The epidermoid cyst is the most common embryonal tumor in the cerebellopontine angle and the third most common tumor in this topography. Cerebellopontine angle epidermoid cysts are benign WHO grade I lesions typically treated through aggressive microneurosurgical resection. Squamous cell carcinoma is an uncommon, aggressive, and malignant tumor resulting from the malignant transformation of the epidermoid cyst. This chapter reviews the special characteristics of the pathology, pathophysiology, symptoms, natural history, treatment, outcome, and prognosis of epidermoid cysts and squamous cell carcinoma. Epidermoid cysts occupy the cisterns of the cerebellopontine angle and can extend into the supratentorial and spinal cisterns, so a detailed review of their anatomy is conducted. The cyst membrane contains the tumoral epithelial layer that generates the cyst’s contents and induces its expansion, and must be entirely removed during microneurosurgical removal. Cerebellopontine angle epidermoid cyst has a fair outcome, low recurrence rate, low mortality, and favorable outcomes. Regrowth is more probable when resection is subtotal and occurs over time. Furthermore, it increases the uncommon risk of malignant transformation. The prognosis of squamous cell carcinoma is poor.