Cuantificación del demodex folliculorum mediante reacción en cadena de la polimerasa y su asociación con el carcinoma basocelular en el área periocular

Supervised by:
  1. Alberto Tenorio Abreu Director
  2. Carlos Ruiz Frutos Director

Defence university: Universidad de Huelva

Fecha de defensa: 12 March 2018

  1. Raúl Ortiz de Lejarazu Leonardo Chair
  2. Juan Gómez Salgado Secretary
  3. Ángel Vilches Arena Committee member

Type: Thesis


Infestation by Demodex folliculorum (DF) in different diseases of the periocular region was considered and the objective was to estimate if it was a risk factor in basal cell carcinoma (BCC). Method. An epidemiological study of cases and controls was carried out and a standardized method for detecting Demodex folliculorum DNA was prepared by real-time Polymerase Chain Reaction (PCR) in solid CBC tissue. Descriptive and inferential statistics, t-student, Shapiro-Wilk, Pearson's correlation and binary logistic regression were used, and the odds ratio, sensitivity and specificity were calculated, all at 95% confidence intervals. Results. In the pilot test DF was found in 50% of the samples, 57% among men and 40% in women. At the controls the mean density was 308.65 amplicons / 1,125 mg of solid tissue. Real-time PCR had specificity of 100%, and the detection limit was between 1-10 copies / μl. When we studied 115 biopsies, cases (n = 64) with BCC and controls (n = 51) with benign lesions, there were no differences in sex or age (p> 0.05). The most frequent histological variety of BCC was nodular (70.3%) and seborrheic keratosis among the controls (about 25%). In the cases DF was detected in 42.2%; in the controls in 19.6% (OR 2.99; 95% CI 1.27-7) and in the subgroup of nodular BCC of 51.1% (p <0.05). The DF density was 15.29 copies in controls, while in the CBC it was 90.10 copies and in the nodular subgroup it was 112.4 copies (p <0.01). No correlation was detected between the increase in age and the density of the infestation. By anatomical localization, the prevalence of FD was higher in the inner canine and lower eyelid compared to controls; however, there were no differences in the density of the infestation. According to binary logistic regression, only the presence or absence of DF has statistical significance and not density. Conclusions: Real-time PCR is effective for the diagnosis, determination of DF prevalence and density. In CBC there is a greater presence of DF and higher density, especially in the inner canthus and lower eyelid. An association between DF and CBC is verified, which positions it as a potential risk factor for it.