Supra-and infratentorial epidermoid cyst with hydrocephalus due to occlusion in a 55-year-old man
cMRI sagittal T1 with contrast mediumcMRI coronar T1 with contrast mediumcMRI axial T1 with contrast mediumEpidermoid cysts are benign lesions lined by cornified epithelium containing lamellated keratin without calcifications. They lack the property of autonomous growth, they only grow because material accumulates in the cyst. If they increasize in size, their growth is linear, not exponential like in tumors. They can present ubiquitously and arise from scattered ectodermal cells. Cell scatter occurs during embryonic development, through disorders of cell migration or trauma on the epidermis by, for example, punctures. Aberrant germ cells, like in teratomas, can also be the cause of an epidermoid cyst.
The basis for formation of epidermoid cysts often develops prenatally. Usually middle aged patients develop symptoms due to the cyst blocking the draining of cerebrospinal fluid, leading to hydrocephalus. Occasionally they also cause trigeminal neuralgia by pressure on the trigeminal nerve in the cerebellar pontine angle. Cysts rarely rupture, but if it happens this can lead to aseptic meningitis. If a malignant transformation occurs, epidermoid cysts can also lead to squamous cell carcinomas.