Dermatologic, Infectious, and Nail Disorders

Blisters

Blisters are caused by repetitive friction between skin and shoe and/or sock. Moisture from perspiration, increased heat, and poorly fitting shoes increases the risk of blister formation. Underlying bony abnormalities of the foot may also increase the risk of formation. Blisters are formed from a split between the epidermis layers that fills with transudate. Blisters are among the most common complaints in surveys of runners and other athletes and typically appear in toes, plantar surfaces of the metatarsals heads, and heels.

Blisters appear as areas of erythema followed by formation of the vesicle or bullae ( Fig. 13.1 ). Formation is often accompanied by sensation of burning or stinging. The fluid filled lesions may appear dark when blood fills the blister cavity. Data has demonstrated that blisters are best treated with sterile drainage using a blade or needle without disturbing the roof. The roof of the blister can adhere to the base of the lesion, providing protection and decreasing risk of infection. After drainage, petroleum jelly and occlusive dressings may be used to protect the healing lesion. Commercially available products, such as hydrocolloid pads, are available that can be applied daily to promote healing (2nd Skin). Athlete and clinician should continue to monitor the affected area for secondary infection.

Prevention of blisters includes properly fitted shoeware, moisture wicking socks, and consideration of extra padding over bony prominences. Athletes have often used two pairs of socks to help distribute the frictional forces to the foot. Drying powders, such as aluminum chloride, may be used to decrease moisture around the foot. Agents such as 10% tannic acid soaks may assist in hardening the skin.

Calluses

Calluses are defined as hyperkeratotic plaques created by repeated friction and pressure on the skin ( Fig.13.2 ). Most calluses are painless, but can become symptomatic when extremely thick and place excessive pressure on underlying structures. The differential diagnosis includes plantar warts and corns. The diagnosis can be confirmed with paring of the lesion. Warts contain the characteristic black dots of tiny thrombosed vessels, while corns contain a central core. When treatment is required, gentle paring with a blade or pumice stone will debulk the lesion and provide relief. Prevention of calluses can include synthetic socks, lubricant jelly, and properly fitting shoes in order to minimize friction and pressure across the skin. In symptomatic cases, where underlying anatomical abnormalities are causative, surgical treatment may be indicated.

Corns

Corns, similarly as calluses, may present in two ways. Hard corns (clavus durus) are typically found on the sole or dorsum of the toes ( Fig.13.3 ). Soft corns (clavus mollis) are often found in the interdigital area due to pressure from one toe on another and are often painful. Diagnosis is confirmed by paring of the lesion. Corns are characterized by a central core, while calluses show normal skin lines and plantar warts the characteristic black dots. Paring will provide pain relief, and pads may help redistribute and minimize pressure. In addition to mechanical or sharp debridement, electrosurgery has been used successfully as an alternative treatmemt. Nonsurgical treatment options include warm water soaks and keratolytics (salicylic acid pads), topical or intralesional steroids, or topical retinoids. Preventive measures are similar to those for calluses and blisters.

Nodules

Athlete’s nodules have been classically described as small, flesh-colored lesions, usually occurring at the dorsum of the toes, foot, or anterior ankle and lower leg due to repetitive pressure and friction of tight fitting shoes, skates, or boots. Comparable lesions have been described on the hands of boxers and laborers. The lesions typically present insidiously and are often painless. Occasionally, the lesion may reach a critical size and cause some pressure-related discomfort that may require attention. The histology of these lesions often will show increase in collagen density in the dermis with relatively normal epidermis. The differential diagnosis can include ganglion, granuloma annulare, rheumatoid nodule, gout, foreign body reaction, and elastoma.

Treatment is often not necessary but, when symptoms dictate, can include medical treatment with topical keratolytics (salicylic acid), or intralesional injection of corticosteroid to address the thickened collagen in the dermis. Surgical removal is an option for recalcitrant cases, and would be reserved for the athlete’s off season if possible.