A Rare Case of Coexistence between Epidermoid Cyst and Meningioma in Cerebellopontine Angle Manifesting as Trigeminal Neuralgia

Sir, Although meningioma and epidermoid cyst rank the top two common nonacoustic tumors of cerebellopontine angle (CPA),[1] their simultaneous occurrence is extremely scarce. We present such a rare case of concurrent meningioma and epidermoid cyst in CPA manifesting as trigeminal neuralgia, hence this letter to you.A 73-year-old woman, who had complained of recurrent and unbearable facial pain for 3 months, was admitted to our hospital. The patient experienced paroxysmal electric shock-like pain on the right side of her face, which was usually triggered by activities such as facial cleansing, tooth brushing, speaking, swallowing, and chewing. On examination, the patient had no positive physical findings, except for the only observed neurological anomaly, a decrease in temperature, touch, and pain perception on the right side of the face. Enhanced cranial magnetic resonance imaging (MRI) revealed a suborbicular lesion measuring 24 mm × 17 mm in the right CPA, characterized by well-defined margins and a broad base, demonstrating low signal intensity on T1-weighted MRI, high signal intensity on T2-weighted MRI, and significantly homogeneous enhancement with the presence of a meningeal tail sign at its periphery. Additionally, an irregular lesion measuring 37 mm × 12 mm in maximum cross-section was observed in the prepontine cistern and bilateral CPA cistern. This lesion exhibited low signal intensity on T1WI, high signal intensity on T2WI, and DWI without evident enhancement. Notably, the right trigeminal nerve passing through these lesions demonstrated clear local compression [Figure 1].Figure 1: (a-h) Cranial MRI before and after operation. (f) The right trigeminal nerve (white arrow pointed) apparently compressed by a substantial lesion rather than vessels in REZ. (g and h) Head MRI performed 2.5 years after surgery confirmed the meningioma (yellow arrowhead pointed) and the most right portion of epidermoid cyst had been removed. Pathological diagnosis of Epidermoid Cyst (l) and meningioma (i-k) was made. Abundant cells and typical intranuclear pseudoinclusions showed in HE staining (i). (jand k) Expression of progesterone receptor (PR) (j) and epithelial membrane antigen (EMA) (k), verified in immunohistochemical staining. The cheese-like fragments present eosinophilic fibers under microscope (l)After routine preparation, the patient underwent endoscopic resection via a right retrosigmoid approach with the assistance of pneumatic arm. During the operation, a complete resection was performed on the soft yellow tumor with a wide base attached to the petrous bone. Subsequent examination revealed clear compression and traction of the trigeminal nerve caused by another white caseous tumor with a pearly luster located in the root exit zone (REZ). Most of the right tumors were gradually excised, leading to adequate decompression of the trigeminal nerve. The definitive pathological diagnosis of the surgical specimen confirmed meningioma [Figure 1i-k], classified as WHO grade I, along with epidermoid cyst [Figure 1l]. The patient exhibited a favorable postoperative recovery, with no recurrence of symptoms observed throughout the 3.4-year follow-up period. Pure endoscopic surgery provides a broad and closed high-definition visual field,[2] facilitating more radical resections and shorter surgical durations, thereby tremendously promoting the realization of minimally invasive ideal by “one hole for all lesions”. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.