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Common clinical scenarios: Side-by-side comparisons of similar-appearing lesions that are benign or malignant


Introduction

When you examine a skin lesion with dermoscopy, it might be obviously benign or malignant. There is also a gray zone of equivocal lesions. Gray-zone lesions will commonly be encountered by the novice dermoscopist. To help deal with this common situation, we offer a few suggestions. Learn the basics, practice the technique as often as possible, and develop a dermoscopic differential diagnosis.

You have to be able to think things through logically, weighing the pros and cons for each criterion or pattern that you see. Coming up with a tentative dermoscopic diagnosis, or in many cases, a dermoscopic differential diagnosis, is the end of the process.

For example, are the round to oval yellow dots and globules you see the milia-like cysts of a seborrheic keratosis or the follicular ostia of a melanocytic lesion? What a difference that distinction could make. You could be dealing with a seborrheic keratosis or a lentigo maligna. Are those the brown dots and globules of a melanocytic lesion, or the pigmented follicular openings of a seborrheic keratosis? You notice that the lesion has some blood vessels. Are they the thickened branched vessels of a basal cell carcinoma or the irregular linear vessels that can be found in melanomas?

We regret to inform you that you will encounter difficult lesions—lesions that even the most experienced dermoscopist will not feel confident about. That is the state of the art as it exists today. There are infinite variations of criteria, patterns, and lesions. The scenarios in this final chapter demonstrate the dermoscopic thought process we employ. Focus your attention, use what you have learned in the first two chapters of the book, and you will find that you will learn and grow with each case. Do not be intimidated by what you see. We guarantee that you can master this technique. You will develop your own style of dermoscopic analysis and find that dermoscopy will become an essential part of your practice. You will not be able to practice without it!

Pediatric scenario

General principles

  • Melanoma in childhood is exceedingly rare, and the great majority of melanocytic skin lesions in prepubertal children are benign and do not require any special attention. The dermoscopic criteria of childhood nevi are the same as in other age groups, but in most cases, childhood nevi reveal a globular pattern.

  • The most problematic skin tumors in the pediatric patient are large to giant congenital melanocytic nevi and atypical Spitz tumors.

  • Large to giant congenital nevi represent the most important risk factors for melanoma in prepubertal children, although the risk is still low (<1%). Because melanoma associated with large to giant congenital melanocytic nevi often develops deep in the dermis or in the central nervous system, dermoscopy is of limited benefit in the early diagnosis of melanoma.

  • The risk for melanoma in small to medium congenital melanocytic nevi is not established, but they should be kept under regular surveillance. Biopsy is indicated in the case of significant atypical structural changes.

  • There are no definitive guidelines about the management of Spitz nevi, and there are controversies about whether to follow up or excise these nevi. However, flat pigmented Spitz nevi (commonly also called Reed nevi) with a stereotypical dermoscopic starburst pattern, appearing below the age of puberty, can be managed conservatively and can be regularly followed up as there is a well-documented tendency of involution.

  • Atypical Spitz tumors and rare childhood melanomas commonly present as rapidly growing, pigmented or nonpigmented nodules. Immediate excision of any lesion showing these clinical characteristics is indicated.

    Fig. 261, Congenital nevus.

    Fig. 262, Melanoma in situ arising in a small congenital nevus.

    Fig. 263, Pigmented Spitz nevus (Reed nevus).

    Fig. 264, Flat nonpigmented Spitz nevus.

    Fig. 265, Atypical nonpigmented Spitz tumor.

    Fig. 266, Melanoma.

    Fig. 267, Common nevi.

Black lesions

General principles

  • Clinically, black color is not always ominous.

  • Black color with dermoscopy is also not always ominous.

  • The differential diagnosis of a single black macule or papule could be melanocytic or nonmelanocytic, benign or malignant.

  • What should be done on finding a black lesion? Check it out with dermoscopy before making another move.

    Fig. 268, What is your clinical diagnosis?

    Fig. 269, What is your clinical diagnosis?

    Fig. 270, Melanoma.

    Fig. 271, Melanoma.

    Fig. 272, Seborrheic keratosis.

    Fig. 273, Spitz nevus.

Inkspot lentigo

General principles

  • Clinically and dermoscopically inkspot (or reticular) lentigines have a very characteristic appearance.

  • Typically, an inkspot lentigo is black and sharply demarcated with a bizarre-looking pigment network filling the lesion. There is an absence of other criteria.

  • Individuals with inkspot lentigines commonly have fair skin, light hair, and light eyes and are at risk of developing melanoma. Do not forget to do a comprehensive skin examination to look for high-risk pigmented skin lesions.

  • Inkspot lentigines are usually located on the upper trunk and extremities and are surrounded by regular or large sunburn freckles.

  • On seeing an “inkspot lentigo,” try not to miss seeing the presence of any melanoma-specific criteria.

  • If in doubt, cut or shave it out.

    Fig. 274, Inkspot lentigo.

    Fig. 275, Inkspot lentigo.

    Fig. 276, Inkspot lentigo.

    Fig. 277, Inkspot lentigo.

    Fig. 278, Clark (dysplastic) nevus.

    Fig. 279, Melanoma.

Blue lesions

General principles

  • Blue color can be seen in benign and malignant lesions. They are not all blue nevi.

  • Blue color indicates that melanin is deep in the dermis.

  • It is imperative to develop a complete differential diagnosis for blue lesions.

  • If you see a lesion with blue color but it also has other criteria, it should be evaluated like any other lesion.

  • Blue lesions can be tricky. If in doubt, do not hesitate—cut it out.

    Fig. 280, Nodular melanoma on the face.

    Fig. 281, Basal cell carcinoma.

    Fig. 282, Melanoma.

    Fig. 283, Basal cell carcinoma.

    Fig. 284, Melanoma metastasis.

    Fig. 285, Blue nevus.

Reticular lesions

General principles

  • Take a bird’s-eye (global) view of the entire lesion to get a first impression.

  • Reticular pattern = significant areas with pigment network.

  • Is the pigment network typical or atypical?

  • What other criteria are there to make the dermoscopic diagnosis?

    Fig. 286, Melanoma in situ.

    Fig. 287, Clark (dysplastic) nevus.

    Fig. 288, Clark (dysplastic) nevus.

    Fig. 289, Melanoma.

    Fig. 290, Melanoma.

    Fig. 291, Melanoma.

Spitzoid lesions

General principles

  • Spitzoid means similar in appearance to a starburst pattern.

  • Spitzoid differential diagnosis includes Clark (dysplastic) nevus, Spitz nevus, and melanoma.

  • Spitzoid morphology comprises a light-dark or blue central area and dots and globules or streaks at the periphery.

  • Symmetrical Spitzoid pattern = benign lesion.

  • Asymmetrical Spitzoid pattern = rule out melanoma.

  • The stereotypical starburst pattern is seen more frequently than the globular pattern, which is more common than the nonspecific Spitzoid pattern.

Caution

Deaths have occurred secondary to metastatic “Spitz” nevi that were in reality melanomas. Excise the vast majority of Spitzoid lesions. It is better to be safe than sorry.

Fig. 292, Spitz nevus.

Fig. 293, Melanoma.

Fig. 294, Spitz nevus.

Fig. 295, Melanoma.

Fig. 296, Spitz nevus.

Fig. 297, Melanoma.

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