Answer to last month's Clinical Quiz

Question:
This is a 40 years old driver who was admitted for investigation of a positive serological test for syphilis. Two hours after completion of lumbar puncture, while resting in hospital, the patient complained of an itchy and burning sensation over the skin rash as shown.

Answer:
C. Allergic contact dermatitis

This patient had a simple dressing at the lumbar puncture site after the procedure. Within hours, the patient complained of a burning and itchy sensation at the site of dressing. There was a well-demarcated erythematous rash at the site of dressing contact with the adhesive. The area covered and protected by cotton gauze was clear of rash when the site was examined after removal of dressing. It is an allergic reaction to the adhesive of the dressing. Exposure to adhesives and glues is common in daily living and household activities. Para-tertiary butylphenol formaldehyde resin (PTBP-FR), epoxy resin, acrylates and colophony rosin are common culprits identified by patch test for those who are suspected to suffer from adhesive and glues allergy. In this case, the condition can be confirmed after the rash has subsided completely by patch test. Patch test is an in-vivo test that can identify the allergen in a cell mediated hypersensitivity reaction and in this case, either colophony or acrylates would be found positive. History of contact allergy to adhesive tapes is essential for documentation because future avoidance of the allergens is the only way to avoid its relapse. Drug eruption in the form of morbilliform eruption never has this sparing involvement at the gauze-covered area. Secondary syphilis can mimic any rash but it is not itchy and usually appears less inflamed. Contact urticaria is an important differential. Latex in natural rubber can induce allergic contact urticaria that can present in different forms. Health professionals and children with spina bifida who have frequent contact with latex are at higher risk of developing the latex contact urticaria. It can present as severe systemic anaphylactic reaction within minutes after contact with the allergen but it can also present as widespread erythema, urticaria, rhinitis and conjunctivitis.