Acute-onset diplopia from intracranial hypertension due to torcular herophili obstruction by an hemorrhagic intradiploic epidermoid cyst

BACKGROUND: Epidermoid cysts are benign slow-growing congenital lesions, constituting approximately 1% of all cranial tumors. Most of these lesions are located intradurally, while about 10–25% of them are located within the diploic spaces. Intradiploic epidermoid cysts are usually discovered incidentally and may remain asymptomatic for many years, but in rare instances, they may grow intracranially and produce brain compression. Sometimes, intradiploic epidermoid cysts may occlude the main cranial venous sinuses causing intracranial hypertension. CASE DESCRIPTION: We present the case of a 24-year-old male harboring a paramedian right occipital intradiploic cyst with erosion of both outer and inner bony tables, which occluded the torcular herophili producing a worsening symptomatology with acute-onset diplopia from right sixth cranial nerve palsy; the patient also presented bilateral papilledema, but only reported mild headache and dizziness. Neuroradiological studies evidentiated a lesion compatible with intradiploic epidermoid cyst with intralesional hemorrhagic component, overlying and almost completely occluding the torcular herophili. Considering the fast worsening of symptomatology and the evidence of intracranial hypertension, the patient was operated on immediately after completion of clinical and radiological assessment. The lesion was radically removed with almost immediate reversal of signs and symptoms. Histopathology confirmed the diagnosis of epidermoid cyst with intralesional hemorrhagic components. CONCLUSION: Intradiploic epidermoid cysts may cause intracranial hypertension by occlusion of main cranial venous sinuses; intralesional hemorrhage may act as precipitating factor in occlusion of the torcular herophili, producing rapidly worsening intracranial hypertension, which requires prompt surgical treatment to reverse symptomatology. Radical surgical resection is necessary to avoid recurrence.