Blister Beetle Dermatitis: Few Observations Helping in Diagnosis

DEAR EDITOR

Blister beetle dermatitis is an irritant contact dermatitis, caused when beetles of the genus Paederus are crushed on the skin, releasing the vesicant pederin.[1] It is also known as Dermatitis Linearis or Paedrous Dermatitis.[2] It is characterized by the presence of erythematous and edematous lesions, pain and burning sensation, blisters, pustules and kissing lesions.[1]

Though blister beetle dermatitis is a clinical diagnosis, at times it becomes difficult to identify it. Differential diagnosis of Blister beetle dermatitis include Herpes simplex, H zoster, allergic or irritant contact dermatitis, Bullous impetigo and phyto photo dermatitis. Authors have observed that in many cases of blister beetle dermatitis, even on mild touch over the affected area, patient will feel burning sensation and he will immediately pull back the touched body part. This sign may be named as “Pull back sign of Ashish”. This sign may be positive in few other conditions with localized hyperesthesia. It may be due to voluntary reaction due to hyperesthesia over inflamed area. This sign helps a lot in suspected cases of blister beetle dermatitis, where diagnosis is confusing. Authors would like to share one more observation that on touching a lesion of blister beetle dermatitis, many patients give a facial expression of pain/hyperesthesia. Many other similar conditions may not show this sign.

Although it is mentioned that signs of Blister beetle dermatitis appear after 24-48 h of contact, but practically, authors have noticed that most of the patients observe the lesions in the early morning after sleep.[2] Study by Padhi et al.[3] also reported the same observations. These few observations may be small, but helps a lot in diagnosing the cases of Blister beetle dermatitis.