Contact allergy is unlikely to mimic basal cell carcinoma
BMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7182.538 (Published 20 February 1999) Cite this as: BMJ 1999;318:538
- Fiona M Chapman, Visiting oculoplastic fellow (A3465694{at}infotrade.co.uk),
- Brian Leatherbarrow, Consultant ophthalmologist, oculoplastic and orbital surgeon,
- Michael H Beck, Consultant dermatologist,
- Nicholas R Telfer, Consultant dermatologist
- Manchester Royal Eye Hospital, Manchester M13 9WH
- Contact Dermatitis Investigation Unit, Dermatology Centre, Hope Hospital, Manchester M6 8HD
- Mohs Micrographic Surgery Unit, Dermatology Centre, Hope Hospital
EDITOR—Hogg reported a textbook example of a basal cell carcinoma in which biopsy was non-diagnostic.1 The lesion apparently resolved after potent topical steroids were given based on a diagnosis of “sensitivity to PPD, a component of hair dye.”
We regularly deal with both periorbital tumours and allergic contact dermatitis and would advise caution about accepting the conclusions of this case at face value. Firstly, both the clinical appearances and the possibility of a false negative biopsy result (sampling error) make us suspicious of the claim that the lesion was completely benign. It is wise to repeat a biopsy when the result is not compatible with the clinical picture. Secondly, apparent resolution of the lesion after topical steroids have been given does not exclude the diagnosis of basal cell carcinoma, which is known to wax and wane.
Thirdly, contact allergy to PPD in hair dye typically results in eczematous changes at the scalp margin and periorbital skin bilaterally. It does not usually cause a solitary skin lesion. In this case the contact allergy to PPD found by patch testing is likely to be coincidental. Positive patch test results should be considered relevant only if they are compatible with the clinical picture.
We hope that this case will not result in any reduction of clinical vigilance. Significant delay in the diagnosis of skin cancer in this anatomical site may result in the progressive destruction of tissues, which complicates both complete removal and reconstruction.