4 курс / Дерматовенерология / Дерматоскопия (3)
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Figure 7.6: Double reticular lines as a clue to Clark nevus.
Clinical (top left) and dermatoscopic (top right) view of a Clark nevus. At high magnification (bottom row) double reticular lines throughout the lesion are obvious. The double lines have a small hypopigmented space between them.
Figure 7.7: Four dots in a square (four-dot clod) as clue to actinic keratosis or superficial squamous cell carcinoma.
Left: With polarized light the 4-dots are seen very clearly on the pigmented portion of this actinic keratosis. Right: Four dots in a square as a clue to superficial squamous cell carcinoma (Bowen’s disease) in this case in collision with a solar lentigo which accounted for the reticular lines.
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Figure 7.8: Thin gray circles as a clue to melanoma in situ.
Clinically this pigmented macule on the nose looks insignificant (A). Dermatoscopically (B, C) there are only thin gray circles on a brown structureless background. This is not the pattern of lichen-planus-like keratosis or pigmented actinic keratosis. Excision biopsy revealed it to be an in-situ melanoma.
Figure 7.9: White lines.
Short white lines in an invasive melanoma arising in a pre-existing nevus (dermatoscopy on the right).
clod. In the appropriate context it is a clue to actinic keratosis or superficial squamous cell carcinoma but it is not as specific as initially thought. It can even be found on normal skin.
Gray circles versus gray dots on the face
We consider that any dermatoscopic gray in head or neck lesions should be regarded as a clue to melanoma (5), with a differential diagnosis of lichen planus-like
keratosis and pigmented actinic keratosis. When the gray is seen as thin gray circles, this is a far stronger clue to melanoma than gray dots, even when the dots are arranged as circles (7.8).
White lines
White lines may be short or long, thin or thick. They may be arranged in a reticular pattern or perpendicular to each other but without crossing each other. Reticular
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Figure 7.10: Reticular white lines in a dermatofibroma.
Reticular white lines are seen in this dermatofibroma with both non-polarized (left) and polarized (right) dermatoscopy. They are brighter with polarized dermatoscopy.
white lines have also been termed “reticular depigmentation” (6) or “negative pigment network” (7) but for reasons of clarity we use only the objective language of pattern analysis.
Most white lines correspond to fibrosis or sclerosis in the dermis, some to hypergranulosis (for example the white lines seen in lichen planus), and some to a combination of both (8). Superficial fibrosis (i.e. fibrosis in the papillary dermis) and hypergranulosis are seen as white lines regardless of whether the dermatoscope uses polarized or non-polarized light. In other situations, white lines are only seen when dermatoscopes with a polarizing light source are used (9). Polarizing specific white lines are seen as two groups of parallel lines, with the groups at right angles to each other (perpendicular white lines), and correspond to fibrosis in deeper parts of the dermis.
In the short “Chaos and Clues” algorithm presented in chapter 5, any white lines seen either with polarizing or non-polarizing dermatoscopy are a clue to malignancy if they are whiter than normal skin. In pattern analysis, the interpretation of white lines depends on the context. White lines are not highly specific, being seen commonly in melanomas (7) and Spitz nevi (10, 11) (7.9), and basal cell carcinomas and dermatofibromas (12) (7.10). White lines are seen occasionally in a wide variety of other lesions. White reticular lines rule out a basal cell carcinoma with a similar high degree of certainty as pigmented reticular lines (7.11).
Angulated lines (polygons)
Angulated lines (polygons) were first described as a clue to flat melanomas on non-facial, chronic sun-damaged skin by Keir (13) (7.12). These melanomas often mimic solar lentigo and may lack other, more conventional, melanoma clues. As defined by Keir, angulated lines (polygons) form multi-sided geometrical shapes which may be completely or incompletely enclosed. In a recent study by Jaimes and Keir (14) angulated lines were found in 44 % of flat melanomas on non-facial, chronic sun-damaged skin. Facial angulated lines have been termed rhomboids (15) or zig-zag pattern (16) by others. Like angulated lines on non-facial skin, they are a clue to melanoma. Angulated lines on facial skin can also be found in pigmented solar keratosis (5).
White circles
White circles are a clue to actinic keratosis and squamous cell carcinoma (including keratoacanthomas) (2) especially on, but not limited to the face (7.13). In flat pigmented lesions on the face which have evenly distributed gray dots (differential diagnosis: melanoma in situ, lichen planus-like keratosis, and pigmented actinic keratosis) the presence of white circles helps to make the diagnosis of pigmented actinic keratosis (5) (7.14).
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Figure 7.11: White reticular lines as clue to differentiate melanoma from pigmented basal cell carcinoma.
The clinical image on the left may be interpreted as pigmented basal cell carcinoma or as melanoma. On dermatoscopy the lesion is chaotic with both polarizing specific and reticular white lines (6 o’clock). Reticular white lines rule out basal cell carcinoma. The diagnosis is melanoma (invasive, < 1 mm).
Figure 7.12: Polygons in flat melanomas on non-facial skin.
Left: This invasive melanoma is asymmetric with clues to malignancy including gray dots and eccentric structureless areas. The gray dots are arranged in lines making incompletely closed polygonal shapes. Right: This in-situ melanoma has some features suggestive of solar lentigo (curved lines, circles, scalloped border). Arrows point to some lines forming completely enclosed polygonal shapes.
7.2 Common Clichés
“Pigment network” is a melanocytic criterion
Reticular lines (pigment network) are created by melanin located on the rete ridges. Because this pigment can be in keratinocytes as well as melanocytes, no conclusion can be drawn about melanocytic status from this criterion alone (17) (7.15). While it is true that most lesions with reticular lines due to melanin pigment are melanocytic, there are frequent exceptions (see also chapter 2 for
examples of non-melanocytic lesions with reticular lines). Reticular lines also occur in seborrheic keratoses, solar lentigines and dermatofibromas. Only the pathologist can see melanocytes and the pathologist must be the arbiter of melanocytic status.
Curved lines (“fingerprint like structures”) identify a lesion as a solar lentigo/flat seborrheic keratosis
This is the most dangerous of all invalid interpretations of dermatoscopic clues because it exempts the lesion
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Figure 7.13: White circles as a clue to squamous cell carcinoma.
An unequivocal pattern of white circles is present in each of these lesions. Top left: Squamous cell carcinoma on the face (arrows point to white circles). The white circles contrast with vascular erythema surrounding them. Top right: White circles form a pattern in a squamous cell carcinoma on the ear. Middle left: Squamous cell carcinoma arising in an actinic keratosis on the nose. The white circles contrast with vascular erythema surrounding them. Yellow clods occupy the center in each of these white circles. Middle right: White circles in a keratoacanthoma. Bottom left: Squamous cell carcinoma on the ear. Bottom right: Squamous cell carcinoma on the neck.
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Figure 7.14: Dermatoscopy of two pigmented actinic keratoses on the forehead.
Left and right: Dermatoscopy of pigmented actinic keratosis on the forehead. Note that the pigment occupies the space between the white circles. The differential diagnosis includes melanoma in situ, lichen planus-like keratosis, and pigmented actinic keratosis. The clue of white circles identifies these lesions as pigmented actinic keratosis.
Figure 7.15: Reticular lines in non-melanocytic lesions.
Left: This lesion has areas of reticular lines. It was Bowen’s disease colliding with a solar lentigo and the solar lentigo produced the reticular lines. There was no melanocytic proliferation in any part of this lesion. Right: This lesion was excised (correctly) to exclude melanoma. It was reported as pigmented Bowen’s disease. The reticular lines were due to collision with a seborrheic keratosis. Both are non-melanocytic!
from further assessment to exclude melanoma. While in most cases this clue does correctly identify solar lentigines or flat seborrheic keratoses, this pattern may also be seen in melanoma. The example shown in figure 7.16 very emphatically illustrates the danger of interpreting patterns and clues without taking into account the whole context.
White dots and clods (“milia”) indicate a seborrheic keratosis
White dots and clods (milia) are produced by small intraepidermal accumulations of keratin. Although white dots and clods are most commonly found in seborrheic keratosis, they also occur in malignancies such as basal cell carcinoma and melanoma (7.17). Seborrheic keratosis should never be diagnosed on the basis of white dots and clods alone.
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Figure 7.16: Curved lines (“fingerprint like structures”) as a misleading clue to solar lentigo/flat seborrheic keratosis.
This is a lesion with curved lines (“light-brown fingerprint like structures” in the metaphoric language) that could be easily discarded as a solar lentigo/flat seborrheic keratosis. However, it is asymmetric with a clue to malignancy by virtue of gray dots. Furthermore, it lacks a well-demarcated, scalloped border. This is melanoma in situ.
Figure 7.17: White dots (“milia”) can occur in any type of lesion, not only seborrheic keratosis.
Melanoma with multiple white dots and clods (“milia”). This lesion could easily be mistaken for a seborrheic keratosis if it is not assessed in context. Clinically (left) this is a solitary lesion, whereas seborrheic keratoses usually are seen in large numbers. This anomaly should arouse suspicion and lead to careful assessment. Dermatoscopically (right) there are no yellow or orange clods, the border is poorly demarcated, and the vessels are neither looped nor centered in hypopigmented clods. Therefore there is little support for a proposed diagnosis of seborrheic keratosis, even if white dots are the standout feature of this lesion. The presence of gray dots always raises the possibility of melanoma, and this was confirmed on histopathology (invasive < 1 mm).
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Figure 7.18: Blue structureless area (“blue veil”) in a seborrheic keratosis.
Clinical view on the left, dermatoscopic view on the right. Like many seborrheic keratosis this lesion is chaotic. An unequivocal blue structureless area (“blue veil”) is present on the dermatoscopic image, a finding not uncommon in acanthotic seborrheic keratosis.
Figure 7.19: Pseudopods in a seborrheic keratosis.
Clinical view on the left, dermatoscopic view on the right. This seborrheic keratosis is chaotic, has reticular lines, and a few pseudopods at the periphery in the area indicated by the white rectangle. Whilst reticular lines are in synchrony with the diagnosis of a seborrheic keratosis, pseudopods are an unexpected finding. The scalloped and sharply demarcated border is a clue to seborrheic keratosis. White dots (“milia”) are not visible in this image taken with polarized dermatoscopy.
Blue structureless area (“blue veil”) indicates melanoma
A blue structureless area is a good clue to differentiate a melanoma from a nevus. It is not a good clue to differentiate a melanoma from a seborrheic keratosis because acanthotic seborrheic keratoses frequently show a blue structureless area (7.18). Other clues are needed in this context.
Segmental pseudopods or segmental radial lines indicate a melanoma
Although pseudopods are admittedly a very strong clue to melanoma they can be found in other lesions too. Figure 7.19 shows a seborrheic keratosis with pseudopods. Segmental radial lines can be found in basal cell carcinoma, pigmented Bowen’s disease, recurrent nevi, Reed nevi, and rarely also in Clark nevi.
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Figure 7.20: Parallel furrow pattern in an acral melanoma.
The absence of a parallel ridge pattern and the presence of a parallel furrow pattern in acral lesions does not exclude acral melanoma. This is melanoma because it is chaotic and there are clues to malignancy (eccentric structureless zone). The presence of a parallel furrows pattern does not make this a benign lesion!
A parallel furrows pattern indicates a benign acral lesion
The absence of a parallel ridge pattern and the presence of a parallel furrow pattern in acral lesions does not exclude acral melanoma (18) (7.20). The general principles of pattern analysis also apply to acral lesions. If there is chaos and a clue to melanoma then the lesion is suspicious for melanoma regardless of whether parallel lines are situated in the furrows or on the ridges.
Serpentine branched vessels indicate a basal cell carcinoma
While it is true that most basal cell carcinomas, especially when they are nodular, have serpentine branched vessels (“arborizing vessels”), it is not true that this arrangement of vessels is highly specific for basal cell carcinomas. Any tumor underneath the superficial
vascular plexus may show serpentine branched vessels in dermatoscopy including other neoplasms (19), cysts (20), deposits, and inflammatory lesions (21) (7.21).
Malignant neoplasms are chaotic
Although most pigmented cutaneous malignant neoplasms are chaotic by dermatoscopy there are important exceptions: Small melanomas, nodular melanomas, and flat facial and acral melanomas are often symmetrical (7.22). Whilst in large and flat lesions chaos takes precedence over clues, clues are more important than chaos in small (5 mm and less) and nodular lesions. Very rarely chaos may be absent even in large and flat melanomas (7.23). In these cases, information beyond dermatoscopy like the clinical context (“ugly duckling”) or the history given by the patient (“changing lesion”) may draw the attention of the examiner to the lesion.
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Figure 7.21: Benign and malignant neoplasms and cysts with serpentine branched vessels on dermatoscopy.
Serpentine branched vessels can be found in any tumor that is situated underneath the superficial vascular plexus, not only in basal cell carcinomas. Four examples are trichoepithelioma (top left), eccrine hidrocystoma (top right), pilar sheath acanthoma (bottom left), Merkel cell carcinoma (bottom right). Images courtesy of Nisa Akay, Jean-Yves Gourhant, Iris Zalaudek and Giuseppe Argenziano).