A 9-year-old boy presented with persistently moderate pruritic and reddened skin on the superior parts of the anterior shins. This occurred during the spring and summer seasons over the last 2 years. He had become an active soccer player during the past 2 years and played organized soccer in the spring and summer. He usually wore shin guards and protective cloth liners between the shin guard and his shin. However, the liner was short and did not cover the entire shin.
The rash was found on the skin below the knee and above the top edge of the protective liner, in an area where the shin guard still made direct contact with the skin. Occasionally, when he forgot to wear the liner for several days, the whole shin displayed similar symptomatology. There were no other associated symptoms, such as joint pain or nail findings, and no history of exposure to any individuals with a similar skin rash. His parents found that using a low-potency corticosteroid cream and a moisturizer provided moderate relief.
Physical examination revealed thickened erythematous patches with areas of excoriation along the shin bilaterally and especially just below the knee cap area. The rest of the physical examination was unremarkable.
What is Your Diagnosis?
a. Contact dermatitis
c. Tinea corporis
Answer on page 2
This patient had shin guard dermatitis, which is a form of contact dermatitis (CD). CD is an inflammatory skin disorder that is caused by contact with a specific chemical or physical substance. It can be acute or chronic in nature. There are 2 types of CD: irritant CD (ICD) and allergic CD (ACD). A number of athletes and active sports participants experience skin irritation and dermatitis in areas that are covered by sports equipment to protect against injuries to the body. With the increasing popularity of soccer and various sports, CD secondary to protective equipment such as shin guards may present more frequently at the medical office.1-5
There is a paucity of information in the literature regarding the prevalence of shin guard dermatitis. The lack of data in this area is surprising as there are many sports participants who wear shin guards.2,3 According to the Canada Soccer 2017 Report, more than 800,000 Canadians participated in soccer, and 75% of players were youths.6 In United States high schools alone, there are over 800,000 soccer participants.7 Clearly, given the great number of participants in soccer, more studies are required to establish the true prevalence of shin guard dermatitis.
Due to the current lack of studies in this area, it is still unclear whether the irritant or the allergic type of CD is more common. Weston and Morelli found that patch testing was negative in all 8 participants with shin guard dermatitis and concluded that most shin guard dermatitis is likely a form of ICD.3 The frictional forces and irritating contact between the skin and the protective equipment can lead to CD. Occlusion by the shin guard along with intense physical activities can increase sweating in the area and create very moist skin, both of which can exacerbate the problem.
With ICD, prior sensitization is not required.4,5 The intrinsic toxicity of the irritant and the mechanical irritation of the skin activates the innate (but not adaptive) immune responses, resulting in the release of chemokines/cytokines and inducing a local proinflammatory reaction in the skin.
On the other hand, Powell and Ahmed found that 6 of 8 patients (4 boys and 4 girls) with shin guard dermatitis had positive patch testing to either the shin guard or the material covering the shin guards.2 The identified allergens were: carba mix, mercapto mix, black rubber mix, thiourea, diethythiourea, dyes, and N-(cyclohexylthio)phthalimide.2 The authors suggested that ACD may be more common than was previously thought. Hill and Jab performed the patch tests on 3 patients, aged 12, 13, and 14 years, with shin guard dermatitis.1 All 3 patients were found to be sensitized to p-tertiary-butyl formaldehyde resin.
ACD is a type IV delayed hypersensitivity response.4,5 In the sensitization stage, the hapten (irritant) binds to the epidermal proteins. The hapten-protein is presented to the T cell by the antigen presenting cells on the major histocompatibility complexes. In the elicitation phase, subsequent exposure leads to primed T cells releasing various cytokines and chemotactic factors that result in the clinical picture seen in allergic CD.
Most patients with shin guard dermatitis present with mild irritation to moderate and severe dermatitis.5 The morphologic presentation of CD may not be distinguishable from other types of endogenous dermatitis. The dermatitis can be acute, subacute, or chronic, depending on length of exposure. The distribution is in the area of the anterior shins that come into direct contact with the shin guards. The lesions are often well-demarcated, erythematous papules or plaques with or without secondary excoriations. Acute and subacute lesions may be associated with vesicles and weeping. Chronic lesions may be associated with lichenification and scaling. The lesions are often pruritic in the allergic form. If due more to an ICD, then stinging or burning may be noted.
The diagnosis of shin guard dermatitis is generally based on a detailed history, close physical examination of the lesions, and, if necessary, patch testing.5 Referral to a dermatologist should be considered if the clinical diagnosis is uncertain.
Differential diagnoses include atopic dermatitis (AD), psoriasis, cellulitis, and tinea corporis. Intensive pruritus and cutaneous reactivity are the hallmarks of AD.8 The lesions of AD can be acute, subacute, or chronic; they are usually symmetrical. Acute lesions are intensively pruritic, erythematous papules, papulovesicles, or weeping lesions.9 Subacute lesions are erythematous scaling papules or plaques. Chronic lesions are characterized by prominent scaling, excoriations, and lichenification in the classically affected body areas. In older children and adolescents, the neck and antecubital and popliteal fossae are typically involved.
Plaque psoriasis or psoriasis vulgaris, the most common variant of psoriasis, is characterized by sharply demarcated erythematous plaques with adherent silvery micaceous scales.10 Removal of the scales results in fine punctate bleeding, which is referred to as the Auspitz sign. The lesions are usually symmetrically distributed and may be pruritic. Typical sites include the knees, elbows, and lower back. Involvement of the scalp, face, and the intertriginous and diaper areas is more common in infants and young children. Mucosal involvement is unusual. Other variants include guttate psoriasis, pustular psoriasis, erythrodermic psoriasis, and inverse psoriasis.
Seronegative inflammatory arthritis develops in about 5% to 20% of patients.10 Many patients eventually develop nail involvement. Nail involvement precedes the skin lesions in approximately 4% of patients.10 Nail involvement includes pitting, discoloration (eg, “oil drop sign”), onycholysis, or onychodystrophy.
Cellulitis can be distinguished from CD by diffuse swelling, erythema, and significant pain. The condition may be accompanied by fever and leukocytosis.
Tinea corporis typically presents as a well-demarcated, annular, erythematous plaque with a raised leading edge and scaling. The border may be papular, vesicular, or pustular. The lesion spreads centrifugally and clears centrally to form the characteristic lesion commonly known as ringworm. Mild pruritus is common.
Shin guard dermatitis may be secondary to ICD, ACD, or a combination of the two. Morphologically, ICD and ACD look similar. Patch testing (performed on the back) may be used to provide more information on the etiology of the CD. As mentioned in one of the studies, the patch testing must involve an extensive series of allergens.4 The authors suggested using the broad screening series, rubber series, and textile series, as well larger sections of the shin guard material (3-cm sections).
The key to management is the avoidance of the offending agent. Soccer players, particularly those who participate in organized play, are required to wear shin guards. Since not all shin guards are made of the same material, the players can try different brands of protective gear. Furthermore, the players can wear fabric protective liners before putting on the shin guards. Some manufacturers include these liners in their products.1-3
A moisturizer may also be useful in maintaining the skin barrier function of the skin. The use of a mild soap or gentle cleanser in washing is preferred to most soaps, which are drying. Some patients will require the application of a corticosteroid cream or topical calcineurin inhibitor in conjunction with avoidance of the offending agent to manage their skin problem.1-3 n
Dr Wong is an assistant clinical professor of family medicine at the University of Calgary. He is the site leader of the Carewest Sarcee Transition Care Unit and the co-founder of Group 23 Sports Medicine Clinic in Calgary, Alberta, Canada.
Professor Alexander Leung is a clinical professor of pediatrics at the University of Calgary and pediatric consultant at the Alberta Children’s Hospital in Calgary, Alberta, Canada.
Dr Barankin is a dermatologist, medical director and founder of the Toronto Dermatology Centre in Toronto, Ontario, Canada.
Professor Hon is a professor of pediatrics at the Chinese University of Hong Kong, Hong Kong.
1. Hill H, Jacob SE. Shin-guard dermatitis—detection and protection. Pediatr Dermatol. 2016;33(3):355-356.
2. Powell D, Ahmed S. Soccer shin guard reactions: allergic and irritant reactions. Dermatitis. 2010;21(3):162-166.
3. Weston WL, Morelli JG. Dermatitis under soccer shin guards: allergic or contact irritant reaction? Pediatr Dermatol. 2006;23(1):19-20.
4. Esser PR, Martin SF. Pathomechanics of contact sensitization. Curr Allergy Asthma Rep. 2017;17(12):83. doi:10.1007/s11882-017-0752-8
5. Bains SN, Nash P, Fonacier L. Irritant contact dermatitis [published online October 6, 2018]. Clinic Rev Allerg Immunol. doi:10.1007/s12016-018-8713-0
6. Canada Soccer 2017 Annual Report. https://issuu.com/canadasoccer/docs/20180505_cansoccer_annualreport2017. Published May 4, 2018. Accessed October 15, 2018.
7. Statista. Number of participants in U.S. high school soccer from 2009/10 to 2017/18. https://www.statista.com/statistics/267963/participation-in-us-high-school-soccer/. Published August 2018. Accessed October 15, 2018.
8. Hon KL, Leung AKC, Leung TNH, Lee VWY. Investigational drugs for atopic dermatitis. Expert Opin Investig Drugs. 2018;27(8):637-647.
9. Hon KL, Leung AKC, Leung TNH, Lee VWY. Complementary, alternative and integrative medicine for childhood atopic dermatitis. Recent Pat Inflamm Allergy Drug Discov. 2017;11(2):114-124.
10. Leung AK, Robson WL. Psoriasis. In: Lang F, ed. The Encyclopedia of Molecular Mechanisms of Disease. Berlin, Germany: Springer-Verlag; 2009:1750-1751.