Thursday, 3 November 2011



The history is characteristic. This 22-year old patient with a common fungal infection was satisfied initially with the cream prescribed by another doctor. He stopped applying the cream, the eruption relapsed. Further applications brought renewed relief and the cycles were repeated. He developed few persistent nodules, which become insuppressible by the cream. Scaling was lost in the groins areas as shown (A), and bruise-like brownish discolouration was seen (A). Scaling (arrows) was still seen on the buttocks (B). From which site autoinfection can occur?

Two other patients with the same history and similar findings. 

Spread to the scrotum is common, but scaling is minimal and inflammation is inconspicuous against a background erythema. The penis is occasionally affected as shown above. 

An extension of infection from the groins to the buttocks is not uncommon as shown above.

Short and long answers are provided below as comments.


  1. Short answer:
    There are numerous cases of autoinfection from the foot to the groin.

  2. Long answer:
    There are numerous cases of autoinfection from the foot to the groin and control of foot ringworm can lead to fewer cases of tinea cruris. In cases contracted from sharing of towels and sports clothing, the foot skin may be normal. Three anthropophilic species, T. rubrum, T. mentagrophytes var. interdigitale and E. floccosum, are responsible for the vast majority of cases of foot ringworm. An average clinic sample would be: T. rubrum infections, 70%; T. mentagrophytes var. interdigitale infections, 15%; E. floccosum infections, less than 10%; mixed infections, 5%. Tinea pedis is commoner in adults than children, but may begin to occur in young children aged 6 or more. The mean age of onset was 15 years in one survey (Jones HE, Reinhardt JH, Rinaldi MG. A clinical, mycological and immunological survey of dermatophytes. Arch Dermatol 1973; 108: 61–8).

    Control of tinea pedis can lead to fewer cases of tinea cruris. Moreover, interdigital tinea pedis often provides breaks in the integrity of the epidermis through which bacteria such as Staphylococcus aureus or Group A Streptococcus can invade, causing skin or soft-tissue infection (cellulitis or lymphangitis). Lymphoedema increases the likelihood of cellulitis. Use of 40% urea cream as an adjunct to topical antifungal proved to be successful in the treatment of moccasin tinea pedis (note that stratum corneum is thick there, making it difficult for topical antifungal agents to penetrate). However, the systemic antifungals terbinafine or itraconazole are of great value in this type of tinea pedis and one of them is usually given.

    Diagnosis: Steroid-modified tinea (tinea incognito).

  3. Note that:

    1) In cases of steroid-modified tinea (tinea incognito) the examination of vellus hairs may be the EASIEST method of diagnosis as, although fungi such as T. rubrum rarely invade the hair shaft, they may colonize the hair follicle.

    2) Scrapings may be difficult to obtain in a
    patient who is currently applying a steroid cream as shown above. If the patient stops it for a few days an upsurge of inflammation with marked scaling often occurs, making clinical diagnosis easier and facilitating the taking of scrapings. In such samples, fungal mycelium is
    usually abundant.

    3) Scrapings taken while steroids are still being applied may show very few fungal elements, unless a fluorescent whitener (Blankophor) is used.


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Main Works of Reference List (The first eight are my top favourites)

  • British National Formulary
  • British National Formulary for Children
  • Guidelines (BAD - BASHH - BHIVA - Uroweb)
  • Oxford Handbook of Genitourinary Medicine, HIV, and Sexual Health
  • Oxford Handbook of Medical Dermatology
  • Rook's Textbook of Dermatology
  • Simple Skin Surgery
  • Weedon's Skin Pathology
  • A Concise Atlas of Dermatopathology (P Mckee)
  • Andrews' Diseases of the Skin
  • Andrology (Nieschlag E FRCP, Behre M and Nieschlag S)
  • Bailey and Love's Short Practice of Surgery
  • Davidson's Essentials of Medicine
  • Davidson's Principles and Practice of Medicine
  • Fitzpatrick's Colour Atlas and Synopsis of Clinical Dermatology (Klaus Wolff FRCP and Richard Allen Johnson)
  • Fitzpatrick’s Dermatology in General Medicine
  • Ganong's Review of Medical Physiology
  • Gray's Anatomy
  • Hamilton Bailey's Demonstrations of Physical Signs in Clinical Surgery
  • Hutchison's Clinical Methods
  • Lever's Histopathology of the Skin
  • Lever's Histopathology of the Skin (Atlas and Synopsis)
  • Macleod's Clinical Examination
  • Martindale: The Complete Drug Reference
  • Oxford Handbook of Clinical Examination and Practical Skills
  • Oxford Textbook of Medicine
  • Practical Dermatopathology (R Rapini)
  • Sexually Transmitted Diseases (Holmes K et al)
  • Statistics in Clinical Practice (D Coggon FRCP)
  • Stockley's Drug Interactions
  • Treatment of Skin Disease: Comprehensive Therapeutic Strategies
  • Yen & Jaffe's Reproductive Endocrinology