Adult nasal dermoid sinus cyst.

Nasal dermoid sinus cysts (NDSCs) are uncommon occurrences that require intervention usually because of complications with cyst expansion such as chemical meningitis, infection, and sequelae of mass effect such as new-onset seizures. Although many cysts are removed in childhood, some are not detected until adulthood. They become symptomatic and further evaluations illuminate an NDSC that has progressed. Most present as extracranial lesions in childhood and are effectively removed via open rhinoplasty with no recurrence; however, occasionally, they extend intracranially. This case report presents a unique (unusual) extension of the NDSC into the frontal sinus requiring an osteoplastic flap to access the frontal sinus floor combined with a local midline nasal incision at the sinus tract origin. A discussion of various clinical presentations and surgical approaches and a case report of a 35-year-old man are presented. This case adds to the growing amount of literature on NDSCs and demonstrates an unusual presentation, which has thus far not been documented.