Challenges in Diagnosing Melanoma in SOC

Ashfaq A. Marghoob, MD, director of clinical dermatology and attending physician at Memorial Sloan Kettering Cancer Center in Hauppauge, New York, and colleagues explained in a presentation at the current Maui Derm for Dermatologists meeting in Maui, Hawaii, that while several challenges in diagnosing melanoma in Black patients may delay diagnoses and result in worse outcomes, efforts at early detection may result in excessive harm from the biopsy of normally occurring pigmented macules on the palms, soles and nail unit of Black patients.¹ An early study from 1967 showed that 50% of Black patients have pigmented macules on volar surfaces, while Caucasian patients almost never have pigmented macules on palms and soles.²

The presentation highlighted the differences in identifying melanoma in Caucasian and Asian skin vs Black skin; studies that identified dermoscopic criteria for melanoma were performed primarily in Caucasian and Asian patients. In particular, the parallel ridge pattern (PRP) is considered the hallmark of identifying early melanoma on the palms and soles in Caucasian and Asian skin, Marghoob said.

However, he went on to underscore that this criterion may not be reliable in differentiating melanoma from normally occurring pigmented macules often seen on the palms and soles of Black patients. He highlighted preliminary data showing that PRP can be seen within benign pigmented macules and even in the normal background skin of the palms and soles in Black skin. In addition to PRP not being a strong predictor of melanoma in Black skin, the presentation stated that benign pigmented macules in skin of color (SOC) are often greater than 7mm in diameter and may reveal a homogeneous brown color, both features suggestive of melanoma in Caucasian and Asian skin but not likely in Black skin. Marghoob stressed that using these diagnostic criteria, which have been validated for Caucasian and Asian skin, may result in harm and unnecessary biopsies in Black patients.

In a slide adapted from a 2021 publication by Marchetti et al and published in JAMA Dermatol, the incidence of melanoma reported between 1973-2011 in Caucasian, non-Hispanic populations was 27/100,000. The incidence in Black patients was 1/100,000. However, the 5-year survival rate was 20% lower in Black patients vs Caucasians: 73% compared to 93%, respectfully.³ In an interview with Dermatology Times®, Marghoob said that there may be multiple reasons accounting for the perceived delays in diagnosis of melanoma in Black patients.

A study in the Journal of the American Academy of Dermatology suggests that less access to medical care and preventive screenings as well as the misconception that darker races, particularly black patients, never develop skin cancer, leads to decreased awareness and a lack of public and physician education on the subject.⁴ A study in the Journal of Clinical Oncology reported that even after adjusting for age, sex, histology, stage, anatomic site, treatment, and socioeconomic status, there was still a significantly increased risk of death in Black patients relative to White patients indicating that there are many factors contributing to the delay in diagnosis.⁵

Marghoob said that it is interesting to note that while the incidence of acro-lentiginous melanoma is less than 1/100,000 in both Black and white patients, it is the predominant subtype of melanoma seen in Black patients but the least common subtype in Caucasian patients. It is also interesting to note that acro-lentiginous melanoma has survival rates that are relatively similar: 83% in Caucasian patients vs 77% in Black patients.⁶

“We need dedicated studies to determine the morphology of benign and malignant skin lesions in Black patients and use this data to determine the most robust criteria to help differentiate benign from malignant lesions in this population,” Marghoobtold Dermatology Times®. “Health care equity does not mean providing the same care to all patients, but instead it means providing the most appropriate, personalized care to each individual with the aim of maximizing benefits and minimizing harms.”

References:

1. Hawrluk E, High W, Marghoob A, Sullivan R. Pigmented lesion clinic part 1. Presented at: Maui Derm 2022; January 24 to 28, 2022; Wailea, Hawaii.
2. Lewis MG. Malignant melanoma in Uganda. (The relationship between pigmentation and malignant melanoma on the soles of the feet). Br J Cancer. 1967;21(3):483-495. doi:10.1038/bjc.1967.56.
3. Marchetti MA, Adamson AS, Halpern AC. Melanoma and racial health disparities in black individuals-facts, fallacies, and fixes. JAMA Dermatol. 2021;157(9):1031-1032. doi:10.1001/jamadermatol.2021.2215.
4. Gloster HM Jr, Neal K. Skin cancer in skin of color. J Am Acad Dermatol. 2006;55(5):741-764. doi:10.1016/j.jaad.2005.08.063.
5. Zell JA, Cinar P, Mobasher M, Ziogas A, Meyskens FL, Anton-Culver H. Survival for patients with invasive cutaneous melanoma among ethnic groups: the effects of socioeconomic status and treatment. JCO. 2008;26(1):66-75.
6. Wang Y, Zhao Y, Ma S. Racial differences in six major subtypes of melanoma: descriptive epidemiology. BMC Cancer. 2016;16(1):691. Published 2016 Aug 30. doi:10.1186/s12885-016-2747-6