4 курс / Дерматовенерология / Дерматоскопия (3)
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Figure 8.21: Nevi on the face.
In addition to Miescher nevi, other nevi – primarily congenital ones – may occur on the face. The general diagnostic method of dermatoscopy (pattern + color + clues = diagnosis) applies regardless of the location on the face. Top: A brown and blue structureless lesion in which the colors are arranged asymmetrically must be excised in order to exclude a melanoma. Histopathological diagnosis: Combined congenital nevus. Middle: One pattern, structureless, one color, blue – these are clues to a blue nevus. Bottom: One pattern, clods, more than one color, brown and gray, with the colors arranged symmetrically, are most likely indicative of a nevus. Histopathological diagnosis: “Superficial and deep” congenital nevus.
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Figure 8.22: Facial seborrheic keratosis.
A flat seborrheic keratosis that shows a reticular pattern on dermatoscopy (right). The color is only brown. Note that other clues to seborrheic keratosis are missing. There are no white dots or clods and the border is not sharply demarcated.
A B
C D
E F
Figure 8.23: Schematic presentations of patterns of flat facial pigmented lesions.
A: Circles. B: Dots. C: Structureless. This pattern has been termed “pseudo-pigment network”, a term which is discouraged because it is misleading – the pattern is structureless, not “network”. D: Angulated lines (polygons). E: Curved lines. F: Reticular lines.
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Figure 8.24: Common patterns of facial solar lentigines on dermatoscopy.
Top left: Solar lentigo with a reticular pattern. There are also some brown circles. Note that some of the brown circles are incomplete (“asymmetric follicular openings”), which is not a specific clue in this context. There is no gray. Top right: A solar lentigo with a reticular pattern. There are also some brown dots and small clods, which indicate a transition to a flat seborrheic keratosis. Bottom left: Solar lentigo with curved lines. Note that the color is only brown and the sharply demarcated scalloped border, which is also a clue to solar lentigo. Bottom right: Solar lentigo with structureless pattern. The color is only brown. The sharply demarcated scalloped border is another clue to solar lentigo.
Figure 8.25: Subtle gray circles in a melanoma in situ.
Clinically (left) this is an inconspicuous brown macule. On dermatoscopy (right) one finds discrete gray circles (arrows). The histological diagnosis is in situ melanoma.
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Figure 8.26: Three facial melanomas in situ with circles as the main pattern.
Dermatoscopy on the right. Top, middle: In situ melanomas with gray and brown circles. Bottom: An in situ melanoma with brown circles only.
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Figure 8.27: A facial melanoma with more than one pattern.
Dermatoscopy on the right. Melanoma with circles (upper part) and angulated lines (left lower part). The more advanced right lower part shows a structureless pattern.
the pattern of circles usually remains visible in other parts. Sometimes the circles in melanoma in situ are brown and not gray (8.26 bottom) and then it can be very difficult to differentiate melanoma in situ from solar lentigo. In solar lentigo, however, other clues are usually present such as reticular and curved lines and a sharply demarcated, scalloped border. Although some say incomplete circles (“asymmetric follicular openings”) are a clue to melanoma in situ, we consider this feature of limited value because incomplete circles are commonly found in solar lentigines and in pigmented actinic keratoses (i.e. the clue has poor specificity). A circle in a circle (concentric circles) is a quite specific clue to facial melanoma in situ, but it is rarely present (i.e. the clue has poor sensitivity) (8.28). Furthermore, this clue is usually found in larger lesions with other (less subtle) clues which make the diagnosis of melanoma obvious. In a study by Tschandl et al (16) the clue of “circle in a circle” was found in only 4.2 % of facial flat melanomas.
Similar to flat melanomas on chronic sun damaged non-facial skin, the pattern of angulated lines is also common in facial melanoma in situ (8.29, 8.30). (16) However, on the face, angulated lines are not
highly specific for melanoma; they are also found in pigmented actinic keratoses and lichen planus-like keratosis. Facial angulated lines probably correspond to what has been previously described as rhomboids by Stolz et al. (15)
Although gray pigmentation may appear in benign facial lesions (as in lichen planus-like keratosis) it is an important clue to malignancy in flat lesions (8.31). In a study by Tschandl et al (16) the sensitivity of gray pigmentation for melanoma in situ was 96 % and the specificity was 31 %.
Because of the rather poor specificity, the decision to biopsy a lesion should not be based on the clue of gray pigmentation alone. Other clues including the presence or absence of benign clues (for example clues to solar lentigo) should be also considered. However, if gray circles are present, especially if the circles are thin, the diagnosis of melanoma in situ (lentigo maligna) should be favored over the other diagnoses.
Pigmented actinic keratoses are common on facial skin and can mimic melanoma in situ (8.32). Clues to pigmented actinic keratosis are scale, background erythema, white circles, and, although less specific,
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Figure 8.28: Two facial melanomas with the clue of “circle within a circle”.
Dermatoscopy on the right. Melanoma with concentric circles (circle within a circle) on dermatoscopy (black arrows).
four dots in a square. Pigmented actinic keratosis may show many patterns including circles, structureless, dots and even reticular and curved lines. Reticular and curved lines in a pigmented actinic keratosis usually indicate a collision with solar lentigo. Lichen planus-like keratosis may also mimic facial melanoma in situ. Lichen planus-like keratosis is a solar lentigo in the stage of regression (8.33). As a consequence of inflammation, melanophages accumulate in the papillary dermis and appear as grey dots under the dermatoscope. Hence these lesions are frequently biopsied. The gray dots in lichen-planus like keratosis are usually distributed between the follicular openings (8.33 bottom) and not arranged in circles around follicular openings.
Other parts of the lesion may show remnants of a solar lentigo. Angulated lines may occur in lichen planus like-keratosis but only rarely and usually only
in the part of the lesion in which regression occurs
(8.33 top).
While Clark nevi may mimic melanoma in situ, they are very rare on facial skin. Clinicians should be very reluctant to accept a histopathologic diagnosis of Clark nevus (often referred to as “dysplastic” nevus) on facial skin, especially if the diagnosis is based on a partial biopsy. Dermatopathologists may err too.
Collisions are very common on the face. Melanoma in situ, solar lentigo and actinic keratosis are all common lesions on chronic sun damaged skin, meaning collisions will occur by chance.
Histopathologically, solar lentigines are commonly found adjacent to facial melanomas in situ, but this does not prove a causal relationship between solar lentigo and melanoma in situ, as has been proposed in the concept of “unstable lentigo”. Solar lentigines are also found in conjunction with actinic keratoses,
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Figure 8.29: Facial melanomas (in situ) with angulated lines.
Dermatoscopy on the right. Top: Melanoma in situ with angulated lines. Note that there is only very subtle gray color. Middle: Melanoma in situ with angulated lines, some of which are gray. Bottom: Melanoma in situ with gray dots and angulated lines.
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Figure 8.30: Melanoma in situ with angulated lines as the only clue.
Melanoma in situ with angulated lines as the main pattern. The color is brown. Note that there are no clues that point to solar lentigo (such as a sharply demarcated scalloped border). In more difficult lesions, the absence of benign clues may raise suspicion that one is dealing with a melanoma in situ.
Figure 8.31: Gray structures as a clue to facial melanoma.
Clinical left column, dermatoscopy right column. The general diagnostic method of dermatoscopy (pattern + color + clues = diagnosis) applies regardless of the location on the face. Top: One pattern, reticular, more than one color, variegate, gray lines and circles as clues to melanoma, lead to the diagnosis of an in situ melanoma. Bottom: More than one pattern, clods and structureless, arranged asymmetrically, gray clods and dots as a clue to melanoma, lead to the diagnosis of melanoma. Note that in both cases, there are no clues to a benign lesion.
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Figure 8.32: Pigmented actinic keratosis.
Two pigmented actinic keratoses with a pattern of angulated lines. Additional clues to pigmented actinic keratosis are white circles (left), and white circles, scale and background erythema (right).
Figure 8.33: Solar lentigines with regression (Lichen-planus like keratosis).
Clinical left column, dermatoscopy right column. Top: Solar lentigo in regression (lichen planus-like keratosis) with a structureless brown pattern and a few brown circles at the periphery. In the center one can see gray structures which are best described as angulated lines. A typical feature of solar lentigo is the sharply demarcated scalloped margin. However, a biopsy is required to rule out an in situ melanoma. Bottom: Solar lentigo in regression (lichen planus-like keratosis) with a few gray dots and lines in the upper part of the lesion. Note that the grey dots are distributed between the follicular openings and not around the follicular openings. A biopsy or examination with reflectance confocal microscopy is required to exclude an in situ melanoma.
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Figure 8.34: Dermatoscopy of mucosal lesions.
Clinical left column, dermatoscopy right column. Top: Typical labial lentigo. On dermatoscopy one finds curved lines and circles which is a common pattern on mucosal sites. Middle: Penile lentiginosis with multiple light brown and dark brown macules. On dermatoscopy one finds brown circles and a brown structureless area but no gray, blue, black or white areas. Bottom: Vulvar melanoma that is already clinically obvious. On dermatoscopy one finds a large black and blue structureless area located eccentrically which is a clue to melanoma.