Applied Evidence

Diagnosing skin malignancy: Assessment of predictive clinical criteria and risk factors

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References

The most common nodular type is a smooth, skin-colored, indurated, dome-shaped papule with a rolled edge. Other attributes include a pearly appearance, overlying telangiectatic vessels, and a history of bleeding with minor trauma.7,11

Superficial basal cell carcinoma is similar to dermatitis but more often has distinct borders and a bright pink appearance.11 If in doubt about the diagnosis, obtain a tissue sample for pathology.

Squamous cell carcinoma

Squamous cell carcinoma most often is a small, firm, hyperkaratotic nodule sitting atop an inflamed base. It may also be skin-colored and smooth. The history can include itching, pain, and nonhealing after minor trauma.7,11,12 As with basal cell carcinoma, diagnosis is made by tissue pathology.

Malignant melanoma

Malignant melanoma usually appears as a changing or unusual mole with haphazard color variegation, including combinations of brown, black, blue, gray, white, and (rarely) pink. Most melanomas are larger than 5 mm in diameter at time of diagnosis.13

There are 4 main types of malignant melanoma:

  • Superficial spreading melanoma accounts for 50% of cases and occurs more frequently in younger adults.
  • Nodular melanoma also occurs in younger adults, representing 20% to 25% of cases.
  • Lentigo maligna melanoma occurs in older adults and accounts for only 15% of cases.
  • Acral or acral-lentiginous melanomas are the least common form (10% of cases). They appear on the palms, soles, and around the first toenail.14

Risk factors for skin malignancies

Factors conferring the highest relative risk for malignant melanoma include:13

  • atypical nevus syndrome with a personal and family history of melanoma
  • history of a changing mole
  • atypical nevus syndrome with just a family history of melanoma
  • age greater than or equal to 15 years
  • history of dysplastic moles.

Table 1 provides a list of risk factors that should prompt an annual skin survey (LOE: 5).

For nonmelanoma skin cancers, the strongest risk factors ( Table 2) include Caucasian race; age 55 to 75 years; and male sex.2 There is good evidence that a history of nonmelanoma skin cancer confers a 10-fold risk for recurrence (LOE: 2a).15 A distinct risk factor for squamous cell carcinoma is immunosuppression.2 Table 2 also provides a complete list of risk factors for nonmelanoma skin cancer.

Precursor lesions for nonmelanoma skin cancers include Bowen’s disease and erythroplasia of Queyrat (forms of squamous cell carcinoma in situ that will progress if left untreated). Actinic keratoses are common precursor lesions, but their overall annual rate of malignant transformation is only 1 in 400. In the case of SCC, up to 60% of cancers develop from an existing actinic keratosis.2

TABLE 1
Risk factors for malignant melanoma
13

Risk factors that should prompt an annual skin surveyRR (LOE)*
Atypical nevus syndrome with personal and family history of melanoma500 (1b)
Changing mole>400 (4)
Atypical nevus syndrome with family history of melanoma148 (1b)
Age ≥ 1588 (2c)
Dysplastic moles7–70 (3b)
History of melanoma before age 4023 (2b)
Large congenital nevus (≥15 cm)17 (2b)
Caucasian race12 (2b)
Lentigo maligna10 (2c)
Atypical nevi7–27 (3b)
Regular use of tanning bed before age 307.7 (3b)
Multiple nevi5–12 (3b)
Personal history of melanoma5–9 (2b)
Immunosupression4–8 (2b)
Family history (first degree) of melanoma3–8 (3b)
Nonmelanoma skin cancer3–5 (3b)
Sun sensitivity or tendency to burn2–3 (3b)
*See page 239 for a description of levels of evidence
†(95% CI, 40–379)
‡(95% CI, 1–63.6)
RR, relative risk (compared with person without risk factors);
LOE, level of evidence;
CI, confidence interval

TABLE 2
Risk factors for nonmelanoma skin cancer

Significant risk factorsRRLOE*
Caucasian race702c
Immunosuppression5–202c
Previous nonmelanoma skin cancer102a
Age 55–754–82c
Male sex22c
Genetic risk factors associated with nonmelonoma skin cancer 3
  • blue eyes
  • sunburn easily
  • Celtic ancestry (Scottish, Irish, Welsh)
Chemical exposure risk factors associated with nonmelonoma skin cancer (particularly squamous cell carcinoma) 3
  • coal tar
  • tobacco
Environmental factors and medical conditions associated with nonmelonoma skin cancer (particularly squamous cell carcinoma) 3
  • ionizing radiation
  • genetic syndromes (xeroderma pigmentosum, albinism, epidermodysplasia verruciformis, basal cell nevus syndrome)
  • any primary inflammatory skin disorder
*See page 239 for a description of levels of evidence
RR, relative risk (compared with person without risk factors); LOE, level of evidence

Clinical prediction rules for skin malignancies

Malignant melanoma

ABCDE criteria. A useful clinical prediction rule for malignant melanoma is the American Cancer Society’s “ABCDE criteria” (Table 3). This rule was validated in 4 dermatology clinics, studying a total of 1118 lesions, although the studies were not homogenous (strength of recommendation [SOR]: A).16-19 Results of the study are summarized in Table 4. The test is normally considered positive if one or more of the criteria are met; however, as more criteria are met, specificity increases while sensitivity decreases.17-19

For lesions lacking any of the ABCDE criteria, 99.8% are something other than melanoma (using a prevalence of 1% found in the US population) (SOR: A). Use caution, however, as this rule will miss amelanotic melanomas, as well as smaller melanomas that are changing in size or have other features suggestive of malignant melanoma.

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