PMC7749940_01
Preoperative (a) T2 magnetic resonance imaging (MRI), (b) diffusion-weighted imaging (DWI) MRI, and (c) magnetic resonance venography demonstrating right posterior fossa mass causing transverse sigmoid sinus occlusion with cerebellar distortion. (d) Postoperative DWI MRI showing resection of the mass.
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F1
Brain magnetic resonance imaging (MRI) revealed a 3 cm, extra-axial, diffusion restricting, posterior fossa mass involving the right temporal bone posterior to the mastoid air cells, invading and occluding the transverse/sigmoid sinuses, and distorting the cerebellum [Figure 1] Surgery was recommended for the goals of pathological diagnosis and maximal safe resection.
Histopathologic image demonstrating epidermoid tumor cyst wall with acellular keratin debris. The cyst is lined by keratinizing stratified squamous epithelium with a granular layer.
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F2
This was most consistent with an epidermal inclusion cyst with dystrophic calcification [Figure 2].