DermDx: Painful Bumps on Sole of Foot

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A 28-year-old man requests a consultation for bothersome lesions on the sole of his left foot. The condition first began in the center of the foot as a hard bump with new bumps arising on both sides of the original lesion. The patient notes that the sites are occasionally tender. He is a high school teacher and coach of the swim team. Examination reveals scattered hyperkeratotic slightly elevated papules. Lateral pressure on the largest lesion elicits pain. No similar lesions are noted on his right foot or palms.

Plantar verrucae (PV), also known as plantar warts, are caused by human papillomavirus (HPV). Subtype 2 of HPV is most commonly seen in mosaic warts.1 The virus can be found on floors, socks, and sporting equipment and enters the skin...

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Plantar verrucae (PV), also known as plantar warts, are caused by human papillomavirus (HPV). Subtype 2 of HPV is most commonly seen in mosaic warts.1 The virus can be found on floors, socks, and sporting equipment and enters the skin through minor trauma. Once inside the epidermis, the virus inoculates keratinocytes and continues to replicate.1

Plantar verrucae clinically present as well-defined papillomatous lesions with overlying hyperkeratosis. Verrucae clustered together are referred to as mosaic warts.2 Pinpoint bleeding upon debridement and disruption of normal skin lines differentiate PV from a plantar callus.3 Further, lateral compression on a PV induces pain whereas a callus is most painful with direct pressure. Unlike a callus, dermoscopy reveals prominent hemorrhages in PV.

Treatment of PV may prove challenging. The majority of lesions will eventually resolve spontaneously but patients often seek treatment because of discomfort or for cosmetic reasons. Home remedies include wart solutions containing salicylic acid and duct tape.2,4  Variable results have been reported with prescriptive agents including cantharidin, imiquimod, and 5-fluorouracil.5

Liquid nitrogen cryosurgery and laser ablation are office-based destructive therapies that usually require multiple sessions.6 From a prevention standpoint, patients should be educated on avoiding walking barefoot in public areas such as swimming pools, locker rooms, gymnasiums, and public showers.

Sara Mahmood, DPM, is a podiatrist who completed a joint dermatology/podiatry fellowship and is on staff at the DermDox Dermatology Centers in Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.

References

1. Vlahovic TC, Khan MT. The human papillomavirus and its role in plantar warts: a comprehensive review of diagnosis and management. Clin Podiatr Med Surg. 2016;33(3):337-353. doi:10.1016/j.cpm.2016.02.003

2. Witchey DJ, Witchey NB, Roth-Kauffman MM, Kauffman MK. Plantar warts: epidemiology, pathophysiology, and clinical management. J Am Osteopath Assoc. 2018;118(2):92-105. doi:10.7556/jaoa.2018.024

3. Cockayne S, Hewitt C, Hicks K, et al. Cryotherapy versus salicylic acid for the treatment of plantar warts (verrucae): a randomised controlled trial. BMJ. 2011;342:d3271. doi:10.1136/bmj.d3271

4. Abdel-Latif AA, El-Sherbiny AF, Omar AH. Silver duct tape occlusion in treatment of plantar warts in adults: is it effective? Dermatol Ther. 2020;33(3):e13342. doi:10.1111/dth.13342.

5. Kollipara R, Ekhlassi E, Downing C, Guidry J, Lee M, Tyring SK. Advancements in pharmacotherapy for noncancerous manifestations of HPV. J Clin Med. 2015;4(5):832-846. doi:10.3390/jcm4050832

6. Boroujeni NH, Handjani F. Cryotherapy versus CO2 laser in the treatment of plantar warts: a randomized controlled trial. Dermatol Pract Concept. 2018;8(3):168-173. doi:10.5826/dpc.0803a03.

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