Posterior fossa dermoid cyst

Many reports have mentioned the intradural posterior fossa and the midline as the preferential localization of these intracranial dermoid cyst ^{1) 2)}. In contrast, extradural dermoid cysts are a much rarer entity ^{3) 4)}.

The histopathological differentiation between posterior fossa teratoma and posterior fossa intracranial dermoid cyst is very valuable for ruling out the presence of immature/malignant or germinomatous components that would require further adjuvant therapies. Posterior fossa teratoma mimicking posterior fossa dermoid cyst has been described ⁵⁾.

Cerebellopontine angle dermoid cyst.

see Posterior fossa dermoid cyst and Klippel-Feil syndrome.

Some of these dermoid cysts can get infected with dermal colonizing bacteria and cause deeper suppurations ^{6) 7) 8)}.

Teegala presents two original cases of infected posterior fossa dermoid associated with congenital heart diseases (CHDs) that is very rare. The embryologic basis for this unique occurrence is reviewed, and a new hypothesis proposed. Two infants with CHD presented with infected midline posterior fossa dermoid. Excision of the dermoid cyst with the sinus tract was performed. Postoperative period was uneventful. Both the infants had undergone surgery for congenial heart disease a few months prior to the present clinical presentation with uneventful recovery. Infected posterior fossa dermoid cyst without a discharging sinus should prompt a thorough examination to detect CHD. Early diagnosis and timely management results in better outcome ⁹⁾.

Paik et al. present a ruptured dermoid cyst of the cavernous sinus extending into the posterior fossa. The patient was a 32-year-old female who complained occipital headache, blurred vision, and tinnitus over 4 years. Brain magnetic resonance (MR) imaging revealed an enhanced tumor in the right cavernous sinus extending into the right temporal base and the posterior fossa with findings of ruptured cyst. Surgical resection was performed, and pathological findings were confirmed to be a dermoid cyst. They report a second case with ruptured dermoid cyst of the cavernous sinus extending into the posterior fossa ¹⁰⁾.

A 49-year-old farmer had a 2-month history of occipital headaches, which were not suggestive of raised intracranial pressure. During the last month, he experienced loss of balance, frequent falls, anorexia and loss of weight. Magnetic resonance imaging (MRI) showed a huge mass from the tentorium to the foramen magnum with obliteration of the fourth ventricle; the lesion was well circumscribed. Marina et al. completely removed the tumor and postoperative MRI showed no residual tumor. Epidermoid tumors with enhancing mural nodule on MRI and with hyperattenuating lesion on CT are extremely rare. Dermoid cysts are never associated with edema and extremely rarely cause obstructive hydrocephalus. MRI investigations are mandatory to diagnose these cases. The best curative treatment is total removal of the lesion ¹¹⁾.