Avoiding Delayed Diagnosis of Malignant Melanoma

Thomas Jarrad Matzke; Andrew K. Bean; Tanya Ackerman

Disclosures

Journal for Nurse Practitioners. 2009;5(1):42-46. 

In This Article

Clinical Aspects of Melanoma

Early diagnosis begins with a thorough clinical evaluation, along with patient education emphasizing the importance of routine complete self-exams. Performing a full-body skin exam is essential, as melanoma can occur anywhere on the skin. It may be tempting to avoid examining the lower body, as it may be inconvenient for the provider or patient. However, lower extremities in particular are one of the most common sites of melanoma, especially in women. In our practice, a significant proportion of melanomas was not noticed by the patient prior to their visit. Informing patients of this may make them more agreeable to full exams.

Patients should be educated that, although melanoma is most common in sites exposed to large doses of ultraviolet exposure intermittently, they do occur in areas not exposed to ultraviolet radiation. These sites are less common, and tend to be diagnosed when the disease is more advanced, as patients may falsely assume that lesions can't be skin cancer in areas not exposed to the sun.

Clinically, melanoma usually displays a lack of uniformity, and patients will often report that the lesion is changing. The ABCDs will identify most melanomas (Figure 1). In addition, E has been recently added, which stands for Evolution, signifying the importance of change. Dysplastic nevi share many of the same features and can be difficult to distinguish clinically; therefore, obtaining histology is often necessary (Figure 2). Photographs can be helpful for patients with many nevi or to follow mildly suspicious lesions. This allows increased accuracy and objectivity when watching for change. We prefer to have patients take the photographs themselves, and they should be encouraged to use them during self-exams. This also facilitates the patients becoming active in their care.

Lesion exhibiting 3 colors: tan, black, and red, and notched border and history of change. Diagnosis was malignant melanoma in situ when the lesion was removed. Three years earlier, partial biopsy was interpreted as inflamed lentigo.

Malignant melanoma and dysplastic nevi can be difficult to distinguish clinically, both displaying nonuniformity. A and C were dysplastic nevi, and B and D were melanoma in situ. Cancer of the Skin, 2005. Reprinted with permission of Elsevier.

Approximately 6% of melanomas do not display the typical features, often resulting in delayed diagnosis.[2] Melanoma may lack the typical dark color, mimic common benign lesions, or be generally nondescript, having only subtle or no areas of pigmentation (Figure 3, Figure 4, Figure 5, Figure 6). Although melanoma is not usually diagnosed until it is greater than 6 mm, a small but significant proportion of diagnosed melanomas are smaller than this.[1] Because melanoma begins as a single malignant melanocytic cell, small lesions should not be ruled out based on size. New and changing lesions should be evaluated carefully and, if not removed, they need to be followed closely.

Amelanotic melanoma on the ear of a middle age man. Usually, there is faint pigmentation at the edge of the lesion on close inspection; however, they can be completely amelanotic, as is the case in this lesion. Always beware of changing lesions that are not completely characteristic of benign lesions. Cancer of the Skin, 2005. Reprinted with permission of Elsevier.

Amelanotic melanoma on the leg. Mostly reddish slightly elevated plaque, but does have a subtle pigment network in part of the lesion. Patient had noticed that it was new and changing and was suspicious, as she had a previous melanoma on the opposite leg. Cancer of the Skin, 2005. Reprinted with permission of Elsevier.

Malignant melanoma, breslow depth 0.8 mm, on the shoulder. This lesion was greater than 2 cm and developed an eczematous reaction, resulting in the erythema and scale, which involved and surrounded the lesion. Given the large size of this lesion, this is an exception of when a large sample biopsy is acceptable. The corollary is that one must stay suspicious if a benign diagnosis is rendered.

Malignant melanoma with regression exhibited by white and grey central coloration. Peripheral pigmentation is still present. Cancer of the Skin, 2005. Reprinted with permission of Elsevier.

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