Invasive Melanomas May Appear as Small Lesions

Invasive melanomas may be detected as small-diameter lesions and are potentially metastatic, according to study findings published in Journal of the American Academy of Dermatology.

Researchers conducted a retrospective study using patient data from the European Association of Dermato-Oncology database. They evaluated invasive melanomas of the nodular melanoma or superficial spreading melanoma subtype that had a maximum diameter of 6 mm on histologic sections diagnosed between 2006 and 2015.

Follow-up for small-diameter melanomas was conducted until 2022. Multivariate logistic regression and Kaplan-Meier estimator were used to analyze metastasis.

A total of 537 invasive melanomas were reported, including 57 small-diameter melanomas (10.6%). The median Breslow thickness of the small- and larger-diameter melanomas was not significantly different (0.8 mm vs 0.9 mm, respectively; P =.0527). Among participants with the small-diameter melanomas, 5 (8.9%) presented with metastasis. No significant difference was observed regarding tumor spread at presentation between the small- and larger-diameter melanomas (primary, 91.1% vs 86.2%; satellite/in-transit, 1.8% vs 0.2%; regional node micrometastasis, 5.4% vs 11.8%; and regional node macrometastasis, 1.8% vs 1.8%, respectively [P = .161]).

Metastasis at presentation was not significantly associated with small diameter (odds ratio, 0.92; 95% CI, 0.32-2.61; P =.869) after adjusting for Breslow thickness, age, sex, and ulceration in multivariate logistic regression analysis.

Data regarding progression were available for 47 small melanomas, and 5 patients (10.6%) developed metastasis. At 180 months (median follow-up, 101 months), the metastasis-free survival was 87.3%.

Study limitations include the retrospective design, and the fact that a greater number of small invasive melanomas may be needed for more robust conclusions and to assess potential prognostic factors.

“These findings raise the question of the usefulness of the ‘diameter >6 mm’ criterion, that may create a false sense of reassurance in the case of a small ‘new spot’ or a small ‘spot that has changed,’ and delay diagnosis,” conclude the researchers.

Disclosure: One of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.