Skull base malignancy following long-term sinus mucocele and osteomyelitis. A case of skull base malignancy following long-term sinus mucocele is presented. While the similarity in clinical signs between sinus mucocele and malignancy has recently been emphasized in the literature, no previous case of skull base malignancy following frontoethmoid mucocele has been reported. The literature is reviewed and the association between inflammatory conditions and sinus malignancy is outlined. 