Fungal Skin Infections

Most pediatricians appear to be familiar with candidal diaper dermatitis, but there is a lack of knowledge about other, less common fungal infections in children.After completing this article, readers should be able to:Candidal diaper dermatitis is the most common fungal infection of childhood. This yeast infection almost always secondarily invades diaper-area skin that has been damaged by an irritant contact dermatitis from maceration, urine, and/or stool. Children in the preschool-age group who no longer wear diapers are more likely to develop tinea infections, particularly tinea capitis. Tinea refers to dermatophyte infections in the epidermis and areas high in keratin, such as the hair and nails. In prepubertal children, tinea capitis and tinea corporis are most common; in adolescence, tinea pedis (TP), tinea cruris, and tinea unguium (onychomycosis) are more common. (1) Yeast infections other than candidal diaper dermatitis, including pityriasis versicolor (PV) (formerly known as tinea versicolor) and mucocutaneous candidiasis (MC), may also occur. Chronic MC (CMC) is a rare, usually inherited disorder. PV is a common infection in adolescents and adults that usually affects the sebum-prone areas (face, chest, back). Fungal infections can be a substantial source of morbidity in the pediatric population, accounting for about 15% of pediatric outpatient visits in the United States. (2)This article reviews the epidemiology and clinical presentations of tinea infections (capitis, corporis, pedis, cruris, unguium), PV, and MC in children. The differential diagnosis and methods for confirming diagnosis based on clinical presentation are discussed. Recommended treatment options for each type of infection are specified (Table 1). Of note, many recommendations are off-label, as the safety of many agents has not been established for children.Tinea capitis, a communicable fungal infection of the scalp and hair shaft, is the most common fungal infection in children. (3) The prevalence ranges from less than 1% in western Europe to as much as 50% in Ethiopia where the infection is endemic. (4) In North America, the prevalence is estimated to range from 3% to 8% in children. It is unclear whether it is increasing, but immigrant populations, particularly those from Africa, are at higher risk. (5) Tinea capitis most often affects children between ages 3 and 9 years, those of African heritage, those of low socioeconomic status, and those residing in urban settings and/or crowded living conditions. (1)(4) Prior to the 1950s, Microsporum audouinii was the major source of tinea capitis in North America. (6) Subsequently, epidemiology shifted and currently about 95% of tinea capitis in North America is caused by Trichophyton species (predominantly T tonsurans). Microsporum species, (7) usually transmitted by pets, causes the remainder of the cases. However, in central and southern Europe as well as in developing countries, M canis is the most common causal species. (7) It is important for clinicians to be aware of the predominant pathogen in their communities because this has implications for optimal treatment choice.Tinea capitis may be difficult to diagnose because clinical signs may be subtle and can vary substantially from child to child. Symptoms may include scaling, alopecia, broken hair shafts at the scalp, erythema, pustules, and/or large boggy scalp masses. Patients may complain of pruritus or tenderness, and occipital and posterior cervical adenopathy are often present (Fig 1). A nonspecific, eczematous, pruritic eruption may be noted on the trunk and extremities either before or during treatment; this is known as an autoeczematization or dermatophytid (id) eruption. Tinea capitis typically presents as 1 of 6 clinical patterns: gray type, black dot, diffuse scale, pustular type, favus, and kerion. Gray type is characterized by circular patches of alopecia and marked scaling with or without erythema. (4)(8) Black dot presents with patches of alopecia and is dotted with broken hair stubs (“black dots”). Diffuse scale is characterized by widespread scaling and is dandruff-like, with or without erythema. Pustular type presents as alopecia with scattered pustules, scaling, and lymphadenopathy. Favus has distinctive yellow cup-shaped crusting around the hair called scutula, along with patchy alopecia and generalized scale; this variant is extremely rare and not usually seen in the United States. Kerion is a boggy tumor with pustules, lymphadenopathy, erythema, and tenderness. (4)(8) It is the most severe inflammatory response and can be caused by either T tonsurans or M canis. (9) When children present without distinguishing characteristics of tinea capitis such as black dot alopecia or kerion, diagnosis may be simplified by recognizing clusters of symptoms. Hubbard (10) found that children with adenopathy, alopecia, pruritus, and scaling were most likely to have a positive culture. Some dermatologists now use scalp dermoscopy (visualization of scalp and hair shaft with magnification and light) to increase diagnostic accuracy; corkscrew and comma-shaped hairs are frequently seen in fungal scalp infections. (11)Because of its broad and varying symptoms, tinea capitis has a substantial differential diagnosis. Among the possibilities are alopecia areata, atopic dermatitis, bacterial scalp abscess, seborrheic dermatitis, trichotillomania, traction alopecia, psoriasis, lichen planopilaris, lupus erythematosus, syphilis, and Langerhans cell histiocytosis (Table 2). (1)(3)(6)Clinical diagnosis should be confirmed via either potassium hydroxide (KOH) microscopy or culture. Culture is preferable because speciation is provided, allowing determination of the most appropriate treatment option. Polymerase chain reaction (PCR) evaluation of dermatophyte infections has become much more cost effective and “kits” are now available, which is likely to lead to wider availability of this exceedingly rapid and sensitive test in the next few years. At this time, PCR appears more sensitive for nail and skin infections than for hair samples. (12) Wood’s light examination causes Microsporum species to fluoresce, but most infections in North America are caused by T tonsurans, which does not fluoresce. (13) Pathogens that do fluoresce include Microsporum species and Trichophyton schoenleinii. (7) Under microscopic analysis, an infected hair can present with mycelium (mass of fungal hyphae) on the external surface of the hair shaft (ectothrix) or with mycelium within the hair shaft (endothrix). (7) A favus infection presents with fungal hyphae and characteristic airspaces within the hair shaft. (7) Wood’s light analysis takes minutes to complete compared with 1 to 4 weeks required for culture results, which are accompanied by low culture-positive rates, all of which may delay treatment and increase the spread of infection. (10)A reasonable course is to start treating children with typical presentations before culture confirmation, although a culture should be attempted. Samples may be obtained either from plucked hairs or cotton swabs that have been premoistened and rolled over the affected site and are inoculated into transport culture. (14)Kerion (abscesses filled with purulent exudate) should be treated aggressively with systemic antifungal medication pending laboratory results because if left untreated, permanent hair loss and scarring may occur. Unfortunately, the degree of inflammation noted in a kerion is not linked to the fungal burden, and cultures may sometimes be negative. However, every attempt should be made to swab the kerion area as well as other areas of the scalp with a cotton swab.Tinea capitis infection may spread from the scalp to other areas of the body (eg, causing tinea corporis) and secondary bacterial infections (eg, Staphylococcus aureus) may occur. (15) If children are unlikely to have an infection (eg, no adenopathy and scaling), experts recommend confirming infection via KOH microscopy or a culture before treatment. (4)Systemic treatment is required to penetrate hair shafts. Traditionally, griseofulvin was considered the treatment of choice, (16) but a Cochrane collaborative analysis found that terbinafine, fluconazole, and itraconazole are as effective as griseofulvin, with shorter periods of treatment with newer antifungals achieving similar results to griseofulvin. (17) For Trichophyton species, terbinafine is preferable, but this agent is not as effective as griseofulvin for Microsporum species. (17)(18) When a child presents with a lesion highly suspicious for Microsporum species (eg, infected cat or dog at home, and/or lesion fluoresces under Wood’s lamp), griseofulvin should be used. Most experts believe that effective treatment doses of griseofulvin should be higher than advised in the package insert (Table 3). If griseofulvin is not available or terbinafine is preferred, the duration of treatment for Microsporum species may be longer compared to the duration for Trichophyton species. The duration of treatment for terbinafine is generally 4 to 6 weeks, and continuing treatment for 2 weeks after symptoms resolve may be beneficial. (8) Griseofulvin therapy is generally used for 8 weeks, but many experts reevaluate a child after 4 to 6 weeks of therapy to consider discontinuation. Some systemic antifungals, such as itraconazole and fluconazole, have been successfully used for pediatric tinea capitis, but such use is off-label, and a large multinational study investigating fluconazole reported cure rates below those seen with either griseofulvin or terbinafine. (40) Nonetheless, fluconazole has been widely used in children for candidiasis and may be an option when other agents are either not available or not covered by the patient’s insurance plan (Table 3).Adjunctive therapy with either selenium sulfide shampoo (1% or 2.5%) (41) or ketoconazole shampoo should be used to decrease the spread of infection. (1)(42) Because tinea capitis is communicable, children should not attend school or child care until treatment has started. Once treatment has begun, the child may return to school but should not share combs, brushes, helmets, or other items that come in contact with the scalp or play contact sports for 14 days to avoid transmission. (1) Household members should be queried and clinically examined for signs and symptoms if possible and mycologically tested if these exist. The use of selenium sulfide shampoo or ketoconazole shampoo prophylactically (2 times/wk for 2-4 weeks) is controversial, and no clear evidence-based data support its use for this purpose, although some experts recommend this. Some also recommend the same prophylaxis for people outside the home in close contact with the child. (1)(4) Close contacts include other children seen daily, such as in a classroom or child care. Although this process may seem daunting, families at least should be informed so that children can be monitored for signs and symptoms and given the option to engage in prophylactic treatment.In some cases, patients may develop an immune response to the fungus triggered by treatment, known as an id reaction. It often presents as a pruritic, papular, or on the and body and may be by and systemic However, an id reaction does not treatment and may before of This reaction should be from a but id are much more common. corporis is a dermatophyte infection of the often to as It can be caused by dermatophyte that Among children, infections may be caused by M canis from contact with dog or cat However, in North America, it is most caused by Trichophyton species, T tonsurans and Trichophyton Tinea corporis may be spread by close body contact and has been found to be more in and and corporis where it is often to the and but may also the corporis presents as a or that may spread and that to be and clear in the The generally are to a few on the body and are usually (Fig 2). erythema, pustules, or can and the may be The of and inflammation to be more common with infections caused by M canis infections are often caused by T In inflammatory are more common patients who have used Because the use of (eg, when atopic dermatitis is may the of tinea corporis should use clinical in a for KOH microscopy for skin particularly for those that have an differential diagnosis of tinea corporis psoriasis, pityriasis or atopic dermatitis, and seborrheic often have characteristics that from tinea For is has no scaling, pustules, or and is often with no and present on the of the or (1) the epidermis is not inflammation is in the (4) is less likely to have central and has more scaling is characterized by without (1) For to (1) and can be confirmed with KOH microscopy or a although cultures are usually not antifungals are generally effective and should be used for 1 after symptoms Some have that and terbinafine are more effective than and (3) the infection and should not be used. When or infections antifungals may be This is often the for those who have with those who have infections, and for who are because often have and severe infections. Because tinea corporis is more common in and the skin should be and to known as is caused by T and Trichophyton is most common adolescents and is rare prepubertal children. is estimated to be 3% to in children. Because is children, it is often This can be because treatment with may the clinical diagnosis of include erythema, scaling, maceration, and pruritus between the to the and sometimes the of the (Fig 3). may (1) The 3 typical presentations are dermatitis and is the most common presentation and is characterized by scaling between the and (9) because for this to be the most maceration, pruritus, and of the that may spread to the and of the This presentation often in the where and are (9) is typically and is characterized by scaling patches or on the and of the and or This presentation may also infection of the (onychomycosis) and (9) The presentation is characterized by and that are often on the or but can on all areas of the often accompanied by infections. may appear similar to contact dermatitis, and psoriasis, although is generally more likely to the (3) However, that should be as a differential diagnosis for every child who presents with a dermatitis can be from because the generally the (1) presents with on the of the and often the Children with may have an atopic is characterized by skin the of the and usually other and presents with gray or scale, nail or other nail and a with a typical diagnosis based on may be when the presentation is KOH microscopy or a culture is (1) KOH microscopy may be difficult with presentations because should be from the of the antifungals such as or are usually effective in treating with the duration of therapy from 1 to 4 weeks based on the agent (Table 3). treatment is generally or terbinafine. If such therapy is the should be and other agents can be including and (3) of other is a as This agent as a and and is in Patients should their before with cotton also is such as (eg, may be used if there is or may particularly if secondary bacterial infection is the infection is or the is or or presents in patients or as systemic therapy (eg, terbinafine, fluconazole, may be In type treatment is typically for the spread of (9) maceration, bacterial infection also may with tinea capitis, an id reaction may with treatment, but the is usually the to in affects and it is less common children. include crowded living or in the in a sports and a fungal infection on of the In North America, is most often caused by T although is also a common It can be spread by such as and as well as by in and A who has tinea may also have tinea pedis because can be caused by T the should always be examined in a child with tinea on the with that generally spread to the and the It usually the to candidal and is characterized by erythema, scaling, or that can become or pustules, and often to tinea corporis, there is usually less central and Tinea is typically and of the skin may as well as of the This may the of an infection the However, the may be if candidiasis is also presentation can be if the use of results in contact differential diagnosis of tinea candidal psoriasis, and seborrheic Tinea is generally the of these that does not the and (1) of candidal include of the and (1) is typically and does not have a It can be from tinea under Wood’s light as it fluoresces is by and may nail dermatitis scaling in the and are generally not (1) Tinea may also appear similar to contact dermatitis, lichen pityriasis Langerhans cell and microscopy of skin from the of the lesion should be used to diagnosis. in the of as the as well as a or may be if is A culture can also be used to diagnosis. PCR may be the diagnostic option of in the with antifungals, including and is usually should be as on the affected area and 2 to 3 terbinafine, or fluconazole may be to or infection. Griseofulvin is not because it to in the treatment with and ketoconazole is also not treatment, the affected area should be and patients should wear and use a for the area after widely to as to for fungal infection to and/or is a that usually systemic The prevalence of in has been estimated at include members with and/or and of in The most common are the T and Trichophyton are more although caused by yeast may be seen in children than 6 years. of tinea unguium may include and from to and/or of all or of the nail (Fig is the most common in all but which is characterized by is more common in children. may 2 or more affected on the same or of the and may be When 1 is the of a should be and evaluation should be particularly if the does not to antifungal of have similar presentations to including nail psoriasis, and a may lead to of symptoms from because children have nail and nails. be confirmed with before systemic positive KOH or and positive fungal culture are required for diagnosis. therapy may be before but of the for of the most appropriate systemic if available, may also be used and results more than nail with no for of the use of antifungals in of systemic was the antifungal available in North America, is available in the clinical has the of in children. and and in The safety and of these antifungals have not been established in children. However, in a child with particularly if there is no of the nail and in more severe the and may be considered and may also be an option for adolescents who are about the of their as there is that these antifungals can penetrate the nail in the of a of nail these agents are is not on the of in treating to recommend their to systemic antifungal are for children with established severe and fluconazole are and are effective (Table 3). patients should not be on systemic antifungals until their other care clinicians are in the because the of their use for may not the (eg, rare antifungal and may be a option for such have varying of in treating with systemic antifungals more effective at fungus than should be treated with members for and/or and patients and families to and and in to fungal can to (formerly tinea versicolor) is a fungal infection of the skin caused by of species of yeast in the is the most with and also common. PV is not because species are of the skin are more likely to in and PV more common in the or in PV is more common in adolescents and adults than in children because may fungus is characterized by or or with scale and a It is often based on clinical are generally to the and all of which are areas with a high of The particularly the is also affected in children. are generally although some patients scale may be difficult to and the scale a or of a a scale that can in diagnosis. and do not resolve with many may be required for skin to a include pityriasis pityriasis seborrheic dermatitis, and PV and seborrheic dermatitis are fungal infections. However, cultures may be in of these and agents (eg, to the to support yeast dermatitis affects the chest, and and scaling are often and usually affects the with and to no A of inflammatory and a lack of scale usually 1 to 3 often in the and and presents with a by the of other often on the This is in to PV, in which have scale and are or of scale in and of the under Wood’s light from although rare, is the most common in children and presents as patches on the trunk and are often particularly in patients of and a is for diagnosis. is often when pityriasis or PV is is confirmed via microscopic examination with a positive Wood’s light examination may be clinically but not because not all species fluoresce yellow or should be from the of and the may be used if it is difficult to skin Under the species appear as and a of hyphae and yeast A clinical diagnosis should be confirmed before systemic treatment, but treatment can be that are effective and well with longer of treatment more likely to and are or for to 14 study ketoconazole shampoo response with for 3 selenium sulfide and ketoconazole shampoo are to affected areas for to minutes and in the sulfide may be more likely to of or selenium sulfide shampoo for 3 may antifungal agents include and treatment with antifungals should be considered in of or or if large areas are and fluconazole are but terbinafine is for In itraconazole for to days or fluconazole for 2 to 4 weeks is or treatment is common and or therapy may be ketoconazole should no longer be for in children or adults to of infection of the body where skin that a species, often However, candidiasis may also in of skin such as the and of the to with candidal diaper dermatitis, this not be few children present with infections in the and known as is most common than 1 and people with immune that the present species to estimated to of than 1 and about of children with develop an infection. include and use of and other Chronic mucocutaneous candidiasis (CMC) is and may a that is also with Patients with have or infections that can the and most common symptoms of are patches or on the or in the infected and at the of the is often more in the and differential diagnosis of MC on the of infection. If the has the differential diagnosis lichen and However, of these is found in childhood. For of or the differential diagnosis seborrheic dermatitis, dermatitis syphilis, and bacterial species in the are of the of species does not that there is an infection. diagnosis of MC is based on clinical However, the of species may be confirmed KOH microscopy or a culture. The of many the diagnosis of a candidal for candidiasis antifungals, either or systemic antifungal therapy is required for candidiasis and The recommendations are based on the most clinical by the of America. of candidiasis can be treated with or or should be treated with In if are than for more than 3 the may be to every until the less than For infections, itraconazole or is is when other treatment options candidiasis always be treated and fluconazole is For patients who complete fluconazole or an (eg, are with less For infections, or an may be used. In infections or therapy with fluconazole has been found to be Children who have infection also should be treated with highly therapy to infections. treatment is important because MC may lead to a more infection.