Time and rate of sinus formation in pilonidal sinus disease.
BACKGROUND: and aims To elicit mechanisms and timing of sinus development, the role of age at onset of symptoms, symptomatic disease duration, and consecutive number of sinuses were investigated. MATERIALS AND METHODS: Analysis of 1,962 medical records of patients admitted for primary surgical pilonidal sinus treatment. RESULTS: Sinus number ranged from 1 to 16 (median 2), with chronic pilonidal disease showing more sinuses than acute disease (mean 2.6 vs 2.1 sinuses; p < 0.0001; Kolmogorov-Smirnov). Disease duration in chronic pilonidal disease was not linked to sinus formation (p = 0.98; Spearman). In acute pilonidal disease, duration was linked to the development of six sinuses per 1,000 symptomatic disease years (p = 0.0001; Spearman). A larger sinus number correlated with earlier onset of symptoms (p = 0.009; Spearman). CONCLUSION: Long-standing chronic disease does not produce sinus per se. As sinus does not substantially arise during the course of symptomatic disease, there must be a time before the start of symptomatic disease when the sinus originates. These findings suggest that sinus can only be acquired up to a certain age, even if occupational exposure continues.