Surface microscopy is a noninvasive diagnostic technique that can aid in (1) early diagnosis of some melanomas, and (2) evaluation and management of other pigmented and non-pigmented skin lesions. Dermatoscopy is the technical name for "surface microscopy", a technique for examining the surface of the skin with special microscopic methods. The technique requires special expertise. It is a technique used when the dermatologist needs additional information in confirming a diagnosis; most melanomas are readily diagnosed by experienced dermatologists by visual examination. Dermatoscopy may complement other diagnostic techniques and may help to determine which lesions require a biopsy or removal.

Some pigmented lesions look so much like melanoma that a dermatologist will recommend immediate excisional or incisional biopsy—a procedure that is diagnostic and often curative if a melanoma is removed when confined to upper layers of the skin (Click on Thickness for information about the relationship between tumor thickness and survival).

In some instances the dermatologist may want more information before proceeding to a biopsy, or before deciding that a biopsy is warranted. For example:

• The pattern of pigmentation in the lesion is not clearly one of malignancy.
• The dermatologist suspects that the pigmented margin of the lesion is wider than the margin visible to the unaided eye; in some instances, a lesion may entirely lack a pigment network.
• In a patient with dysplastic nevi (a risk factor or potential precursor for melanoma), the dermatologist may want to assess the lesions for changes over time using photographic surveillance. New lesions and significantly changed lesions are often evaluated for biopsy.

In cases such as these, the dermatologist may recommend examination of the suspect lesion(s) by the technique of surface microscopy.

It is important to note that surface microscopy complements other diagnostic techniques and may be used to determine which skin lesions require biopsy. Biopsy and pathological microscopic examination is the only diagnostic method that can positively exclude or confirm a diagnosis of melanoma, but not all lesions require biopsy.

In a number of studies, surface microscopy performed by an experienced dermatologist has been shown to be useful in (1) improving the accuracy of pre-biopsy diagnosis of melanoma, (2) detecting early melanoma, and (3) aiding the diagnosis of other benign and malignant pigmented lesions.

Surface microscopic examination reveals the pigment network and vascular structures of pigmented and nonpigmented lesions. These structures are usually invisible to the unaided eye. These photos show lesions viewed without, and then with, the aid of dermatoscopy:

A lesion resembling seborrheic keratosis. See next photo.

Dermatoscopy with mineral oil reveals subtle, branched streaks at the periphery of the lesion that show the lesion to be melanocytic. The white areas within the lesion suggest malignancy. Melanoma was confirmed by biopsy.

A lesion that is suspicious for melanoma. See next photo.

Surface microscopy using mineral oil reveals a pigmented network and branched streaks at the periphery, suggesting the lesion to be melanocytic. Slate-gray areas and whitish areas plus variegated color suggest malignancy. Biopsy confirmed the lesion as a nodular melanoma.

A pigmented lesion suspicious for melanoma. See next photo.

Surface microscopy using mineral oil shows aggregated globules of irregular size, suggesting malignancy. Biopsy confirmed the lesion as a superficial spreading melanoma.

(Photos used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides and the Sulzberger Institute for Dermatologic Education)

A pigment network visualized in a lesion usually indicates that the lesion is melanocytic (containing melanocytes, pigment-producing cells). The structure of the network provides important information regarding the degree of abnormalities of the lesion. The extent of the network indicates the actual margin of the lesion—important to know if the lesion is going to be surgically removed with all potentially malignant adjacent tissue.

Surface microscopic examination provides information for making decisions about (1) additional diagnostic measures that might be needed, and/or (2) treatment. Decisions are always individualized based on considerations such as other risk factors for melanoma and clinical history for a given lesion.

References

Langley RGB et al. Clinical characteristics. In: Balch CM et al (Eds). Cutaneous Melanoma, 3^rd ed. St. Louis: Quality Medical Publishers, Inc.; 1998:82-101.