An eleven- year -old boy presented with erythematous lesion over the left post auricular region for one day. There was history of an insect seen over the area of rash on previous night. On examination, he was afebrile and had erythematous rash with vesicles over the posterior aspect of the left auricle and mastoid area (Fig. 1). The findings of systemic examinations were normal. His complete blood count was within normal limits. Based on the history, presence of typical kissing lesions a diagnosis of paederus dermatitis was made. The child was treated with topical steroid ointment. Skin lesions healed completely within one week.

Fig.1 Vesicles over auricle.

Paederus beetles have been associated with outbreak of dermatitis in various countries. Adult of these beetles are usually 7-10 mm long and 0.5 mm wide. They have black head and red thorax. Dermatitis is caused by paederine which is released on crushing the insect on the skin. The rash appears 24 hours after contact. A striking feature is the presence of kissing lesions that occur wherever apposition of skin is possible (e.g. flexure of the elbow, adjacent surfaces of the thigh). Clinical appearance of paederus dermatitis may be confused with herpes zoster, acute allergic contact dermatitis, liquid burns, millipede dermatitis and phytophoto dermatitis. There are many similarities between paederus dermatitis and phytophoto dermatitis including linear asymmetric areas of erthyema, possible blister formation and dyspigmentation. With phytophoto dermatitis, there is a history of exposure to light sensitizing biological substance such as lime or fig. The characteristic linear appearance of the lesion, the presence of kissing lesions and their predilection for exposed areas differentiate paederus dermatitis from other above mentioned conditions. Histopathology may support the diagnosis of paederus dermatitis. The cases should be managed with initial washing the area with soap and water followed by topical steroid ointment.