Clinical Challenge: Dark Brown Lesions on the Foot - Dermatology Advisor

Clinical Challenge: Dark Brown Lesions on the Foot

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A 34-year-old man was referred to a dermatology clinic by his primary care physician who noticed pigmented lesions on his right foot. The patient had no prior knowledge of these lesions and was unaware of their duration. Personal and family history are negative for skin cancer. Examination reveals a 5-mm, well-circumscribed, dark brown lesion on the plantar aspect of his foot; also present is a 5-mm elongated dark brown lesion lateral to the fifth metatarsal. Both lesions exhibit linear striations with central darkening.

Biopsy is performed, revealing an acral nevus with mild atypia. Acral nevi are benign melanocytic lesions situated on the volar skin of the palms and soles. Lesions involving the nail unit also fall into this category.1 These nevi are more...

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Biopsy is performed, revealing an acral nevus with mild atypia. Acral nevi are benign melanocytic lesions situated on the volar skin of the palms and soles. Lesions involving the nail unit also fall into this category.1 These nevi are more commonly identified in women and in white individuals aged <50 years.2 Acral nevi may share similar clinical characteristics with acral melanoma, which may create a diagnostic challenge. Most benign lesions are <7 mm in diameter and flat, although compound-type congenital acral nevi can be slightly elevated. Lesions are light brown to dark brown in color with a central region that is often darker.1,3  Benign dermatoscopic patterns are parallel-furrow, lattice-like, and fibrillar.

Acral nevi require neither biopsy nor full excision, although periodic observation and monitoring for change are advised. Any volar lesion that manifests pigment on the ridges when viewed with a dermatoscope warrants histopathologic examination.4,5 

Nelson Maniscalco, DPM, is a podiatric-dermatology fellow under the aegis of St. Luke’s Medical Center and the DermDox Centers for Dermatology, and Stephen Schleicher, MD, is director of the DermDox Center for Dermatology, 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. Soyer HP, Argenziano G, Hoffman-Wellenhof R, Johr RH. Acral nevus. In: Color Atlas of Melanocytic Lesions of the Skin. 1st ed. Berlin, Germany: Springer Science & Business Media; 2007:66-74.  

2. Palicka GA, Rhodes AR. Acral melanocytic nevi: prevalence and distribution of gross morphologic features in white and black adults. Arch Dermatol. 2010;146(10):1085-1094.

3. Criscito MC, Stein JA.  Improving the diagnosis and treatment of acral melanocytic lesions.  Melanoma Manag. 2017;4(2):113-123.

4. Koga H, Saida T. Revised 3-step dermoscopic algorithm for the management of acral melanocytic lesions.  Arch Dermatol. 2011;147(6):741-743.  

5. Bodman M. Acral lentiginous melanoma: what sets it apart? Podiatry Today. 2016;29(5):32-43.