SPOT DIAGNOSIS

Tattoo TroubleLorne V Mitchell clinical fellow in dermatology 1, Dawn M Caruana locum consultant dermatologist 1,Grant Wylie consultant dermatologist 2

1Walton Building, Glasgow Royal Infirmary, Glasgow, UK; 2Queen Elizabeth University Hospital, Glasgow, UK

A patient presented to the dermatology department with a skineruption over a new tattoo site (fig 1). What is the name of thephenomenon in this picture, and what is the underlying skincondition?

Fig 1 A skin eruption over a new tattoo site on the rightforearm

Short answerThis patient has chronic plaque psoriasis. The development ofpsoriatic lesions over a new tattoo site is known as the Koebnerphenomenon.

DiscussionLocalised skin eruption after cutaneous injury, in this case thedevelopment of psoriasis over a recent tattoo site, is describedas the Koebner phenomenon.1 It was first recognised by HeinrichKoebner in 1876, and is synonymous with the isomorphicresponse. Koebner himself drew a picture, published in 1883,of psoriatic Koebnerisation over a tattoo.2

Other types of cutaneous trauma known to provoke the Koebnerphenomenon include: excoriation (scratching), sunburn, friction,pressure, lacerations, bites, and vaccinations.1 Around 25% ofpatients with psoriasis will experience Koebnerisation, and itis therefore beneficial to warn them of its existence.1

This patient has clear evidence of a psoriatic plaque over theextensor aspect of the elbow (fig 2). In cases where the diagnosisof psoriasis is not entirely clear, as well as looking for evidenceover areas of predilection such as the scalp, umbilicus, elbows,and knees, searching for Koebnerisation over trauma sites canprovide key clues.

Correspondence to LV Mitchell lorne.mitchell@nhs.net

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BMJ 2017;356:i6816 doi: 10.1136/bmj.i6816 (Published 2017-01-19 2017-01-19 2017-01-19) Page 1 of 2

Endgames

ENDGAMES

Fig 2 Koebnerisation of psoriasis over the tattoo associatedwith a typical psoriatic plaque on the elbow

Vitiligo, a disorder characterised by focal areas ofdepigmentation, and lichen planus, an inflammatory conditionfeaturing pruritic papules, also both commonly displayKoebnerisation. There are many other skin diseases in which itis reported.3

In psoriatic Koebnerisation, the latency period from skin injuryto disease is normally between 10 and 20 days, but can be upto two years.1 The pathogenic mechanisms are not fullyunderstood, however studies show an increased production of

cytokines, CD4 lymphocytes, and adhesion molecules followingepidermal and dermal injury.1-4 Patients are more at risk ofKoebneristation when their skin disease is flaring, during wintermonths, and at times of emotional stress.3 4 An area ofKoebnerisation is treated in the same way as the associated skindisease.4

Cosmetic tattoos are becoming increasingly popular—36% ofyoung adults in the United States have at least one.5 Other skinproblems that are induced by tattoos include infection, allergiccontact dermatitis, and photosensitising reactions.4

Learning pointsThe Koebner phenomenon describes an eruption over a localisedarea of previously normal skin following subjection to trauma,in a patient with associated skin disease. It is most commonlyseen in patients with psoriasis, vitiligo, and lichen planus, andtherefore its finding can assist you in the diagnosis of these skinconditions.

We have read and understood BMJ policy on declaration of interestsand declare we have no competing interests.Patient consent obtained.

1 Sagi L, Trau H. The Koebner phenomenon. Clin Dermatol 2011;356:231-6. doi:10.1016/j.clindermatol.2010.09.014 pmid:21396563.

2 Kuner N, Hartschuh W, Khan-Durani B. [Heinrich Köbner and the “isomorphicphenomenon”. History and review of the literature]. Hautarzt 2003;356:274-8. doi:10.1007/s00105-002-0470-5 pmid:12634998.

3 Camargo CM, Brotas AM, Ramos-e-Silva M, Carneiro S. Isomorphic phenomenon ofKoebner: facts and controversies. Clin Dermatol 2013;356:741-9. doi:10.1016/j.clindermatol.2013.05.012 pmid:24160280.

4 Bashir SJ, Chew A-L. Mechanical injury to the skin. In: Griffiths C, Barker J, Bleiker T, etal, eds. Rook’s Textbook of Dermatology. Ninth ed. West Sussex: Wiley 2016:123.11.

5 Pew Research Center. Tattooed Gen Nexters. Dec 9 2008. URL: http://www.pewresearch.org/daily-number/tattooed-gen-nexters/ date accessed: October 2016.

Published by the BMJ Publishing Group Limited. For permission to use (where not alreadygranted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions

For personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribe

BMJ 2017;356:i6816 doi: 10.1136/bmj.i6816 (Published 2017-01-19 2017-01-19 2017-01-19) Page 2 of 2

ENDGAMES

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