Sunday, 14 October 2012

Post-traumatic psoriasis

The first manifestation of psoriasis may occur at any age. Early-onset psoriasis (age <40 years old) accounts for 75% of patients with psoriasis. Late onset psoriasis (age >40 years old) accounts for 25% of patients. The course is unpredictable and the variations numerous. Its duration may vary from a few weeks to a whole lifetime.
Post-traumatic psoriasis is not uncommon in young, athletic men, who develop psoriasis initially at the site of injury. Psoriasis is one of several conditions in which various types of trauma may elicit the disease in previously uninvolved skin (Koebner reaction).  The Koebner reaction is thought to be more frequent in actively spreading, severe psoriasis. The reaction appears to be a marker for a subgroup of patients with a tendency to early onset and early relapse after various forms of therapy.

The Koebner reaction usually occurs 7–14 days after injury. It obeys an all-or-none rule in a given patient (that is if psoriasis occurs at one site of injury it does so at all sites of injury).  Clearing of existing psoriasis following injury has been observed and termed the reverse Koebner reaction. This reaction also obeys an all-or-none rule, and the Koebner and reverse Koebner reactions are mutually exclusive.

Post-traumatic psoriasis in a young, athletic man, who has developed psoriasis at the site of injury on the right shin. The rest of the physical examination was unrevealing.

Auspitz’s sign: removal of the thinned suprapapillary epidermis, by gentle scraping, reveals vascular bleeding points. It can be seen here in the lower half of the lesion.

Improvement after applying a combined formulation containing betamethasone diproponate 0.05% and calcipotriol  monohydrate 50 micrograms /g,  once daily for two weeks. Note that calcipotriol enhances the efficacy of PUVA and UVB phototherapy. As UVA partly inactivates calcipotriol and UVB is absorbed by calcipotriol, it is recommended that calcipotriol is not applied until after phototherapy sessions.  Calcipotriol used in combination with methotrexate enables lower cumulative doses of methotrexate to be used.

This page was last updated in November 2012.  

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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