Introduction
Acral pigmentation may arise from a wide spectrum of etiologies, ranging from benign melanotic macules to serious conditions such as acral lentiginous melanoma.1 Benign recurrent acral pigmentation appears to be a rare, idiopathic, self-limited disorder characterized by recurrent, asymptomatic brown macules on the palms and soles that resolve spontaneously within weeks to months.2 To date, the reported cases have been sporadic. Herein, we describe what appears to be the familial occurrence of transient acral pigmentation, adding a new dimension to this uncommon presentation.
Case report
A 36-year-old woman presented with multiple, asymptomatic, brownish macules over the plantar aspects of bilateral feet, noticed over the preceding 3 months. The lesions would appear spontaneously, persist for a few days to weeks, and then fade completely, occasionally recurring in new areas. There was no preceding erythema, trauma, or drug intake prior to eruption. Interestingly, her 2 children, 1-year-old daughter and 7-year-old son developed similar pigmentation over their soles during the same period. None had systemic symptoms, mucosal pigmentation, or nail changes. There was no relevant family history in previous generations.
On examination, all 3 had multiple, discrete, brown macules (2-5 mm) on the soles, with smooth surfaces, well-defined borders, and no scaling or induration (Fig 1, Fig 2, Fig 3, Fig 4). A wipe test with alcohol was negative, and KOH mount did not reveal fungal elements.
Fig 1.
Solitary brown macule on the mother's left sole.
Fig 2.
Multiple hyperpigmented macules on daughter's soles.
Fig 3.
Multiple hyperpigmented macules on the son's soles.
Fig 4.
Multiple hyperpigmented macules on the soles of both the siblings.
A clinical diagnosis of benign recurrent acral pigmentation was made. All were prescribed a topical moisturizer and advised follow-up; however, the family was subsequently lost to follow-up. No biopsy was performed as the patient denied.
Discussion
Benign recurrent acral pigmentation is characterized by asymptomatic, transient, hyperpigmented macules over acral sites that resolve spontaneously without residual pigmentation. The etiology in this familial case remains unknown, though environmental, mechanical, and transient melanogenic triggers could have predisposed the lesions. The unique feature of the present report is the simultaneous occurrence in 3 members of a single family, suggesting either a shared environmental exposure (eg, transient exogenous pigment or irritant), a viral etiology or a genetic predisposition leading to heightened acral melanogenic response.3,4
The differential diagnoses considered were tinea nigra, exogenous pigmentation, and familial lentiginosis syndromes.3,4 However, they were ruled out by negative KOH, no indentifiable contact agent and absence of persistent mucosal involvement, respectively. Therefore, given the self-limited and recurrent course, benign recurrent acral pigmentation remains the most appropriate diagnosis, together with an atypical familial clustering. A limitation of this report is that dermoscopy was not performed on the lesions during the active phase, which might have aided in morphological characterization. No similar familial cases were found in literature to date.
This case highlights an unusual familial occurrence of benign recurrent acral pigmentation. It emphasizes the need to recognize transient acral pigmentation as a benign condition to avoid unnecessary investigations or interventions. Further reports and follow-up studies are warranted to determine whether familial clustering represents a genetic susceptibility or a shared environmental phenomenon.
Conflicts of interest
None disclosed.
Footnotes
Funding sources: None.
Patient consent: The authors obtained written consent from patients for their photographs and medical information to be published in print and online and with the understanding that this information may be publicly available. Patient consent forms were not provided to the journal but are retained by the authors.
References
- 1.Ingrassia J.P., King G., Smith M., Glusac E.J. Diagnosis and management of acral pigmented lesions. Dermatol Surg. 2023;49(10):926–931. doi: 10.1097/DSS.0000000000003891. [DOI] [PubMed] [Google Scholar]
- 2.Arif T. Recurrent asymptomatic reddish-brown pigmented macules on the palms. Our Dermatol Online. 2024;15(3):320–322. doi: 10.7241/ourd.20243.26. [DOI] [Google Scholar]
- 3.Bhalla M., Garg S. Acral melanosis. Pigment Int. 2018;5(1):14–27. doi: 10.4103/Pigmentinternational.Pigmentinternational_15_17. [DOI] [Google Scholar]
- 4.Eksomtramage T., Aiempanakit K. Tinea nigra mimicking acral melanocytic nevi. IDCases. 2019;18 doi: 10.1016/j.idcr.2019.e00654. [DOI] [PMC free article] [PubMed] [Google Scholar]