Intracranial squamous cell carcinoma of the cerebello-pontine angle mimicking a cystic acoustic schwannoma. A case report with discussion of differential diagnosis and review of literature

Primary intracranial squamous cell carcinoma in a mule

Primary intracranial squamous cell carcinoma is a malignant neoplasm reported only in humans and usually originates from epidermoid or dermoid cysts. We describe the first case of primary intracranial squamous cell carcinoma in an animal, emphasizing its clinical, pathological and immunohistochemical findings. A 15-year-old male mule was euthanized after bilateral blindness. At necropsy, the optic nerve, optic chiasm, pituitary gland and trigeminal nerve were surrounded by a multilobulated, firm, whitish mass interspersed by yellowish, irregular, friable multifocal areas of cavitation. Histologically, the mass was formed of neoplastic pleomorphic squamous epithelial cells that formed nests and sometimes contained areas with keratin pearls. Neoplastic cells were immunopositive for cytokeratin and immunonegative for vimentin and alpha fetoprotein. We conclude that primary intracranial squamous cell carcinoma can occur in animals and result in neurological signs, and should be considered as a differential diagnosis for diseases of the central nervous system.

The imaging dynamic changes in the malignant transformation of an epidermoid cyst: a case report and literature review

Malignant transformation of epidermoid cysts is a rare complication. Most of the previously reported cases have involved postoperative malignant transformations. We present a case of malignant transformation of a nonpostoperative epidermoid tumor into squamous cell carcinoma (SCC) that occurred in a 61-year-old Chinese woman. The patient's initial cranial MRI scan showed an epidermoid cyst with marginal enhancement in the pre-pontine cistern, and the lesion gradually enlarged after 10 months. A craniotomy was performed using to remove part of the tumor via the right retrosigmoid approach, and postoperative pathology confirmed that the transformation of the epidermoid cyst was malignant. Our case study suggests that the possibility of malignant transformation of epidermoid cyst should not be ignored on the basis of enhanced imaging features, regardless of whether they are nodular, annular, or patchy, as is the case for inflammation. Strict follow-up is required for early detection of malignant transformation to prompt correspondingly early clinical treatment.