Temporal dermoid cyst with a partial dermal sinus tract.

BACKGROUND Cranial dermal sinuses are rare and occur most frequently in the posterior fossa and along the midline. Likewise, supratentorial dermoid cysts are very uncommon. METHOD We report a unique case of an adult female patient with both a supratentorial dermoid cyst and an incomplete dermal sinus tract. RESULTS The patient is a 31-year-old female, who presented with a new onset complex partial seizure. Neuroimaging and surgery revealed a right superior temporal dermoid cyst with an associated dermal sinus tract. Furthermore, the dermal sinus tract was incomplete and had no cutaneous manifestations. CONCLUSION We present a rare patient with an off midline supratentorial dermoid cyst associated with a uniquely incomplete cranial dermal sinus tract. The dermal sinus tract involved the bone, dura and intradural compartment, without involving the overlying skin. This represents a novel variant in the spectrum of cranial dermal sinus abnormalities.