch” (see the respective sections). This is a further instance of the diagnosis influencing the description. In descriptive terminology we simply refer to either white structureless zones or white lines, as appropriate.

“Shiny white streaks, blotches and strands”

“Shiny white streaks” (19) correspond to perpendicular white lines in descriptive terminology. Former synonyms were chrysalis, chrysalids, or crystalline structures. The latter terms have been abandoned and should not be used even if you prefer metaphoric terminology. Shiny white blotches and strands correspond to white structureless areas, white clods, or thick white lines

(4.9). If lines are present they are usually oriented perpendicular to each other. These structures are seen only under polarized dermatoscopy and can be found in melanoma, basal cell carcinoma, Spitz nevus and dermatofibroma.

“Spoke-wheel areas”

Structures consisting of radial lines that converge at a central point or a central clod are known as “spokewheel areas” (4.33). They are very specific to basal cell carcinoma and are not seen in other lesions. The variant consisting of radial lines with a dot or a clod as a common center shows some similarity with spoke wheels when the radial lines completely surround the

central structure. Unfortunately, in many other cases they bear little similarity to spoke wheels. Usually the radial lines only partly surround the central structure. Another variant consists of a darkly pigmented dot in the center of a less heavily pigmented clod, reminiscent of a wheel, but without spokes. In any case the term “spoke wheel” is dispensable because these entities can also be described by the use of descriptive terminology.

“Starburst pattern”

The “starburst pattern” (8) is the combination of patterns consisting of a structureless zone centrally, with radial lines or pseudopods occupying the entire periphery

(4.34). This pattern is mainly found in Reed nevi and in those rare cases in which a melanoma mimics a Reed nevus. Occasionally the term “starburst pattern” is also used for a combination of clods at the periphery and a structureless hyperpigmented center. This pattern is more commonly found in the pigmented Spitz nevus. When two different patterns bear the same name, it is quite natural for the two different diagnoses – Reed nevus and pigmented Spitz nevus – to be lumped together.

“Strawberry pattern”

In metaphorical terminology this refers to a pattern which is sometimes seen in actinic keratoses in which

142 Metaphoric dermatoscopic terms and what they mean

Figure 4.37: “Targetoid vessels”.

Vessels as dots and coils in the hypopigmented area between reticular lines are sometimes called “targetoid vessels”. Their significance is unclear.

the dermatoscopic appearance is said to resemble the surface of a strawberry (29). In figure 4.35 there is a red background due to vascular erythema with keratin clods in the infundibulae rimmed by white circles. The resulting pattern is called “strawberry pattern”. The red background is not always seen. In the descriptive language we refer to this pattern as white circles against a red background.

“String of pearls”

The metaphor of “string of pearls” is used for coiled vessels that are arranged in serpentine lines (30). In the descriptive terminology we use the term “serpiginous” for this specific arrangement of vessels. It is rather specific for clear cell acanthoma although it has been described in other lesions too, most notably in prurigo or lichen simplex chronicus (4.36).

“Targetoid dots” and “targetoid vessels”

“Targetoid dots” and “targetoid vessels” refer to brown dots or red dots (vessels) in the center of hypopigmented space between reticular lines (4.37). These structures are found in some congenital nevi, especially larger ones, but their significance is unclear.

“Zig-zag pattern”

The term “zig-zag pattern” has been used for incomplete “rhomboids” on facial skin and corresponds to straight lines meeting at angles that form incomplete polygons around follicular openings (5) (4.30). They bear the same significance for facial melanoma in situ as “rhomboids”. For this reason we make no difference in the descriptive terminology and simply call this pattern “angulated lines”.

Metaphoric terminology

Annular-granular pattern Atypical pigment network Blotch

Blue-gray ovoid nests Blue-whitish veil, blue veil Branched streaks Broadened network Central white patch

Cerebriform pattern, fissures and ridges, gyri and sulci, fat fingers

Cobblestone pattern Comedo-like openings Crown vessels

Crypts

Delicate network Fibrillar pattern Fingerprinting Globules

Granularity or granules Homogenous pattern Lattice-like pattern (volar skin) Leaf like areas

Milia like cysts, cloudy or starry Milky red areas

Milky red globules Moth eaten border

Negative pigment network (synonyms: inverse network, reticular depigmentation)

Peppering Pigment network Pseudo-network Radial streaming Rainbow pattern Red lacunes Rhomboids Rosettes

Scar-like depigmentation

Shiny white blotches and strands

Shiny white streaks (synonyms: chrysalis, chrysalids, crystalline structure)

Spoke wheel area Starburst pattern Strawberry pattern Streaks

String of pearls Targetoid dots Zig-zag pattern

Descriptive terminology

Dots, gray and circles, gray

Lines, reticular and thick or reticular lines that vary in color

Structureless zone, brown or black

Clods, blue, large, clustered

Structureless zone, blue

Lines, branched

Lines, reticular and thick

Structureless zone, white, central

Lines, curved and thick

Clods, brown or skin colored, large and polygonal Clods, brown, yellow, or orange (rarely black) Radial linear vessels, not crossing the center

Lines, curved and thick, in combination with clods Lines, reticular and thin

Lines, parallel, short, crossing ridges (volar skin) Lines, brown, curved, parallel, thin

Clods, small, round or oval Dots, any color Structureless, any color

Lines, parallel, thin, in the furrows and crossing the ridges

Lines, radial, connected to a common base (sometimes variously shaped clods have been called “leaf like areas”)

Dots or clods, white, clustered or disseminated Structureless zone, pink

Clods, pink and small

Sharply demarcated, scalloped border

Lines, reticular, hypopigmented, around brown clods

Dots, gray Lines, reticular

Structureless, brown, interrupted by follicular openings (facial-skin) Lines, radial, peripheral and segmental

Structureless zone, polychromatic Clods, red or purple

Lines, angulated (facial skin)

Dots, white, four arranged in a square, 4-dot clod Structureless zone, white

Clods, white

Lines, white, perpendicular

Lines, radial, converging to a central dot or clod Pseudopods, circumferential or lines, radial, circumferential Structureless, red, interrupted by follicular openings

Lines, radial (always at periphery)

Coiled vessels arranged in serpentine lines

Dots, brown, central (in the center of hypopigmented spaces between reticular lines) Lines, angulated (facial skin)

References

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We now come to the core of the method, making a specific diagnosis. Pigmented skin lesions can be described very clearly and reliably using the method (patterns, colors and clues) described in the previous chapters. An exact morphological description is like a thread winding through a labyrinth; the thread leads a wandering or disoriented clinician safely to the outcome or exit. 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. Rules prescribe, at each turn, the direction one should take so that the clinician is not misled, as happens easily when using a method where descriptive terms are subjective, poorly defined, or dependent on diagnosis. Only after a comprehensive description and after all observable data have been taken into account are the findings interpreted and a specific diagnosis established.

The algorithm always takes the general form:

Pattern + Color + Clues = Diagnosis

The algorithmic method will be presented here in a stepwise manner. When you are confronted with an unknown pigmented lesion you may use the following pages as a classification reference guide. Using patterns, colors and clues, the number of potential diagnoses is progressively minimized. Finally just one or a few diagnoses remain. In those cases in which it is not possible to reach a confident specific diagnosis, the degree of doubt and the type of possible diagnoses will determine whether histopathology is required.

Pattern analysis is not an algorithm carved in stone, it is a method by which algorithms are constructed.

With experience, every investigator will develop their own individual algorithm. Only then does one become an expert. General criteria, guidelines and concepts are certainly required, but personal experience is also crucial. Beginners must rely on recipes, but experts personalize the recipe, refine and develop it further,

and so create their own style. Pattern analysis is the framework for developing this personal algorithm.

In every algorithmic method one makes decisions, which progressively reduce the number of differential diagnoses. In formulating the algorithmic method of pattern analysis, we attempted to fulfill the following basic principles: The criteria used to make decisions must be clearly and unambiguously defined. The criteria should be exclusive, i.e. the properties being assessed do not overlap, so unequivocal classification is possible. Decisions should be so simple that even beginners are able to perform the task. Decisions should show a high degree of concordance when judged by a range of clinicians. This decision process should be carried as far as possible – but no further!

The first step is to decide whether a pigmented lesion is composed of one or more than one pattern.

5.1 One pattern

The first step in pattern analysis of a pigmented lesion is to decide: is there one pattern or more than one pattern? This decision is nearly always both simple and unequivocal. When a pigmented lesion consists of just one pattern, then of course the next question is, which pattern? As we know, a pattern is formed by an aggregation of one of the five basic elements (lines, pseudopods, circles, clods and dots, 5.1). When basic elements are not seen or there are too few basic elements to constitute a pattern, the “pattern” is termed structureless. When evaluating patterns, individual dots or clods are not important; at this stage the general impression takes precedence. Once this decision is made, we progress through the algorithm in a stepwise manner, which divides into smaller and smaller branches with a progressively smaller differential diagnosis.

5.1.1 Lines

Lines may form six different patterns, created by differences both in the form of individual lines, and the arrangement of the lines relative to one another. These

patterns are reticular, branched, angulated, parallel, radial, and curved.

Reticular lines

Lesions that consist exclusively of reticular lines are extremely common. Although many algorithms use reticular lines as a criterion to diagnose lesions as melanocytic (1), lesions with reticular lines are not always melanocytic (2). In most cases the histological correlate of reticular lines is hyperpigmentation of basal keratinocytes on rete ridges, which may or may not be created by an increase in the numbers of melanocytes. As the next step the investigator assesses color (5.2). As melanin appears brown in the epidermis, reticular lines are usually light-brown or dark-brown. If the pigment is very dense, the lines are black. Rarely reticular lines are gray. Beginners are often too strict in assessing color and therefore tend to see too many colors. Not

every shade of brown is to be interpreted as a separate color. 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 than in the center; again this does not constitute an additional color.

If there is only one color, namely light-brown, and the lesion consists of thin reticular lines, the diagnosis is either junctional Clark nevus or solar lentigo (5.3). A Clark nevus is round or oval and the pigmentation does not end abruptly at the periphery. In contrast, the border of a solar lentigo is usually sharply demarcated and scalloped. A few brown dots may be found in both diagnoses, but more frequently in Clark nevus. It is not always possible to make a reliable distinction on dermatoscopy, but as both lesions are benign this is seldom crucial. Rare differential diagnoses for thin,