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An 86-year-old man presents with a 1-year history of asymptomatic, pigmented lesions on the heel of his right foot. The patient does not recall any antecedent trauma to the site. He is currently undergoing treatment for metastatic prostate cancer and coronary artery disease. Physical examination reveals scattered, hyperpigmented macules that, on dermoscopy, demonstrated varying shades of brown primarily concentrated within the ridges. Inguinal lymph nodes were not palpable.
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Acral lentiginous melanoma (ALM) is a rare subtype of melanoma that arises on the palms, soles of the feet, and nail beds. The prevalence of ALM varies according to geography, and it is the most common subtype of melanoma in patients of African and Asian descent.1,2
Repetitive trauma may play a role in pathogenesis.3 Patients with ALM have a poor prognosis, usually because of a delay in diagnosis. In one study, the time of diagnosis ranged from 1 month to 10 years, with a mean time of 18 months.4
Dermoscopy is a very useful tool in early diagnosis of ALM; characteristic findings include irregular diffuse pigmentation and a parallel-ridge pattern.5 Lallas et al proposed a dermoscopic checklist for diagnosing ALM using a 6-variable step known as BRAAFF: 4 positive predictors (irregular blotches, ridge pattern, asymmetry of structures, and asymmetry of colors) and 2 negative predictors (furrow pattern and fibrillar pattern).6
Confirmation of diagnosis is made by histopathology that reveals atypical melanocytes in the basal layer with extension to the most superficial layers of the epidermis.
Surgical excision is the standard of care, with a poor prognosis often attributed to delayed diagnosis. Greater awareness of the prevalence of ALM in select population subsets and enhanced screening will contribute to early diagnosis and enhanced survival.1
Nejib Doss, MD, is a dermatologist practicing at the Department of Dermatology, Military Hospital of Tunis, Tunisia. Gita Faghihi, MD, is on staff at the Dermatology Department of the Isfahan University of Medical Sciences in Isfahan, Iran. Stephen Schleicher, MD, is director of the DermDox Center for Dermatology in Pennsylvania, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Desai A, Ugorji R, Khachemoune A. Acral melanoma foot lesions. Part 2: clinical presentation, diagnosis, and management. Clin Exp Dermatol. 2018;43(2):117-123.
2. Mechchat A, Elidrissi M , Bouziane A, et al. [Surgical treatment of acral melanoma: a report of eight cases] Ann Chir Plast Esthet 2015;60(1):39-43.
3. Kaskel P, Kind P, Sander S, Peter R U, Krähn G. Trauma and melanoma formation: a true association? Br J Dermatol. 2000;143(4):749-753.
4. Csányi I Houshmand N, Szűcs M, et al. Acral lentiginous melanoma: a single‐centre retrospective review of four decades in East‐Central Europe. J Eur Acad Dermatol Venereol. Published online January 27, 2020. doi:10.1111/jdv.16227.
5. Saida T, Koga H, Uhara H. Key points in dermoscopic differentiation between early acral melanoma and acral nevus. J Dermatol. 2011;38(1):25-34.
6. Lallas A, Kyrgidis A, Koga H et al. The BRAAFF checklist: a new dermoscopic algorithm for diagnosing acral melanoma. Br J Dermatol. 2015;173(4):1041-1049.
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