Spectrum of Hybrid Cysts and Their Clinical Significance

A hybrid cyst is a cutaneous cyst combining different types of keratinization of those seen in the folliculo-sebaceous-apocrine unit. Previous reports found that it may be occasionally associated with Gardner syndrome. This study aimed to clarify the pathologic findings and clinical significance of hybrid cyst based on case series observations. We retrospectively reviewed patients who fulfilled the pathological criteria of hybrid cyst from 2001 to 2015. The patient profiles, clinical presentations, pathological findings, and associated diseases were analyzed by reviewing the medical records and slides. A total of 71 hybrid cysts were confirmed over the study period. There were 12 pathologic variants. The most frequent variant was combined infundibular cyst and tricholemmal cyst (22 in 71 cases, 30%), followed by infundibular cyst and pilomatricoma (14 in 71 cases, 19%). There was no significant association between sex, age, or site and the pathological type of hybrid cyst. Neither extra-intestinal manifestation nor a family history of Gardner syndrome was found in any case. Hybrid cysts could contain a variety of combinations of components from the folliculo-sebaceous-apocrine unit. No clinical significance was found between demographics and the type of hybrid cyst. No association with Gardner syndrome was identified in this case series.