An important clue to the diagnosis of a potential melanoma that neither the ABCDE criteria nor the Glasgow checklist captures is a sign called the “ugly duckling syndrome.” When one lesion clearly does not look like the other lesions on a patient’s skin, there should be concern for malignancy, and a biopsy may be warranted.
Areas that should receive special consideration include the hands and feet, nails, and genitals. Ethnic groups with more pigment in their skin naturally tend to develop melanomas at a lower rate. When melanomas do develop, they often occur on the palms of the hands and soles of the feet, or in the nails. Because the diagnosis is frequently delayed, melanoma in a person of color carries a much worse prognosis. If you see a pigmented lesion in a nail or nail bed, on the palm of a hand, or on the sole of a foot of a patient of any ethnic background, it is suggested that the input of a dermatology provider be obtained.
Dermoscopy can help a clinician view pigmented lesions and more readily differentiate cancers from benign growths. Benign growths to be considered in the differential diagnosis of a melanoma include benign nevi, lentigines, seborrheic keratosis, and vascular lesions such as venous lakes and purpura. A dermatoscope is a handheld microscope that also illuminates lesions with direct and polarized light. Dermatoscopes can cost between $250 and $3,000. Multiple conferences and textbooks are available that can help a clinician learn how to use a dermatoscope properly in the decision-making process. As a dermatology provider, I personally find this tool absolutely invaluable.
If a clinician is unsure about a lesion or has looked at a lesion repeatedly while debating what to do, the patient should be referred to a dermatology practice (Figure 2). Skin biopsy is a relatively low-risk procedure, and in the case of melanoma, the benefit of early diagnosis far outweighs the risk of skin biopsy. Melanomas are aggressive and deadly.
Figure 2. Subtle melanoma on the chin.
To highlight this fact, it is important to note that when a patient has a melanoma with a thickness of 0.75 mm or more, sentinel lymph node biopsy (SLNB) is recommended. SLNB is also advised for patients who have melanomas with a thickness of less than 0.75 mm if there is a high risk for metastasis.6 Risk factors for metastasis include ulceration of the primary tumor, a mitotic rate of 1/mm2 or higher, and lymphovascular invasion.6 Any patient with a melanoma and a clinically palpable lymph node must undergo fine-needle biopsy of the lymph node. Patients who have stage I melanoma with no metastasis have a 5-year survival rate between 92% and 97%.7 In contrast, patients who have stage IV melanoma have a 5-year survival rate between 15% and 20%.7
Basal cell carcinoma
Basal cell carcinoma (BCC) is the most common skin cancer. These skin cancers grow slowly and can destroy local tissue. In rare instances, BCC can even invade local bone structure. If untreated, BCC can bleed and can become sore and ulcerated, negatively impacting daily life. The typical BCC is a pearly papule with a glossy appearance (Figure 3). Small telangiectases may be visible within the lesion and are easier to visualize with a dermatoscope.
Figure 3. A classic lesion of basal cell carcinoma.
A common chief complaint of patients with BCC is “a pimple that will not heal” (Figure 4). A pimple (especially when treated with an over-the-counter topical agent such as benzoyl peroxide or a prescribed topical antibiotic) should not last longer than 3 weeks.
Figure 4. Patients may refer to some subtle basal cell carcinomas, such as these, as pimples that will not heal.