Case Report Trichilemmal cyst involving the skull base

Summary Background. Trichilemmal cyst (TC) a rare tumour originating from the outer root sheath of the hair follicle particularly in the scalp has never been reported to involve the skull base. Here a case of TC extensively involving the skull base is presented. The neuro-imaging, operative, and pathological features are described. Possible histogenesis is also discussed. Method. The clinical, radiological, operative, and pathological features of a TC involving the temporal-infratemporal fossae, orbit, paranasal sinuses, and the clivus is described. Findings. Multilocular cysts full of keratinized material were found. Histopathological findings were consistent with those for a typical cutaneous TC. Conclusion. TC of the variety found in the skin may involve the skull base extensively where it shows the typical histopathological features.