R. Vender, MD, FRCPC
Faculty of Medicine, McMaster University, Hamilton, Ontario, Canada
This article will deal with the diagnosis and treatment of common eruptions on the feet. These conditions include:
Area of Foot
Useful tests include:
- KOH (Potassium hydroxide) exam of scale for fungus from skin and nail
- Use a No. 15 blade and gently scrape scale from the edge of
the plaques into the black transport paper, usually supplied by a diagnostic lab.
- Bacteriology culture swab
- Patch testing
Tinea Pedis (Skin and Nail)
- One of the most common dermatologic conditions
- Seen more often in men
- Almost always involves the lateral web spaces
- Soles involved and may spread onto the dorsal aspects, usually asymmetrically
- Nail involvement may follow from a skin infection or vice versa
- Cracking of the skin may create an entry site for bacterial infection producing secondary cellulitis
- Often asymptomatic but can be itchy
- Feet may be malodorous
- Painful if fissured
- KOH examination from the skin, subungual debris, or nail clippings confirms the diagnosis.
- Culture determines specific name of fungus. Check the dry scale or roof of blister. May be negative if significant inflammation.
- Web-space scaling and maceration. May have significant bacterial colonization.
- Dry type. Scaling can involve skin creases or the whole sole that has a powdery scale (moccasin type).
- Acute blistering. Small blisters often on instep
- Soggy white skin changes with cracking
- Nails can become involved and act as a reservoir for reinfection.
- General measures, such as changes in footware to reduce heat and sweating
- Wear cotton or absorbent socks.
- Relapses are very common with any type of tinea infection of the feet, so intermittent maintenance using topical antifungals should be considered after clearance has been achieved.
- Antifungal powders are only of value as prophylaxis.
Topical Therapy for Tinea Pedis
Area of Foot
|Dry type of infection|
|Acute type of infection|
Oral Therapy for Tinea Pedis
- Confirm with KOH and culture first.
- Terbinafine 250mg daily for 2 weeks
- Itraconazole (Sporanox®) studies suggest 400mg daily for 1 week or 100-200mg daily for 2-4weeks.
- Studies comparing these two drugs and using itraconazole at 100mg showed terbinafine to be much more effective.
- However, it is now known that a higher dose of itraconazole is required.
- Monitor appropriate blood work.
- Confirm with KOH and culture first and monitor appropriate blood work, i.e., CBC and LFTsat baseline and at 1 month.
- Ciclopirox 8% nail lacquer is effective in the milder forms of nail infection. Mycological cures in the range of 52% can be achieved.
- Adding ciclopirox 8% nail lacquer to terbinafine significantly increases cure rates.
- Terbinafine is thought to be the treatment of choice at a dose of 250mg daily for 3 months. Using this drug for 1 week every month for 3 or 4 cycles is almost as effective, reducing both costs and worries about side-effects.
Dyshidrotic Eczema (Pompholyx)
- A recurrent eruption affecting hands and feet seen mostly in young adults
- Associated with atopy, hyperhidrosis, stress and an allergic contact dermatitis
- Intensely itchy
- Tiny blisters, which may become multilocular on soles and toes
- Less commonly found in the web spaces
- If pustules are present, swab for bacterial infection such as Staphylococcus.
- Once the blisters settle there may be a dry, chronic, scaly, fissured rash.
- Compress blisters with saline, tap water, or 10% aluminum acetate for 20 minutes q.i.d. Large blisters can be drained.
- Moderate-to-high potency topical steroid creams should be used after compressing.
- Studies show that immunomodulators, such as pimecrolimus (Elidel®) and tacrolimus (Protopic®), could be added with benefit.
- Use oral antibiotics if there is a suspicion of bacterial infection, such as Staphylococcus or Streptococcus.
- Oral antihistamines can help with itch (sedation).
- In severe cases, oral prednisone (Deltasone®) for approximately 2 weeks should be utilized.
- Change to moderate-to-high potency topical steroid ointment rather than cream.
- Using a topical corticosteroid intermittently, such as on weekends only, and using topical immunomodulators on weekdays has been reported.
Juvenile Plantar Dermatosis
- Seen in childhood up to the age of 15
- A tender, glazed erythema on the weight-bearing forefoot and toes
Nonscaly and sometimes fissured
- No vesicles are observed
- Worsened by sweating; may be caused by alternating sweating and drying as experienced by those who wear ‘sneakers’.
- Rule out fungus by KOH exam.
- 10% are patch test positive.
- Minimize occlusive foot wear; change to cotton or absorptive socks.
- Mild topical steroid ointments b.i.d.
- Emollients such as petroleum jelly can be helpful.
- Occlusive ointments such as zinc paste can help some.
- Tar ointments have been reported as useful (e.g., 10% LCD in hydrophilic petrolatum).
Pustular Psoriasis of the Palms and Soles
- Creamy yellow, sterile pustules on an erythematous base
- The lesions are at different stages, and the pustules mature into a brown color and then become scaly
- 30% of patients have psoriasis elsewhere
- In children, especially infants, vesicopustules on the soles could suggest scabies.
- Mild disease can be controlled with medium-to-potent topical steroids.
- Long-term risk of atrophy. Some may respond to calcipotriol combined with a corticosteroid (Dovobet®).
- Topical UVB/PUVA is useful in some patients.
- Acitretin (Soriatane®) or methotrexate (Trexall®) for resistant disease
- Although irritant dermatitis can be seen, allergic contact is a more significant problem.
- Itchy eczematous dermatitis on the dorsal aspect of the feet raises the possibility of a contact dermatitis, especially to footwear.
- The rash may be well defined at the area of contact, e.g., shoe tongue. The condition worsens with conditions that increase sweating, and in the summer months.
- Identify and avoid the allergen.
- Patch testing is a must if there is clinical suspicion.
- Topical corticosteroids are the treatment of choice, but will not clear the condition if the allergen contact is still present.