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Ominous Skin Lesion or Benign Sports-Related Imposter?

The Most Common 'Don't Miss' Diagnoses

Kelley Pagliai Redbord, MD; Brian B. Adams, MD, MPH

Sports Dermatology Series Editor:
William W. Dexter, MD


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In Brief: Sports participants of all skill levels may develop sport-specific skin problems. Many skin disorders in athletes can mimic other potentially serious dermatologic entities that can be manifestations of musculoskeletal conditions, infections, inflammatory conditions, or carcinomas. Also, some skin conditions can alert the sports physician to look for possible anabolic steroid abuse. Physicians who are familiar with the relationship between the specific activities of various sports and skin disorders common to athletes will be able to properly diagnose, manage, and treat these conditions and educate players to prevent further injury.

Many sports require players to face situations that put their skin at risk for abrasion, infection, or other damage. Many benign, sports-related skin conditions may resemble signs of more serious diseases. Cutaneous disorders differ in athletes and nonathletes in presentation, optimal treatment, and prevention strategies. Clinicians need to be able to diagnose and treat skin conditions appropriately, knowing when to assure a patient that only simple measures are needed for resolution and when to initiate care for a serious disorder.

Talon Noir/Tache Noire vs Melanoma

A benign, painless process called talon noir is caused by repeated trauma or shearing forces typically associated with sports such as basketball, tennis, football, gymnastics, or marching. Talon noir presents unilaterally on the posterior or posterolateral heel with grouped, punctate, linear, black or blue-black macules and horizontally arranged petechiae.1-3 Histology shows intracorneal hemorrhage with lakes of pigment within the thickened stratum corneum.4 It is likely that talon noir is common but unrecognized and underreported.

A similar lesion called palmar petechiae or tache noire is the equivalent diagnosis on the palm and typically occurs in athletes engaged in racket sports, weight lifting, mountain climbing, gymnastics, mogul skiing, or golfing.

Dermatologists often see referred patients who have talon noir, because primary care physicians want to rule out a possible melanocytic neoplasm, specifically melanoma. On close examination, talon noir is composed of individual punctate lesions. The stratum corneum can be pared with a #15 blade to expose the hemorrhagic material (figure 1).1 This simple test confirms the benign nature of talon noir.

Characteristic and diagnostic features of talon noir or tache noire include the site and shape of the lesion, the history of athletic activity, and the expression of hemorrhagic material. This constellation of findings should enable a correct diagnosis without biopsy and without the psychological concerns of a suspected melanoma. Sports physicians should not confuse this benign, self-healing condition with melanoma. The pigment in melanoma is deeper than in talon noir or tache noire and cannot be removed with a #15 blade. Melanoma should be suspected in darkening or enlarging lesions that are greater than 6 mm, darkly pigmented, or irregularly bordered. If melanoma is suspected, a biopsy must be performed for confirmation, and the lesion should not be pared with a #15 blade.

No treatment is required for talon noir or tache noir as the lesions resolve spontaneously. Felt heel pads in the shoe may prevent recurrences.5

Tennis Toe With Hemorrhage vs Melanoma

Painful subungual or periungual hemorrhages under the distal nail plate in the first and second toe may be tennis toe. The proximal nails are often unaffected.6 Toes slide forward repetitively with rapid stops after quick acceleration or repeated planting of the foot, causing compression in the toe box and deformation of the nail plate. This may not only lead to hematoma formation, but also to onycholysis and subungual or periungual hyperkeratosis.3,7 This nail disorder is typically seen in tennis players and is termed tennis toe, but it has also been reported in runners (jogger's toenail), skiers, hikers, climbers, and in those who play soccer, basketball, football, or squash.3,7,8 In these athletes, toenails other than the first two may demonstrate this disorder.

Tennis toe causes pain, unpleasant cosmesis, and confusion with malignant melanoma. The acute nature of tennis toe and its relationship to trauma should exclude melanoma. Furthermore, melanoma is characterized by a history of a changing lesion and involvement of the proximal nail fold (Hutchinson's sign). If melanoma is suspected, a biopsy of the nail matrix is required.

Prevention and treatment of tennis toe include performing proper nail hygiene, trimming nails straight across, wearing properly fitted shoes with adequate toe box room, and using orthoses to improve shoe fit.3,6,7,9 Decompression of a hematoma by drilling a hole through the nail plate relieves discomfort. If the hematoma involves more than 50% of the nail plate, removal of the toenail is required. If pain is unremitting, clinicians should obtain a radiograph to rule out a fracture.7

Hyperkeratotic Tennis Toe vs Onychomycosis and Psoriasis

Repeated compression and trauma in the toe box may also lead to onycholysis and subungual or periungual hyperkeratosis (figure 2A).3,7 Tennis toe with these features may be confused with onychomycosis and psoriasis, in addition to melanoma. Negative potassium hydroxide preparation and fungal culture will help exclude onychomycosis (figure 2B). Psoriasis is characterized by nail pitting, subungual debris, yellow discoloration, onycholysis, and classical cutaneous lesions elsewhere on the skin (figure 3). Nail dystrophy of tennis toe resolves with cessation of repeated trauma. Familiarity with various toenail disorders associated with athletics will help prevent misdiagnosis.

Piezogenic Pedal Papules vs Musculoskeletal Disease

Painful herniations of the subcutaneous fat into the dermis that are discernible only upon weight bearing or application of pressure are called piezogenic pedal papules.8 Structural defects of the connective tissue likely predispose patients to painful piezogenic pedal papules, suggesting that fusion of the peripheral fat chambers is caused by the degeneration of the separating trabeculae in the normal anatomy of the heel.10 Trauma may also initiate the formation of pedal papules. Multiple 2- to 5-mm, skin-colored, painful papules on the lateral or medial heels characterize piezogenic pedal papules (figure 4).

Distance runners and triathletes are more commonly affected.8,11 Piezogenic pedal papules have also been reported in patients who do vigorous physical activities and in patients exposed to repeated heel pressure.8,10-12 The associated pain may be caused by ischemia resulting from the extrusion of fat with its vasculature and associated nerves. The pain may be severe enough to limit activity.10

Diagnosis of piezogenic pedal papules can be challenging. Clinicians may do multiple tests to identify the cause of foot pain in the athlete to no avail. It is crucial to observe athletes as they stand and bear weight. It is only through this maneuver that the papules are prominent and diagnosable. Otherwise, the patient's reported pain may go misdiagnosed and the clinician may exhaust a musculoskeletal search for the cause of pain (eg, plantar fasciitis, tendinitis, heel spurs) instead of making the correct diagnosis of painful piezogenic pedal papules.

Unfortunately, only unsatisfactory treatments exist for piezogenic pedal papules. These therapies include excision, heel cups, compression stockings, acupuncture, weight loss, and repeated injections of betamethasone and bupivacaine hydrochloride.8,13-16

Pulling Boat Hands vs Raynaud's Phenomenon or Palmoplantar Hidradenitis

Prolonged mechanical injury and cold exposure may cause subcutaneous vascular injuries and epidermal blisters, a condition known as pulling boat hands.17 Pulling boat hands occur in crew team and open rowing or sailing craft members. The lesions are painful, pruritic, erythematous macules, plaques, vesicles, or bullae involving the distal dorsal hands and proximal phalanges, usually sparing the skin over the metacarpophalangeal joints and distal digits. Calluses and scarring can result. The condition frequently coexists with Raynaud's phenomenon. Analysis of the characteristic history, clinical findings, and biopsy results leads to the definitive diagnosis.

Pulling boat hands can easily be clinically confused with hand dermatitis, essential Raynaud's phenomenon, or palmoplantar hidradenitis. Signs of hand dermatitis include a pruritic and eczematous eruption, which may be acute with erythema and blisters, or chronic with erythematous, scaly, lichenified plaques. Hand dermatitis has many causes, including allergens or irritants. Usually, a history of exposure to allergens or irritants only in the involved area helps confirm the diagnosis of hand dermatitis.

About 62% of athletes who have pulling boat hands display Raynaud's phenomenon,17 usually affecting the distal fingers after exposure to cold or stress from vasospasm. The distal digits become numb and painful and turn from white to blue to red with a clear line of demarcation. Essential Raynaud's phenomenon exhibits only distinct color changes and no other epidermal changes, which distinguishes it from pulling boat hands.

The painful erythematous papules and nodules of palmoplantar hidradenitis appear similar to those of pulling boat hands, but they occur predominantly on the feet. Palmoplantar hidradenitis can also appear on the palms in mountaineers and athletes who experience repetitive strong forces to their hands. Furthermore, palmoplantar hidradenitis lacks Raynaud's phenomenon and any epidermal changes, such as scaling or blister formation. (A detailed discussion of palmoplantar hidradenitis follows.)

Treatments for pulling boat hands include topical corticosteroids, moisturizers, gloves, and fresh water soaks, but these usually fail to bring improvement. The lesions heal spontaneously within 7 days after stopping the activity.

Palmoplantar Hidradenitis vs Pressure Urticaria or Panniculitis

Intense physical activity, excessive sweating, and prolonged wetness can trigger a distinct clinical entity called palmoplantar hidradenitis.18 This occurs in children and adolescents after dancing, playing baseball, mountain climbing, or running. The cause may be sports trauma that ruptures eccrine glands and activates the complement pathway, thereby triggering a neutrophilic response. Painful, erythematous papules and nodules of abrupt onset on the soles are characteristic. Palmoplantar hidradenitis is self-limited and regresses within 1 to 4 weeks after activity cessation, but it may recur.

This little known condition can stump even the seasoned dermatologist. The differential diagnosis of the red nodules on the sole typically includes pressure urticaria and panniculitis. Pressure urticaria, like palmoplantar hidradenitis, exhibits deeply erythematous, edematous, pruritic, painful plaques at the sites of sustained pressure to the skin. It usually occurs after a delay of 30 minutes to 12 hours and frequently occurs along the waistline, the palms after manual work, the soles after walking, or on the shoulders. Pressure urticaria, unlike palmoplantar hidradenitis, resolves rather quickly, in less than 24 hours. Panniculitis, unlike palmoplantar hidradenitis, does not relate to recent athletic activity. Otherwise, the painful erythematous subcutaneous nodules associated with panniculitis can mimic palmoplantar hidradenitis. Biopsy can differentiate among the three conditions.

Treatment of pressure urticaria includes avoiding the pressure stimulus and taking antihistamines and, if necessary, systemic corticosteroids. Treatment of panniculitis is guided by the type and cause.

Calluses vs Warts

Repetitive trauma and friction cause calluses, and human papillomavirus causes warts. Both are very common dermatoses in active patients. Improperly fitted shoes may increase friction, thereby causing calluses. Well-defined hyperkeratotic, scaly papules or plaques on the hands or feet characterize warts, calluses, and corns (figure 5).

Clinically, warts and corns can easily mimic calluses. All solitary, thick plaques on the hands and feet should be pared with a #15 blade. The simple act of paring differentiates calluses, corns, and warts. After paring, a callus still demonstrates normal skin markings and ridges. In contrast, warts display black, pinpoint, thrombosed capillaries and a loss of skin markings, and corns exhibit a central core.3 Sports physicians should also remember that warts can occur in calluses; therefore, the clinician needs to carefully examine the hyperkeratotic plaque.

Treatment for calluses is usually unnecessary, because calluses may impart a competitive advantage. In sports such as gymnastics, weight lifting, and racket sports, calluses allow the athlete to withstand repetitive trauma without pain. If treatment is necessary, paring with a #15 blade, using topical keratolytics (eg, salicylic acid, lactic acid, urea), or debriding with a pumice stone after softening by soaking in warm water for 5 to 10 minutes may be helpful.2,7,19

Preventive measures for calluses include wearing properly fitted shoes and moleskin pads at sites of constant friction.7 Treatments for warts include paring with a #15 blade followed by liquid nitrogen application twice for 5 to 10 seconds. Imiquimod used daily under duct tape for warts on the hands or feet or salicylic acid preparations may clear warts as well. Athletes often prefer to try these less invasive strategies first, because they will not experience pain that may interfere with training sessions or that may alter their gait or pivot points.

Runner's or Rower's Rump vs Extramammary Paget's Disease

Small ecchymoses on the superior portion of the gluteal cleft in distance runners may be caused by constant friction.7 A history of distance running confirms the diagnosis. Runner's rump is inconsequential and resolves slowly with time after cessation of running. Runner's rump should not be confused with rower's rump, in which scaling plaques on the buttocks are caused by chronic rubbing on the seat of a rowing machine. Biopsy of these plaques reveals a chronic lichenified dermatitis (ie, lichen simplex chronicus). In cyclists, these lesions are called rider's rump. Topical corticosteroids clear rower's and rider's rump. Using extra padding can help prevent either skin eruption.

Sports physicians must differentiate rower's or rider's rump from extramammary Paget's disease, which produces a slowly expanding, pruritic, burning, well-defined, erythematous plaque with scattered areas of scale and erosions in the perianal region. Extramammary Paget's disease will not respond to topical steroids, as rower's and rider's rump do. Biopsy of the affected area reveals the characteristic histopathologic findings of extramammary Paget's disease.

Exercise-Induced Anaphylaxis vs Cholinergic Urticaria

A severe, potentially life-threatening, physical allergy that is induced by athletic activity, exercise-induced anaphylaxis (EIA) develops quickly after the start of exercise and frequently occurs in athletes with atopy.20 Signs include pruritus, urticaria, angioedema (especially on the extremities), respiratory distress, and possible vascular collapse secondary to complement activation and/or histamine activation.21 The systemic manifestations do not universally occur.

Clinicians may diagnose typical cholinergic urticaria on cursory examination or during episodes without systemic manifestations (figure 6). Cholinergic urticaria is a physical urticaria, but it is precipitated by an increase in core body temperature. The size of the hives in cholinergic urticaria tend to be smaller, and vascular collapse does not occur. Further distinguishing the two conditions, EIA can occur without the typical wheals of cholinergic urticaria, and EIA displays associated laryngeal edema. Sports physicians should specifically inquire about the history of associated systemic symptoms in athletes who have seemingly straightforward urticaria.

Treatment of EIA includes epinephrine, antihistamines, and, if necessary, vascular and respiratory support. However, prevention is paramount. Preventive measures include premedicating with a long-acting antihistamine, carrying an epinephrine pen to abort severe episodes, and never exercising alone. Some athletes can decrease episodes by not taking nonsteroidal anti-inflammatory drugs and not eating before exercise. Treatment of cholinergic urticaria includes avoiding known triggers and using antihistamines or corticosteroids.

Signs of Anabolic Steroid Use

Patients who are using anabolic steroids may exhibit striae distensae, alopecia, keloids, nodular acne, a change in sexual characteristics, or mood disorders.2 These conditions may arise without steroid use, but their presence should raise suspicion.2 Anabolic steroids increase cholesterol and free fatty acids in skin surface lipids and subsequently increase sebaceous gland size, thus contributing to acne.22 Keloids can also result from rapid muscle development.23

Striae can also occur without anabolic steroid use after intense sports that cause continuous and progressive stretching of the skin, such as weight lifting, football, wrestling, and gymnastics.24 Physicians and coaches need to be aware of these cutaneous findings to help identify athletes who are using anabolic steroids and need counseling. The acne related to anabolic steroid use will resolve after discontinuation of steroids, but it may result in scars. Anabolic steroid use results in permanent striae, alopecia, and keloids.

Treatment of striae distensae, including topical tretinoin and laser therapy, is difficult and often produces poor outcomes.7,24

Swimming Pool Granuloma vs Skin Cancer

An atypical mycobacterium found in fresh and salt water and aquariums known as Mycobacterium marinum causes swimming pool granuloma. Patients develop erythematous, indurated, variably ulcerated plaques or nodules over the dorsal hands, feet, knees, or elbows at the site of inoculation (figure 7). Multiple lesions are seen along the lymphatics.

Skin cancer, including basal cell carcinoma and squamous cell carcinoma, can affect the same locations as swimming pool granuloma. Basal cell carcinoma is typically seen as a telangiectatic, pink, pearly papule or nodule, but other (not unusual) types exhibit erythematous scaly plaques. Squamous cell carcinomas are erythematous, thick, keratotic, occasionally ulcerated papules, plaques, or nodules that may bleed with slight trauma. Biopsy confirms basal cell carcinoma or squamous cell carcinoma; a high index of suspicion is crucial.

Swimming pool granuloma and carcinomas can be difficult to distinguish. Morphologically, they may appear identical. Athletes who are unresponsive to therapy for presumed swimming pool granuloma must have a biopsy. Typically, a history of trauma and exposure to water or fish tanks suggests the possibility of M marinum infection; however, clinicians should also perform a biopsy for histopathologic analysis and culture. A swimming pool granuloma culture may take several weeks to become positive. A dermatopathologist nearly always can differentiate a malignancy from swimming pool granuloma.

Treatment of swimming pool granuloma consists of minocycline hydrochloride, sulfamethoxazole and trimethoprim, or a combination of rifampin and ethambutol hydrochloride for 3 months.25 Skin carcinoma requires surgical excision.

Turf Toe vs Gout

A sprain of the great toe that produces erythematous tender swelling and acute tendinitis of the flexor or extensor tendons of the first toe is called turf toe.3,7,26 Quick stops and turns in soft-soled shoes, which allow more flexibility on hard artificial turf, may contribute to the development of turf toe. Athletes who participate in sports such as lacrosse, field hockey, soccer, or football on artificial turf are at risk.

Gout may mimic turf toe. Gout is seen in middle-aged men who have severe, acute, tender, erythematous swelling over a joint, usually the first metatarsophalangeal joint. Fever may accompany gout.

Clinicians must differentiate between these two conditions. They may clinically appear similar, but turf toe lacks fever and gout lacks a history of athletic participation on artificial turf.7 Clinicians should ask about a history of gout and obtain a serum uric acid level, if warranted. The treatment of choice for turf toe consists of rest and wearing footwear designed for artificial turf.

Runner's Purpura vs Thrombocytopenic Purpura

Multiple authors have documented exercise-induced purpura.27-29 Most often these nonblanching erythematous patches develop on the lower extremities after vigorous exercise, but they have also appeared on sun-damaged cheeks during running. Sports physicians should recognize these findings in association with vigorous sports activity.

Purpura and petechiae occur in athletes, but physicians should also ask about any systemic symptoms, such as excessive malaise, fever, chills, night sweats, and weight loss. Several systemic illnesses cause thrombocytopenia, thus resulting in purpura or petechiae. Sports physicians should also be sure to differentiate noninflammatory purpura from vasculitis, which exhibits necrosis and peripheral blanching erythema in addition to nonblanching erythema (figure 8).

Runner's purpura fades after several days but may recur with further exercise. Prevention includes compression. The treatment of thrompocytopenic purpura is guided by the cause. Vasculitic lesions should prompt immediate referral to a dermatologist.

Prominent Points

Skin problems are common in athletes. Team physicians and dermatologists frequently examine sports-related dermatoses that can mimic other, occasionally serious, dermatologic conditions. The skin also offers a window into the patient's overall health, and sports physicians should watch for hints of illicit substance abuse. Knowledge of benign skin conditions that mimic more serious ailments is critical in making accurate diagnoses, implementing appropriate treatments, and educating patients about proper preventive measures.


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Dr Redbord is a resident and Dr Adams is an associate professor and director of sports dermatology in the Department of Dermatology in the College of Medicine at the University of Cincinnati. Dr Adams is also the chief of dermatology at the Veterans Administration Medical Center in Cincinnati. Address correspondence to Brian B. Adams, MD, MPH, PO Box 670592, Cincinnati, OH 45267-0592; e-mail to [email protected].

Disclosure information: Drs Redbord and Adams disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.