CLINICAL Superficial fungal infections Tom Kovitwanichkanont, SUPERFICIAL FUNGAL INFECTIONS are caused pompholyx eczema.8 Recurrent tinea pedis Alvin H Chong by dermatophytes in the Microsporum, may be due to a reservoir of untreated Trichophyton and Epidermophyton genera.1 tinea in the nails. Dermatophytes live on keratin, which Background Tinea is a common fungal infection is found in skin, hair and nails. There is that can affect the skin, nails and hair. evidence that continuing migrations and Tinea infection has a variety of clinical mass tourism contribute to the changing manifestations and affects all age groups, epidemiological trends.2,3 Tinea infections ranging from tinea pedis in adults to are named according to the Latin term that tinea capitis in pre-pubertal children. designates the anatomic site of infection, Objective such as tinea capitis (scalp), tinea corporis This article provides an updated (body), tinea manuum (hand), tinea overview of the common clinical cruris (groin), tinea pedis (foot) and tinea manifestations and practical unguium (nail). approaches to the diagnosis and management of tinea infections. Discussion Clinical manifestations While tinea may be suspected on the Tinea pedis Figure 1. Interdigital tinea pedis: Erosion and basis of clinical grounds, it is important Tinea pedis, colloquially known as scales of the subdigital and interdigital skin of to be aware of the various conditions ‘athlete’s foot’, is the most common the foot considered in the differential diagnosis that may mimic tinea infections. Topical dermatophyte infection. Its prevalence 4 5 and systemic antifungal modalities are increases with age; it is rare in children. available and are selected on the basis Exposure to occlusive footwear, sweating of the subtypes and severity of tinea and communal spaces are predisposing infection. Untreated, tinea can cause factors of tinea pedis.6 The interdigital significant morbidity and predispose to subtype is the most common form of tinea complications, including cellulitis and ulcers on the feet and alopecia on pedis, which manifests as maceration or 7 the scalp. scales between toes (Figure 1). Another subtype is the chronic hyperkeratotic (moccasin-type) tinea pedis, which is characterised by chronic plantar erythema with scaling involving the lateral and plantar surfaces of the foot (Figure 2). The dorsal surface is usually spared in Figure 2. Moccasin-type or chronic hyperkeratotic tinea pedis: Erythema and this subtype. A less frequent presentation hyperkeratosis of the plantar/lateral aspects of tinea pedis is the vesiculobullous or of the foot; consider oral therapy for these inflammatory form, which may sometimes severe cases be difficult to clinically distinguish from 706 | AJGP VOL. 48, NO. 10, OCTOBER 2019 © The Royal Australian College of General Practitioners 2019 SUPERFICIAL FUNGAL INFECTIONS CLINICAL Tinea unguium (onychomycosis) opening and diffuse scalp scaling with can sometimes occur at the active edge. Tinea unguium, also known as subtle hair loss. A severe form of tinea Although tinea infection is common, it is onychomycosis, is a dermatophyte capitis is referred to as ‘kerion’, which important to consider many other causes infection of the nails. Onychomycosis is characterised by a tender plaque with of an annular rash as described in Table 2. is very common in the elderly with a pustules and crusting.11 If untreated, prevalence of up to 50% in people aged kerion may cause permanent scarring and Tinea incognito over 70 years.9 Nearly half of patients alopecia. Cervical lymphadenopathy is Tinea incognito is a term for a tinea with toenail onychomycosis were a common associated finding in patients infection that has been misdiagnosed found to have concomitant fungal skin with tinea capitis.12 and inappropriately treated with a topical infections, most commonly tinea pedis.7 corticosteroid or other immunosuppressive The most common clinical subtype is the Tinea corporis and tinea cruris agents. The clinical features may become distal lateral subungual onychomycosis Tinea corporis, commonly known as masked with attenuated scale and that appears as yellowish or brownish ringworm, refers to a dermatophyte erythema, as well as a less well-defined discolouration associated with onycholysis infection on the skin of sites other than border (Figure 6). The infection may also and subungual hyperkeratosis (Figure 3). face, hands, feet or groin. Tinea cruris be exacerbated as the dermatophytes The other common subtype is the white is also known as ‘jock itch’ and occurs invade the dermis or subcutaneous tissue superficial onychomycosis, which has in the groin fold and is more frequent causing deep-seated folliculitis, also the appearance of white spots on the nail in adult men.13 Tinea corporis most referred to as Majocchi’s granuloma.13 plate that can involve the entire nail if commonly occurs in children and young not treated. Onychomycosis has many adults. Tinea corporis (Figure 4) and mimics (Table 1), so it is important to tinea cruris (Figure 5) classically present Practical approach to diagnosis establish a mycological diagnosis before as annular plaques with central clearing A diagnosis of tinea infection may commencing therapy. Individuals with and leading scale. The lesions may be be suspected on the basis of clinical underlying nail disease are at increased single or multiple and of varying sizes, history and examination. Since many risk of concomitant onychomycosis. which may coalesce. Pustules or vesicles conditions can mimic tinea infections, Immunocompromised and diabetic hosts are not only at a greater risk of onychomycosis but are also more Table 1. Differential diagnosis of onychomycosis33–37 susceptible to the bacterial complications Differential diagnosis Clinical features of onychomycosis, such as cellulitis. Nail psoriasis • Shares many common clinical and histopathological features Tinea capitis with onychomycosis Tinea capitis is a dermatophyte infection • Fingernails are usually more affected by psoriasis than tinea of the scalp and hair and it predominantly • Nail pitting is the most common sign of nail psoriasis and rare occurs in pre-pubertal children.10 The in onychomycosis three main clinical presentations of tinea • Nail bed ‘oil drops’: pink discolouration in the nailbed due to nailbed inflammation capitis are scaly patches with alopecia, • Other psoriatic skin changes alopecia with black dots at the follicular • Family history of psoriasis • Can coexist with onychomycosis in 20% of people with psoriasis Lichen planus • Typically affects several or most nails • Other cutaneous features of lichen planus • Pterygium unguis: Scarring between nail matrix and proximal nailfold • Nail plate thinning and longitudinal ridging Yellow nail syndrome • Association with bronchiectasis, chronic sinusitis and lymphoedema Traumatic • Usually only single nail affected onychodystrophy • Distal onycholysis Alopecia areata • Red-spotted lunula Figure 3. Distal lateral subungual • Regularly distributed nail pitting onychomycosis: The most common subtype of onychomycosis Age-related nail • Onychauxis and onychoclavus can be clinically identical to dystrophies onychomycosis © The Royal Australian College of General Practitioners 2019 AJGP VOL. 48, NO. 10, OCTOBER 2019 | 707 CLINICAL SUPERFICIAL FUNGAL INFECTIONS it is recommended that investigations false-negative rate of at least 30% for are performed to confirm the diagnosis. nail samples.17 Repeat culture should Although minor localised infections may be performed if there is a high index of be treated with empirical topical therapy, clinical suspicion. testing should be performed prior to commencing systemic therapy. Without the Advice on specimen collection diagnostic confirmation, prescribers may • Prior topical antifungal therapy may not know when to stop the therapy. lead to false-negative culture results. In recurrent cases of tinea, it is • Topical corticosteroid cream generally essential to identify any potential does not affect the isolation of reservoir for dermatophytosis. Toenails dermatophytes but it can make it are a common reservoir for tinea and can difficult to collect sufficient specimen. result in recurrent tinea pedis as well as The cream should be wiped off prior to transmission by autoinoculation to other scraping. body parts, such as the hand and groin.14,15 • Each site needs to be collected in As it is common for dermatophytes separately labelled containers to to concurrently affect more than one allow correct identification of the Figure 4. Tinea corporis of the neck: Classic body part at the same time, a full skin infective sites. annular erythematous plaque with leading scale examination should be performed to • Collect as much specimen as possible determine the extent of involvement and to maximise the yield. potential reservoir. In addition, animals • For skin scrapings: may also be reservoirs. Microsporum – Use a scalpel blade, held at an angle. canis is the most common dermatophyte – Always sample from the active isolate in tinea capitis, with cats and dogs leading edge of the lesion. Fungi recognised as important natural hosts.16 In are rarely identified from the these cases, animals should be tested and interdigital macerated samples treated until mycological cure, to prevent or the centre of the lesion. The reinfection in humans. moist interdigital areas of the feet are usually colonised with Diagnostic tests concomitant bacterial isolates, such Tinea infection can be diagnosed