Age May Affect Specificity of Dermoscopy for Melanoma

Laurie Barclay, MD

June 17, 2011

June 17, 2011 — Age and other factors may affect the specificity of dermoscopy for diagnosis of melanoma, according to the results of 2 studies reported in the June issue of the Archives of Dermatology.

"Sequential digital dermoscopic imaging (SDDI) allows the detection of morphologic change of melanocytic lesions over time that permits the detection of early melanoma without specific dermoscopic features of malignant neoplasms (so-called featureless melanoma)," write Scott W. Menzies, MB, BS, PhD, from Sydney Medical School, University of Sydney and Sydney Melanoma Diagnostic Centre, Royal Prince Alfred Hospital in Camperdown, New South Wales, Australia, and colleagues. "Long-term SDDI is performed during standard surveillance periods (i.e., 6-12 months) in patients with nevi that are not suspicious of melanoma. Long-term SDDI is usually performed in patients with multiple atypical nevi."

Study: Menzies and Colleagues

The goal of the retrospective cohort study by Menzies and colleagues was to examine whether specific demographic variables are associated with poorer specificity for the diagnosis of melanoma in nevi evaluated with short-term SDDI. From April 1, 1998, through May 31, 2007, a total of 1765 patients with a total of 2497 benign melanocytic lesions underwent short-term SDDI at the study authors' tertiary referral institution during a 2.5- to 4.5-month interval. Mean age of patients was 40 ± 14 years (range, 1 - 86 years); 42.3% were men. The primary study endpoint was the proportion of changed nevi, analyzed by age, sex, lesion diameter, and anatomic location.

Age group was the only factor significantly associated with nevus change (= .002). With use of the middle-aged group (36 - 50 years old) as a reference standard, the odds of change were significantly greater in the child and adolescent group (0 - 18 years old: odds ratio [OR], 2.60; 95% confidence interval [CI], 1.30 - 5.22), young adult group (19 - 35 years old: OR, 1.50; 95% CI, 1.04 - 2.17), and elderly group (> 65 years old: OR, 2.04; 95% CI, 1.04 - 3.99).

Histologic subtype and age group were significantly associated (P = .01) within the changed benign lesions, in that the proportion of changed lesions of the banal nevi type decreased and the proportion of the dysplastic nevi type increased with age. The dysplastic nevi type of changed lesions comprised 75.9% of changed lesions in the elderly group vs 35.7% in the youngest group.

"A poorer specificity is observed for the diagnosis of melanoma for nevi undergoing short-term sequential digital dermoscopic imaging in children and adolescents (75.7%) and elderly patients (77.9%) compared with other patients (84.6%)," the study authors write.

Limitations of this study include retrospective design, selection bias, and uncertainty of the criterion standard histologic definition of early in situ melanoma.

Is Biopsy Always Necessary?

An accompanying "practice gaps" commentary by Bernard Cohen, MD, from Johns Hopkins University School of Medicine in Baltimore, Maryland, notes that it may not always be necessary to perform a biopsy on changing moles in children and adolescents, based on the findings of this study and others.

"Closing the practice gap requires heightened awareness of the normal evolution of acquired nevi in children and adolescents, recognition of signature nevi as a reassuring factor, and acceptance of regular monitoring of 'moley' children and adolescents and those with multiple atypical nevi rather than routine biopsy of those lesions as the standard of care," Dr. Cohen writes.

"Mole changes are normal in children; the ABCD criteria (asymmetry, border, color, and diameter) for moles and melanomas may not be helpful in identifying melanomas in patients younger than 18 years. The role of pediatric dermatologists and those involved in studying pigmented nevi in children and adolescents is to develop useful criteria for recognizing high-risk lesions and to educate the general dermatologist regarding his or her role in monitoring patients who have them and in counseling their families accordingly."

Study: Zalaudek and Colleagues

The goal of the second study, by Iris Zalaudek, MD, from the Department of Dermatology, Medical University of Graz in Graz, Austria, and colleagues, was to subclassify acquired nevi based on dermoscopic pattern. Between October 1, 2008, and May 31, 2009, a total of 480 patients older than 2 years undergoing total skin examination were consecutively enrolled from pigmented lesion clinics in referral academic medical centers.

Patients were classified into 8 groups based on age, and all nevi (n = 5481) on the torso were described according to location and dermoscopic pattern (globular, reticular, mixed [reticular globular] pattern with peripheral or central globules, or unspecified). The primary study endpoint was the frequency of dermoscopic nevus subtypes as a function of patient age and nevus location.

Except for unspecified pattern nevi, the number of all nevus subgroups significantly increased before the fourth decade of life and decreased thereafter. In children and adolescents, globular nevi were most often observed on the upper trunk, and these decreased consistently with increasing age thereafter.

The most prevalent nevus subgroup on the upper and middle back was the reticular pattern, which was also the most common nevus pattern after the second decade of life. Central globular nevi were infrequent but had an age-dependent trend similar to that of reticular nevi. After the third decade of life, peripheral globular pattern nevi decreased rapidly and were no longer seen in patients older than 60 years. All age groups had a similar prevalence of unspecified pattern nevi.

"Age, dermoscopic pattern, and location of nevi should be jointly considered when evaluating melanocytic lesions," the study authors write.

Limitations of this study include interobserver variability in reading dermoscopic patterns, cross-sectional design, lack of evaluation of prevailing color and pigment distribution of nevi, exclusion of obvious congenital nevi based on history, and relatively low nevus count in some of the participants.

"In conclusion, our study demonstrates significant age- and anatomic site–related differences in the prevalence of various nevus dermoscopic subgroups," the study authors conclude. "These findings should be integrated into the management of nevi in patients. In particular, any melanocytic lesion showing peripheral globules or signs of growth in a patient older than 50 years should be considered highly unusual."

Critical Role of Nevi Growth Rate

In an accompanying editorial, James M. Grichnik, MD, PhD, from the Miller School of Medicine, University of Miami in Miami, Florida, notes that both studies indicate that different types of benign nevi have discrete growth curves.

"Although lack of growth plays a critical role in the discrimination of benign nevi from malignant lesions, 99.2% of stable lesions are benign, and growth by itself does not necessarily indicate malignancy," Dr. Grichnik writes. "An improved understanding of normal nevus growth processes will allow us to improve patient care through accurate identification of melanomas and reduction of unnecessary biopsies of benign lesions."

The study by Zalaudek's and colleagues was supported by the Elise Richter Program of the Austrian Science Fund. The authors of both studies have disclosed no relevant financial relationships. Dr. Grichnik is a founder of and major shareholder in DigitalDerm Inc (MoleMap CD, a full-body photography service) and has received grants and consulted for MELA Sciences Inc (regarding MelaFind, a melanoma detection device) and Spectral Image Inc (Dermatologic Diagnostics). He has also consulted for Genentech Inc and serves on the editorial board of the Archives of Dermatology.

Arch Dermatol. 2011;147:655-659, 659-660, 663-670, 731-732.

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