Flat/Pink-Clear/Red
Step 1: Is the lesion is flat or raised? Flat
Step 2: What color is the lesion on clinical assessment? Pink/Clear
Step 3: What is the dermoscopic color? Red
Step 4: Is further elucidation needed to decide whether to biopsy or not? Yes
Is this a malignant or benign pattern?
Take a look at the color wheel in Figure 4.1.
Using the color wheel in Figure 4.1, we cross-reference the clinical and dermoscopic lists:
Malignancies: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), +/- porokeratosis
Benign: benign porokeratosis, clear cell acanthoma, or lichen planus-like keratosis/irritated seborrheic keratosis, +/- porokeratosis
Keep in mind that we are only considering flat lesions here, so dermatofibroma and intradermal nevi are not considered!
Benign Lesions
Porokeratosis
Pearls
Flat/Pink-Clear/Red
A clinically and dermoscopically evident double rim of scale represents the cornea lamella on pathology.
While these lesions are considered benign, and do not change over time, squamous cell skin cancer can grow within these lesions; therefore, the lesions are usually treated/biopsied.
Step 4 Pattern: On dermoscopy, a double rim of scale is visible, and if the lesion is not too thick, you can see a vascular pattern.
Diffuse dotted vessels
Bottom line: Benign, biopsy not necessary.
Examples
Figure 4.2 shows a clinically flat, pink or skin-colored lesion with a dermoscopic red, vascular pattern. A double-rimmed scale is also evident. Diagnosis: Porokeratosis.
Bottom line: Benign, biopsy not necessary.
Figure 4.3 shows a clinically flat, pink or skin-colored lesion with a dermoscopic red, vascular pattern. A double-rimmed scale is also evident. The diffuse dotted vascular pattern is shown here. Diagnosis: Porokeratosis.
Bottom line: Benign, biopsy not necessary.
Figure 4.4 shows a clinically flat, pink/skin-colored lesion with a less obvious red/vascular pattern on dermoscopy. The double-rimmed scale is evident. Diagnosis: Porokeratosis.
Bottom line: Benign, biopsy not necessary.
Lichen Planus-Like Keratosis or Benign Lichenoid
Pearls
Flat/Pink-Clear/Red
These lesions are often difficult to differentiate from malignant melanoma and nonmelanoma cancers.
Step 4 Pattern: We will use the patterns described in Chapter 1 to look for benign features: sharp borders, moth-eaten borders, fingerprint patterns, milia-like cysts, comedo-like openings, and ridges.
These lesions are either solar lentigines undergoing regression or an inflammatory reaction or a seborrheic keratosis undergoing regression or inflammatory reaction.
The inflammatory nature of these lesions leads to a nonspecific vascular pattern.
Bottom line: Benign, biopsy not necessary.
Examples
Figure 4.5 shows a clinically flat, pink lesion, with a faint red vascular dermoscopic pattern. The nonspecific inflammatory vascular pattern causes a crystalline, scar-like center and a faint peripheral pseudonetwork pattern. Diagnosis: Lichen planus-like keratosis.
Bottom line: Benign, biopsy not necessary.
Figure 4.6 shows clinically flat, pink lesions with nonspecific inflammation causing faint red vascular dermoscopic pattern. Diagnosis: Lichen planus-like keratosis.
Bottom line: Benign, biopsy not necessary.
FIGURE 4.7 Clinically flat lesions that are pink or skin-colored with a vascular dermoscopic pattern. A,B: Clinical examples of clear cell acanthoma. C: A dermoscopic image of this lesion, showing a serpiginous, string-of-pearls-like pattern of vessels.
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