5- and 10-Year Recurrence Rate Is the New Gold Standard in Pilonidal Sinus Surgery Benchmarking
retention, while others may seem silent. From histological evaluation of so-called incidental sinuses we know that every sinus is accompanied by acute, chronic or mixed acute-chronic tissue inflammation, even if it may seem clinically uninflamed [6] . Thus varying degrees of inflammation may bias the effects of treatment, wound healing and recurrence. Thirdly, from recent long-term examinations we know that recurrence rate is a function of time. Pilonidal sinus recurrences may occur from the time of surgery up to 22 years and beyond. Putting this into a time frame, 60% of all recurrences will be seen within 5 years [7] . This has been proven on more than 500 patients, who received long-term follow-up of 2 decades. It is therefore obvious that a very short-term follow-up will result in very low recurrence rate. As a benchmark, the 5and 10-year recurrence rate is the new gold standard. The authors of the presented study [8] enrolled 30 consecutive pilonidal sinus patients within 4 months for the study, which makes them a high-volume hospital in terms of pilonidal sinus surgery. They treated them with incision of tracts and the pilonidal cave, adding phenol liquid cauterization, dressing and 1 week’s daily follow-up to that therapy. They followed up patient satisfaction and if patients recommended their therapy to fellow patients. Some remarks need to be added to this small study with a 14-month mean follow-up time. Firstly, the results show Pilonidal sinus disease is a disease of young men that results in prolonged time off from work, its incidence being approximately 1 in 1,000. Now, 129 years after the first description of pilonidal sinus disease, there is a wide range of therapies and still controversy about the management of the condition. The only cure may be surgery, but every new conservative method needs to be thoroughly examined and compared with established methods in terms of aggressiveness and effectiveness. This is the case with phenol treatment of pilonidal sinus disease. First instituted in 1964 by Maurice and Greenwood [1] , they found a recurrence rate of 19% after 18 months of follow-up. Twenty-four studies using phenol have been published since then, with patient numbers up to 143, follow-up periods between 1 month [2] and 98 months [3] , and a recurrence rate between 9% [4] and 19% [5] . Recurrence rates vary widely and there are some explanations for this inconsistency. Firstly, pilonidal sinus disease is thought to be an acquired disease of hair interrupting the skin integrity, thus forming persisting epithelial tracts around hair. If tracts containing hair are only removed or destroyed partially, remnants will persist in the deeper layers of the skin, acting as a source of recurrent disease. Secondly, success and failure of pilonidal sinus therapy depend on the degree of inflammation of the pilonidal sinus, which is especially true for phenol treatment. Some sinuses present with overt inflammation and