Chapter 31: Dermoscopy

SYNONYMS

• Dermatoscopy

• Skin surface microscopy

• Epiluminescence microscopy (ELM)

• Digital dermoscopy/digital ELM

• Auflichtmikroscopie (German)

• Dermoscopia/dermatoscopia (Spanish)

• Dermoscopy and dermatoscopy are used interchangeably by experienced dermoscopists and in the literature

DEFINITION

• Dermoscopy is an in vivo, noninvasive technique in which oil or fluid (e.g., mineral oil, gels, alcohol, and water) is placed on the lesion

  • Fluid eliminates reflection of light from the surface of the skin allowing visualization of color and structure in the epidermis, dermoepidermal junction, and papillary dermis

  • The color and structure visualized cannot be seen with the naked eye or with typical magnification that clinicians use

  • Polarizing light and digital instrumentation do not require fluid

• When using polarized light dermoscopy

  • Light from a polarized light source penetrates the stratum corneum with less scatter

  • A second polarizer screens out scattered surface light resulting in the physician seeing primarily light from the deeper structures

  • This removes the need for contact with the skin and the need for immersion fluids, resulting in faster examination times

• There is noncontact and contact polarized dermoscopy

  • Gels can be used with contact polarized dermoscopy to enhance the appearance of vessels or eliminate the negative effects of dry skin

• There is contact nonpolarized dermoscopy

  • Some criteria can be better visualized with polarized dermoscopy such as small vessels, blue-white color, etc.

  • Some criteria can be better visualized with nonpolarized contact dermoscopy such as milia-like cysts seen in seborrheic keratosis and melanocytic lesions

  • Crystalline (a.k.a. shiny white structures) can only be seen with polarized dermoscopy

  • All the criteria needed to make a dermoscopic diagnosis can be made using any form of the technique

BENEFITS OF DERMOSCOPY

• Helps to differentiate melanocytic from nonmelanocytic skin lesions

• Helps to differentiate benign from malignant skin lesions

• With dermoscopy, the sensitivity to diagnose melanoma is 85% and better compared to 65 to 80% when the technique is not used

• Increases the diagnosis of early melanoma

  • Increases the diagnosis of amelanotic and hypomelanotic melanoma

• Increases the diagnosis of melanoma incognito (false negative melanoma)

• Increases the diagnosis of inflammatory lesions (i.e., lichen planus, psoriasis, seborrheic dermatitis)

• Increases the diagnosis of infestations (i.e., scabies, head and crab lice)

• Increases the diagnosis of hair shaft pathology (i.e., monilethrix, trichorrhexis invaginata)

• Helps to avoid unnecessary surgery

• Helps to plan surgery

• Helps to work better with a pathologist (asymmetrical high-risk criteria, dermoscopic–pathologic correlation)

• Patient reassurance

• Allows for follow-up of patients with multiple nevi digitally to find changes over time

DERMOSCOPIC DIGITAL MONITORING

• There are pigmented skin lesions that are not high risk enough to warrant immediate histopathologic diagnosis, yet not so banal that there is no concern at all

• There are melanomas that do not appear to be high risk clinically or with dermoscopy

• They are only diagnosed after monitoring for dermoscopic changes over time when comparing baseline with subsequent digital images

• Short-term monitoring is performed every 3 ...