'Here comes the sun': pigmentary traits and sun habits in women with endometriosis

There is limited but interesting evidence suggesting that endometriosis may be associated with specific pigmentary traits and sun habits. In this case-control study, we aimed to further clarify this point. Consecutive patients with a first laparoscopic diagnosis of endometriosis according to Holt and Weiss criteria were selected as cases. Controls were women who underwent laparoscopy during the same study period, but who were found to be free of the disease. Selected women were interviewed and examined by two trained physicians. An unconditional logistic regression model that included age and baseline variables significantly differing between the two groups was used to estimate the adjusted odds ratios (OR). There were 98 women with endometriosis and 94 controls selected. Overall, women with the disease had a more photo-sensitive phenotype and were exposed less to sun or ultraviolet radiation. A statistically significant difference was documented for eye color, skin reaction to first sun exposure, freckles score and the use of tanning creams. The adjusted OR (95% CI) for the disease was 1.95 (1.02-3.72) for women with green/blue eyes, 2.19 (1.12-4.28) for those who frequently/always had skin burn reaction to first sun exposure, 5.67 (1.98-16.24) for those with a higher number of freckles and 0.35 (0.15-0.85) for the use of tanning creams. Women with endometriosis have a specific photo-sensitive phenotype and protect themselves more from the sun. This latter habit may be consequent to the former. We speculate that there is a shared genetic background between pigmentation and endometriosis.