“…This complication is uncommon: since 1958 only 52 cases have been published, most often as case reports – 27 cases were reported in a review in 1995 [15], which omitted 3 additional ones reported up to that time period [16,17,18], 22 additional cases were then published from 1995 to 2008 [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. Lapins et al [37] reported 5 cases of ‘nonmelanoma skin cancer’ among a cohort that may contain some patients who did not have criteria for HS so we did not include those results.…”