Paederus dermatitis in Egypt: a clinicopathological and ultrastructural study

Area of Science:

• Dermatology
• Toxicology
• Pathology

Background:

• Paederus dermatitis (PD) outbreaks are globally reported, but detailed histopathological and ultrastructural changes, especially concerning pederin toxin, remain underexplored.
• Understanding the cellular mechanisms of PD is crucial for effective management and potential therapeutic insights.

Purpose of the Study:

• To clinically characterize Paederus dermatitis (PD) presentations in Egypt.
• To investigate the effects of pederin toxin on skin by evaluating histopathological and ultrastructural changes in affected individuals.

Main Methods:

• Clinical and epidemiological data collected from 113 patients diagnosed with PD.
• Histopathological examination of skin biopsies from 40 patients.
• Ultrastructural analysis using electron microscopy (EM) on biopsies from 20 patients.

Main Results:

• Common clinical findings included erythematous plaques with micropustules; linear blisters and kissing lesions were also observed.
• Multiple lesions were frequent (78%), with the face being the most affected site (48%). The causative insect was identified as Paederus alfierii.
• Histopathology and EM confirmed acute irritant dermatitis in the upper epidermis and revealed apoptotic changes (chromatin condensation, DNA fragmentation) in the basal and suprabasal layers, attributed to pederin toxin.

Conclusions:

• This study provides the first comprehensive description of clinical, histopathological, and ultrastructural features of Paederus dermatitis (PD).
• The observed epidermal abnormalities are primarily due to the irritant effects of pederin toxin.
• The induction of apoptosis by pederin toxin in the lower epidermis warrants further research for potential applications in managing hyperproliferative disorders.