Congenital Retrosigmoid Cholesteatoma: Case Series and Literature Review.

BACKGROUND: This study aimed to discuss 3 cases of congenital cholesteatoma located posterior to the sigmoid sinus, with no/minimal involvement of mastoid, and compare them with cases presented in the literature to better define this rare entity. METHODS: Retrospective chart analysis of 3 congenital cholesteatomas located posterior to the sigmoid sinus treated surgically in 2 skull-base centers and literature review. Though congenital cholesteatoma can arise outside the middle ear, only a few cases presenting in the retrosigmoid occipital bone have been described earlier. RESULTS: In all 3 patients, there was a delay in the presentation, as symptoms were nonspecific or lacking, leading in 1 case to severe complications. Computed tomography and magnetic resonance imaging, especially diffusion-weighted imaging scans, allowed accurate diagnosis and surgical planning. Surgery happened to be challenging due to the tight adherence of the cholesteatoma to the thinned dural surface. Complete excision was achieved in all the cases. CONCLUSION: Congenital cholesteatoma located posterior to the sigmoid sinus is a rare entity and is even more exceptional after a critical review of the literature. Complete excision is quintessential to prevent intradural extension or infection. The most important surgical issue is the management of the posterior fossa dura and the sigmoid sinus. We recommend meticulous dissection with slow peeling of the epithelial lining from the dura. Bipolar coagulation of the dura may help in avoiding recidivism. Moreover, cerebrospinal fluid (CSF) leak during dissection has to be avoided as long as possible, because the loss of tension of the already thinned dura makes its peeling particularly difficult.