Unexpectedly, in a patient identified with sterile eosinophilic peritonitis, the peritoneal effluent was extremely rich in CCL18, with levels approximately 10-fold higher than those found in patients with IP and 50-fold more than those found in uninfected samples, whereas, effluent levels of IL-6, which were evaluated in the same samples for comparative purposes, were similar on day 1 in both the IP and EP samples. This evidence concerns the gene CCL18 and incontinentia pigmenti.