History

Fact Explanation
Scaly, itchy area of the inter-digital spaces and soles of feet Tinea pedis(TP) is caused by infection of the feet by dermatophytes such as: Trichophyton,Microsporum,Epidermophyton.[1,2] Itch and inflammation are caused by fungal metabolic products and a resultant delayed hypersensitivity reaction. [2] Dermatophyte infections are usually limited to the keratinized tissue of the stratum corneum and[2] scaling occurs due to increased proliferation of epidermal cells. TP is the commonest primary site of infection because, bare feet are frequently in contact with soil where geophilic sub types are found. Adolescents are the most commonly affected. [6]
Episodic vesiculobullous lesions Caused by T.mentagrophytes var. interdigitale, commonly affects sites such as the arch or side of the foot . Dermatophytid reaction(inflammatory reaction at distant site) can also be seen in the affected area.[5],[6]
Ulcerations Caused by T. mentagrophytes var. interdigitale, initially it occurs in the two lateral interdigital spaces and eventually extends to the lateral dorsum and the plantar surface of the foot. The lesions of interdigital spaces get macerated and develop scaly borders. Secondary bacterial infection can be superimposed on this lesions. [5]
People with immuno-supressions Immuno suppressed individuals i.e. patients with HIV/AIDS, long term steroid users or patients with diabetes mellitus[4] have a higher chance of acquiring TP. Delayed type-4 hypersensitivity and the activation of the T-cell mechanism are altered in these conditions.[3]
Occupational History Occupations at risk of TP are farm workers in contact with soil, zookeepers or veterinarians exposed to zoonotic dermatophytes.[4] In addition soldiers and athletes are at risk due to wearing shoes for a long duration which leads to increased moisture[3] that thereby promotes growth of dermatophytes, in addition to higher recurrence rates
Contact history Tinea pedis can be acquired by sharing showers[1],[2],[6] or swimming pools with infected patients as healthy skin comes into contact with keratin debris of the infected individual. [1],[6]
Reccurance Spores in occlusive footwear[2],[6] can lead to a recurrence, because fungal spores are the mode of spread for the dermatophytes.
Other sites/Types of Tinea infection. Tinea pedis is the commonest primary source for other types of tinea infections. For example T.cruris occurs in the groin with an itchy erythematous scaly plaque. [1],[2] T.unguium causes yellow colored,brittle nails. [1],[2] T.corporis occurs in the torso and causes an itchy erythematous scaly plaque with raised margins.[1],[2] T.manuum presents with well demarcated lesions on the dorsum of the hand and also causes erythematous, scaly lesions on palms.[1],[2]
Dry skin People with dry skin due to atopy related dermatological conditions tend to develop chronic Tinea infections.[3]
References
  1. BROWN Robin Graham, BURNS Tony. Dermatology Lecture Notes.10th ed.Sussex. Wiley Blackwell. 2011. Pg30-35
  2. WELLER Richard et al. Clinical Dermatology. 4th ed. Oxford. Wiley Blackwell. 2008. Pg248-252.
  3. QADIM Hamideh Herizchi. Factors leading to dermatophytosis. Annals of Parasitology. 2013. vol59(2), pg99–102
  4. Drake LA et al. Guidelines of Care for Superficial Mycotic Infections of the Skin:tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. Guidelines/Outcomes Committee-American Academy of Dermatology J Am Acad Dermatol. 1996;34:282–286
  5. HO, King-man. CHENG, Tin-sik. Common Superficial Fungal Infections –a Short Review. Medical bulletin. The Hong Kong Medical Diary [Online]. November 2010. vol.15. pg23-24 [viewed 16 April 2014]. Available from: http://www.fmshk.org/database/articles/04mb5_4.pdf
  6. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary

Examination

Fact Explanation
Interdigital scaling,cracks( usually 3-4 or 4-5) or diffuse scaling of soles Dermatophyte infections are usually limited to the keratinized tissue such as stratum corneum[2]. Scaling occurs due to increased proliferation of epidermal cells due to the reaction. Cracked, or macerated interdigital spaces can also be observed.[4]
Vesiculobullous lesions Caused by T.mentagrophytes var. interdigitale common sites are the arch or side of the feet . Dermatophytid reaction an inflammatory reaction at distant site can also be seen. [3],[4]
Ulcerations Caused by T. mentagrophytes var. interdigitale initially it occurs in the two lateral interdigital spaces and eventually extending to the lateral dorsum and the plantar surface of the foot. The lesions of interdigital spaces get macerated and develop scaly borders with superadded bacterial infection. [3]
Other sites of Tinea infections T.Pedis is the commonest primary source for other types of Tinea infections such as: T.Cruris which occurs in the groin, T.unguium that causes yellow, brittle nails, T.Corporis which occurs in the torso and T.manuum that causes lesions on the dorsum of the hand.[1],[2]
References
  1. BROWN Robin Graham, BURNS Tony. Dermatology Lecture Notes.10th ed.Sussex. Wiley Blackwell. 2011. Pg30-35
  2. WELLER Richard et al. Clinical Dermatology. 4th ed. Oxford. Wiley Blackwell. 2008. Pg248-252.
  3. HO, King-man. CHENG, Tin-sik. Common Superficial Fungal Infections –a Short Review. Medical bulletin. The Hong Kong Medical Diary [Online]. November 2010. vol.15. pg23-24 [viewed 16 April 2014]. Available from: http://www.fmshk.org/database/articles/04mb5_4.pdf
  4. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary

Differential Diagnoses

Fact Explanation
Contact irritant or allergic dermatitis Itching, erythema, papules and vesicles can be observed in the acute stage but in the chronic stages there is scaling and lichenification. Eczema is symmetrical in distribution[1] and usually spares the intertriginous areas. [3] Scratching can leave marks and give rise to secondary bacterial infection. The cause may vary (exogenous irritants or endogenous atopy).[1],[2]
Plantar keratosis This is a differential diagnosis to moccasin-type T.pedis[3]. This involves thickening of skin due to abnormal keratinization.Punctate type keratodermas result in tiny bumps on the palms and soles. This is usually non-transgradient however rarely it can become transgradient.
Plantar pustular psoriasis This is a differential diagnosis to the vesicobullous type T.pedis.[3] There is inflammation accompanied by pain and multiple pustule of 1-2mm in diameter. Brown macules or scaling occurs. [2]
Erythrasma This is due to Diptheroids that produce porphyrins. It is usually an asymptomatic that may cause wrinkling,scaling and macerated white areas of the skin. Common sites are under the arm pits, groins or in the interdigital spaces.[2]
Interdidital intertrigo This is a differential diagnosis for T.pedis.[2] This occurs between opposing skin surfaces. Maceration and secondary infections( commonly by Candida) is present. Whitish satellite pustules can be observed. There will be a characteristic scalloped edge. [1]
References
  1. BROWN Robin Graham, BURNS Tony. Dermatology Lecture Notes.10th ed.Sussex. Wiley Blackwell. 2011. Pg30-35
  2. WELLER Richard et al. Clinical Dermatology. 4th ed. Oxford. Wiley Blackwell. 2008. Pg248-252.
  3. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary

Investigations - for Diagnosis

Fact Explanation
Microscopy of scrapings Scales, roof of the vesicle or the purulent debris of a pustule are sampled. The specimen is kept on a glass slide and 10% to 15% KOH is added [1], the KOH dissolves the epithelial tissue, allowing microscopic visualisation of the hyphae. Light microscopy shows septate hyphae, which is diagnostic.[1],[2] Indicated if the diagnosis is unclear, or if there is a poor response to topical treatment prior to prescribing oral anti fungals.[3]
Cultures The culture medium used is Sabouraud’s glucose agar. The addition of an antibiotic, inhibits bacterial overgrowth.Indicators that are added produce a color change. It may take days to get a positive report Therefore this investigation is not widely used. [1],[2] Indicated if the diagnosis is unclear, or if there is a poor response to topical treatment prior to prescribing oral anti fungals. [3]
Wood's light examination Though this is not helpful in diagnosing T.pedis it helps to exclude other potential differential diagnoses such as erythrasma which produces a coral red color under ultraviolet light. [3]
Bacterial culture Done to identify super added bacterial infections. [1]
Skin biopsy Requested for differentiation of a dermatophyte infection from other dermatoses. [1]
References
  1. Drake LA et al. Guidelines of Care for Superficial Mycotic Infections of the Skin:tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. Guidelines/Outcomes Committee-American Academy of Dermatology J Am Acad Dermatol. 1996;34:282–286
  2. WELLER Richard et al. Clinical Dermatology. 4th ed. Oxford. Wiley Blackwell. 2008. Pg248-252.
  3. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary

Management - General Measures

Fact Explanation
Patient education Inform the patient that the symptoms are caused by a fungal infection and it is treatable. Emphasize the importance of hygiene to prevent transmission and reduce recurrence. [1]
Use of modified footwear and encourage usage different pairs of shoes Encourage patients to wear footwear that keeps the feet cool and dry, in order to prevent build up of moisture inside the shoe as this increases the fungal growth. [1]
Encourage use of cotton socks Cotton keeps moisture way from the surface of the skin.[2]
Dry feet and interdigital spaces after washing Reduction in moisture will reduce the fungal growth.[2]
Actions to prevent transmission Inform the patient to avoid scratching feet , because T.pedis is the commonest primary site of infection and scratching can spread the infection to other sites. Also inform patients to avoid walking barefoot in public places and not to share towels. [1],[2]
References
  1. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary
  2. WEINSTEIN Andrew, BERMAN Brian. Topical Treatment of Common Superficial Tinea Infections. Am Fam Physician [Online]. 2002 May 15;65(10):2095-2103. Available from: http://www.aafp.org/afp/2002/0515/p2095.html

Management - Specific Treatments

Fact Explanation
Topical application of clotrimazole, econazole or miconazole For mild, non-extensive disease topical antifungals are used[1],[3].Imiazoles are fungistatic in action. It inhibits the cytochrome p450 system[2]
Topical corticosteroids For lesions with marked inflammation, prescribe a mildly potent topical corticosteroid such as hydrocortisone 1%, in addition to the topical antifungal, for 7 days. For lesions in interdigital spaces a corticosteroid should be used once a day.[1]
Oral anti fungal treatment In a patient with an extensive infection[3] or poor response to topical treatment oral therapy should be initiated. Recommendation for oral drugs are: a positive microscopy or a positive culture/ clinically diagnosed with repeat sample.[1] Terbinafine is well tolerated and has a reduced side effect profile compared to other drugs.[1] This drug is fungicidal in action.It inhibits squalene epoxidase enzyme.[2] Itraconazole or griseofulvin are alternatives to terbinafine. Itraconazole is fungistatic in action. It inhibits the cytochrome p450 system.[2]
Treat other areas with Tinea infections Can be treated with topical nail preparations such as Amorolfine, Ciclopirox or Tioconazole in addition to the previously discussed topical anti fungals. [2]
References
  1. Fungal skin infection-foot. Clinical Knowledge Summaries. National Institute of Health and Care Excellence. 2013 [viewed 10 April 2014] Available from: http://cks.nice.org.uk/fungal-skin-infection-foot#!topicsummary
  2. WELLER Richard et al. Clinical Dermatology. 4th ed. Oxford. Wiley Blackwell. 2008. Pg248-252.
  3. BROWN Robin Graham, BURNS Tony. Dermatology Lecture Notes.10th ed.Sussex. Wiley Blackwell. 2011. Pg30-35