A 65-year-old man is referred by his dentist for evaluation of a dark spot on the inside of his lower lip. He reports that the spot has been present for at least 1 year. His medical history is unremarkable, and he denies antecedent trauma to the area. No similar lesions are noted within his oral cavity or on the surface of his skin. Examination reveals a well-defined hyperpigmented macule measuring 0.5cm. Dermoscopy shows uniform brown coloration with parallel lines and circles.
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The lesion on this patient’s lip was diagnosed as a labial melanotic macule, which are common benign, well-defined pigmented lesions that occur on the oral mucosa. They typically present as solitary, brown to black discolorations and are often <1 cm in size.1 Occurring in roughly 3% of the population, labial melanotic macules are most frequently seen in women and typically present on the lower lip.2
Histologically, labial melanotic macules occur secondary to an increase in melanin in melanocytes and keratinocytes of the basal layer, as well as an increase in melanophages in the dermal papillae. The number of melanocytes is typically normal or slightly increased.3
Due to their clinical appearance, labial melanotic macules can sometimes be difficult to differentiate from venous lakes or oral melanoma. Dermoscopy may be of diagnostic value; characteristic findings include homogeneous brown pigmentation, parallel and circular lines, and overlapping vessels. Dermoscopy may obviate the need for biopsy in sensitive anatomic areas.1,4
Labial melanotic macules are benign lesions that do not require treatment. If cosmetically bothersome, cryotherapy and laser therapy may be efficacious for their removal.5
Nelson Maniscalco, DPM, is a joint podiatry/dermatology fellow under the aegis of St. Luke’s Medical Center in Allentown, Pennsylvania, and the DermDox Center for Dermatology. Stephen Schleicher, MD, is director of the DermDox Center for Dermatology, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. Kim GW, Shin K, You HS, et al. Dermoscopic “landscape painting patterns” as a clue for labial melanotic macules: an analysis of 80 cases. Ann Dermatol. 2018;30(3):331-334.
2. Aljasser MI, Lam J, Lui H, Kalia S. Labial melanotic macules in atopic dermatitis: an observational study. J Dermatol Dermatologic Surg. 2019;23(2):86-89.
3. Erfan N, Hofman V, Desruelles F, et al. Labial melanotic macule: a potential pitfall on reflectance confocal microscopy. Letter. Dermatology. 2012;224(3):209-211.
4. Lee JS, Mun J-H. Dermoscopy of venous lake on the lips: a comparative study with labial melanotic macule. PLoS One. 2018;12(10):e0206768.
5. Duan N, Zhang Y-H, Wang W-M, Wang X. Mystery behind labial and oral melanotic macules: clinical, dermoscopic and pathological aspects of Laugier-Hunziker syndrome. World J Clin Cases. 2018;6(10):322-334.