Demodex infestation in benign and malignant skin tumors

Abstract

Demodex mites are ectoparasites living in hair follicles, which results in inflammatory reactions. This mite has been detected in melanocytic nevi, actinic keratosis, melanoma, basal cell carcinoma, and lymphoproliferative tumors. Role of this parasite in skin tumors is unclear. This study aimed to only compare the frequency of mite infestation in benign and malignant lesions to propose the triggering effect of mites in skin tumors. This retrospective cross-sectional study was conducted on 602 skin biopsy samples with diagnoses of benign, premalignant, and malignant lesions over three years. Demodex infestation was evaluated according to sex, age, location, and histopathological diagnosis. A total of352 benign lesions and 250 malignant lesions were evaluated. There was a significant difference according to age, sex, location, and Demodex infestation rate between the benign and malignant groups (P<0.001). A total of 10.5% of the benign lesions and 23.6% of the malignant lesions were infested with Demodex mites (P<0.001). In the benign group, 38.5% of sebaceous nevi, 15.4% of vascular lesions, 13.8% of melanocytic nevi, and 11.6% of seborrheic keratoses showed mite infestation. In the malignant group, 55.6% of actinic keratosis, 27.3% of basosquamous cell carcinoma, 25.2% of basal cell carcinoma, and 14.6% of squamous cell carcinoma lesions had mite infestation. Actinic keratosis was significantly more infested compared to malignant lesions (P<0.001). This study revealed a significant difference in the frequency of Demodex infestation between malignant and benign lesions, but it is not clear whether Demodex infestationoccurred first or skin tumors.