Dermatologic Conditions of the Feet

Dermatologic Conditions of the Feet

Patrick J. Huang

Casey M. O’Connor

Afshin A. Anoushiravani


The feet are vulnerable to a vast array of disorders due to the contact stresses from ambulation and the moist environment created by the use of footwear. This along with the poor vascularity to feet place them at significant risk for a number of dermatologic conditions which can lead to significant pain and discomfort.1 As a practitioner, it is important to understand the vast array of dermatologic conductions that can be inflammatory, inherited, or neoplastic in origin. In this chapter, we will explore the painful dermatologic conditions which affect the foot. The prompt identification and management of these dermatologic conditions can enhance a patient’s mobility, quality of life, and self-esteem.


Hyperkeratotic disorders of the foot are common in elderly patients, affecting 20% to 65% of people older than 65 years.2 Keratotic lesions, although often considered a benign diagnosis, can cause significant pain and disability for patients. Patients with keratotic lesions have difficulty ambulating, with long-term sequelae resulting in ulcerations frequently damaging deeper structures.3,4

The physiological mechanism behind the development of hyperkeratotic lesions is not fully understood. However, the response to repetitive friction or pressure underneath an osseous prominence is thought to cause accelerated keratinization while downregulating rates of desquamation, resulting in an irregular increase in the thickness of the stratum corneum.5 Active patients with a physiologic “thickening of the skin” at the plantar skin should not be considered abnormal.6 It is essential for practitioners to be able to identify and treat abnormal keratotic disorders. In this section, we will address the 4 most common types: calluses, corns, warts, and friction blisters.

Calluses (Plantar Hyperkeratotic Lesions)

The intractable plantar keratosis or callus needs to be carefully evaluated to determine whether it is a localized, discrete callus beneath a metatarsal head or a diffuse callus under multiple metatarsal heads. Diffuse lesions are larger keratotic masses often seen in active individuals which are characterized by thickening of the plantar skin without a specific margin (Figure 16.1). A well-localized intractable plantar keratosis has circumscribed edges with a central keratotic core. Although hyperkeratotic lesions may be asymptomatic, they can become painful and require treatment.6

A discrete intractable plantar keratosis with a central keratotic core is typically seen in patients with a prominent fibular condyle on the second or third metatarsal head or underneath the tibial sesamoid. This type of
lesion may be seen in patients with a cavus foot underneath the first metatarsal head or in patients with hallux valgus with a short or hypermobile first metatarsal. Conversely, a diffuse intractable plantar keratosis is seen underneath a metatarsal head that does not have a prominent condyle and these lesions typically do not have a central core. A diffuse lesion can also be seen under the second, third, or fourth metatarsal head in a patient with a Morton foot or shortened metatarsal head.6

Initial conservative treatment for a well-localized intractable plantar keratosis relies on debridement in an attempt to reduce the keratotic tissue with debridement of the central keratotic core. In a large lesion, this may require multiple bedside debridements. After the lesion has been debrided, the patient is placed in a soft metatarsal support. If the callus persists and pain from the lesion continues, surgical intervention can be considered.6

Surgical treatment depends on the etiology and can involve a spectrum of treatments from a DuVries metatarsal condylectomy to address a prominent fibular condyle to the correction of a severe cavus deformity. The surgical treatment plan needs to be patient specific identifying and addressing the underlying foot deformity.6

Clavus (Corn)

A clavus otherwise known as corn are well-circumscribed hyperkeratotic lesions with a central core that forms over a bony prominence (Figure 16.2). These lesions are painful to direct pressure and have sharply demarcated margins. There are 2 types of lesions seen: the hard corn (heloma durum) and the soft corn (heloma molle). Patients most commonly present with the hard corn which is typically seen either over the dorsolateral aspect of the fifth toe or over the dorsum of the interphalangeal joints of the lesser toes. The soft corn develops as a result of excessive moisture typically between the fourth and fifth toes.7

Initial treatment of the corn can be performed by a primary care provider and does not require referral to an orthopaedic surgeon unless there is persistent pain or recurrence of the lesions.8 Treatment should initially involve debridement with removal of the central core of the corn. Patients should then be instructed to limit the pressure to the affected area and wear a properly fitted soft-soled shoe with appropriate padding over the affected area. If conservative management fails, consultation with an orthopaedic surgeon or podiatrist to address surgical correction of any underlying foot deformity should be considered.8,9

Plantar Warts

Warts must not be confused with other lesions of the plantar foot. A plantar wart may be confused with a callus, but generally warts do not develop directly over a metatarsal head.6 Warts can give rise to tenderness
and localized pain if they occur over weight-bearing portions of the foot or may be painful secondary to footwear irritation. Plantar warts are caused by various serotypes of human papillomavirus (HPV). Warts typically start as a small shiny papule and develop into a well-defined lesions with a hyperkeratotic surface with a thickened horny ring10 (Figure 16.3). Plantar warts are typically seen in 3 different variations:

  • 1. Single or solitary wart surrounded by callus tissue.

  • 2. Multiple warts, large mother wart surrounded by tiny daughter warts or blister satellites nearby.

  • 3. Mosaic wart, usually painless and mistaken for a callus, can be quite large and appear as patches of individually coalescent cores resembling a mosaic.

Due to their etiology, they have a strong tendency to recur. Treatment with cryotherapy and salicylic acid are first-line treatment modalities. Second-line therapies include intralesional bleomycin, imiquimod, and 5-fluorouracil. Surgical excision should be avoided due to significant scar formation.11

Friction Blisters

These are typical clear fluid vesicles or bullae that appear predominantly on weight-bearing areas or areas with contact with footwear (Figure 16.4). Friction blisters are common in people who engage in wilderness and outdoor-related activities. They can be caused by physical activity or wearing a new pair of shoes or skates. Treatment involves conservative management with proper rest, footwear modification, and local wound care.12


There are many different types of discrete lesions and tumors that occur on the feet. The vast majority are benign, as malignant lesions are rare. The most common lesions include benign pigmented nevi, fibromas, keloids, plantar fibromatosis, epidermal inclusion cysts, neurilemomas, neurofibromas, lipomas, ganglion cysts, giant cell tumors of the tendon sheath, pigmented villonodular synovitis, hemangiomas, and glomus tumors and are not exclusively found on the foot. The rarer malignant tumors include fibrosarcoma, melanoma including its subungual subtype, squamous cell
carcinoma, basal cell carcinoma, synovial cell sarcoma, and Kaposi sarcoma. We will discuss a few of these lesions in more detail. Please refer Chapter 8 for more information regarding this topic.

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Sep 8, 2022 | Posted by in ORTHOPEDIC | Comments Off on Dermatologic Conditions of the Feet

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