Primary Intracranial Squamous Cell Carcinoma in the Brain Stem with a Cerebellopontine Angle Epidermoid Cyst

Primary intracranial squamous cell carcinoma is extremely rare, with most cases arising from a preexisting benign epidermoid cyst. We report a rare case of primary intracranial squamous cell carcinoma in the brain stem with a cerebellopontine angle (CPA) epidermoid cyst. A 72-year-old female suffered from progressive left hemiparesis, difficulty in swallowing, and right hemifacial numbness. Diffusion-weighted magnetic resonance imaging revealed a high signal intensity (SI) lesion in the CPA region and an intra-axially ring-enhanced cystic mass in the right brain stem with low SI. Whole-body positron emission tomography showed no evidence of metastatic disease. The histological findings revealed a typical epidermoid cyst in the CPA region and a squamous cell carcinoma in the brain stem. We speculate that the squamous cell carcinoma may have been developed due to a chronic inflammatory response by the adjacent epidermoid cyst. The patient underwent a surgical resection and radiotherapy. After 12 months, she had no evidence of recurrence.     

Giant intradiploic epidermoid cyst of the occipital bone

Epidermoid cysts are uncommon, benign and slow-growing lesions. They often reach an enormous size without producing neurologic symptoms. We describe a 35-year-old female who had a giant intradiploic epidermoid cyst of the occipital bone. She underwent posterior cranial fossa tumor resection. Pathology confirmed epidermoid cyst. There was no recurrence at 13-month follow-up. Total removal of these cysts and repeated washing of the cavity with 0.9% saline may prevent recurrence and aseptic meningitis.     

Intracranial germinoma in the pineal region arising after subtotal resection of epidermoid cyst: case report

We present an unusual case of a germinoma of the pineal region arising adjacent to an epidermoid cyst in a 16-year-old male. Initial imaging findings were classic for epidermoid cyst. The patient underwent two partial resections at an outside institution, each specimen demonstrating pure epidermoid cyst. Follow-up imaging over a period of 24 months showed an area of progressive contrast enhancement adjacent to the initial lesion, suggesting the development of a neoplasm. Given the area of contrast enhancement in addition to worsening headaches and visual changes, he underwent a third and final resection at our institution. Pathology revealed a mixed germ cell tumor with prominent germinoma component in addition to a well-differentiated epidermoid cyst. Details of his imaging and pathologic findings are presented, and possible explanations for these findings are explored, the most likely of which is lack of complete resection at the onset failed to identify the whole of the neoplasm. We conclude that pediatric epidermoid cysts of the pineal region should always receive close follow-up, particularly when total resection is not performed.     

Spontaneously hyperdense intracranial epidermoid cyst

Intracranial epidermoid cysts are relatively rare tumors. These cysts are generally nearly isodense to CSF at CT and nearly isointense to CSF on T1W and T2W MR imaging. Spontaneously hyperdense epidermoid cysts are exceptional. We report the case of a 12-year-old girl with a spontaneously hyperdense epidermoid cyst of the posterior fossa presenting with focal neurological symptoms. The diagnosis was confirmed at histological examination.     

Intracranial epidermoid cyst with proliferative folliculosebaceous epithelium: Report of a rare case and discussion on pathogenesis

Intracranial epidermoid cysts are rarely known to increase in size over a brief period. While malignant transformations of epidermoid cyst have been previously described, no reports to date have described rapid proliferation accompanied by mature hair follicles and sebaceous glands without malignant transformations. The present case involved a 71‐year‐old man who visited a local physician with disturbance of equilibrium. A mass lesion was detected at the left cerebellopontine angle and was subsequently removed. Histopathological diagnosis of this lesion was as an epidermoid cyst. Seventeen years after this initial surgery, worsened left hypoacusis, disorientation, eating disorder and gait disturbance appeared, and the patient visited the physician again. Local recurrence of the lesion was observed, and the patient was referred to our hospital for its removal. Intraoperative findings revealed a pearly white tumor, histopathologically diagnosed as an epidermoid cyst. Three years later, local recurrence was observed, and the cyst was again removed. Intraoperative findings revealed a partially pearly white tumor similar to the tumor observed during the second surgery, but the majority of the tumor was non‐shiny, ochre‐colored and suckable. Histopathological diagnosis was an epidermoid cyst with an epidermis‐like structure. Postoperative activities of daily living were independent thereafter, but from March of the following year, he began to experience increasing difficulty in walking and subsequently visited our hospital again. Tumor recurrence was observed and was removed again in November of the same year. Intraoperative findings revealed a tumor that was primarily ochre‐colored, non‐shiny, brittle and suckable. The histopathological diagnosis was folliculosebaceous epithelial proliferative lesion accompanied by an epidermis‐like epithelium and a differentiation into hair follicles and sebaceous gland,s and the tumor was determined to be an epidermoid cyst with proliferative folliculosebaceous epithelium.     

Hyperdense intracranial epidermoid: an uncommon presentation

A thirty year old female presented with sudden onset of severe headache, papilloedema and altered sensorium. Computerised tomography (CT) scan showed a hyperdense vermian mass in the posterior fossa. Operative findings and histological examination revealed spontaneous bleed into the epidermoid cyst. Difficulty in the preoperative diagnosis and uncommon presentation of the intracranial epidermoid cyst prompted us to report this case.     

Primary intracranial squamous cell carcinoma arising in an epidermoid cyst--a case report and review of literature

Primary intracranial squamous cell carcinoma is extremely rare, with most of the cases arising from malignant transformation of an epidermoid or a dermoid cyst. We report here a case of a 45-year-old male patient who presented with 1-month history of intermittent headache and recent onset of altered sensorium. Imaging revealed a midline posterior fossa mass lesion compressing the fourth ventricle and causing hydrocephalus. A provisional diagnosis of dermoid cyst was considered. Histopathological examination revealed a squamous cell carcinoma possibly arising from an underlying epidermoid cyst. This entity is being reported for its rarity.     

Postnatal development and enlargement of primary middle cranial fossa arachnoid cyst recognized on repeat CT scans

The etiology and mechanism of expansion of primary intracranial arachnoid cysts have been much debated. A rare case of an 8-month-old boy is reported, in which postnatal development and enlargement of a middle cranial fossa arachnoid cyst was detected on follow-up CT scans. Based on intraoperative and histological findings, the cyst was found to be intra-arachnoid. The wall was excised completely, and the lobe adjacent to the cyst appeared normal apart from signs of atrophy. Histological study of the excised cyst revealed a common arachnoid membrane with neither ependymal nor inflammatory cells; the cyst fluid was similar to CSF. The etiology of the lesion remains unclear, but it was considered that the expansion of the cyst might have occurred through a ball-valve mechanism of the membrane in communication with the general subarachnoid space.     

Encephalocraniocutaneous lipomatosis: a recently described neurocutaneous syndrome

The authors report a 1-year-old Japanese boy, who was noted to have unilateral alopecia and a cloudy cornea since birth. Additional features included mild spasticity and mental retardation, DQ being 70. A non-communicating cystic lesion was found in the right middle cerebral fossa by metrizamide CT scan, and resection of the lesion by craniotomy revealed an arachnoid cyst. The case was diagnosed as encephalocraniocutaneous lipomatosis, a recently described neurocutaneous syndrome.     

A huge occipital osteoblastoma accompanied with aneurysmal bone cyst in the posterior cranial fossa

Osteoblastoma is an infrequent benign tumor and skull involvement is extremely rare. The occipital bone is much less frequently involved. We report an unusual case of a huge occipital osteoblastoma with aneurysmal bone cyst in the posterior cranial fossa of a 20-year-old young man. MRI scan and CT three-dimensional reconstruction revealed that the tumor (approximately 8.5 cm x 6 cm x 5 cm) occupied nearly half volume of the posterior cranial fossa. The cerebellum, the forth ventricle and brain stem were compressed remarkably and hydrocephalus was noted. The tumor mass was multiloculated cystic and highly vascular. Excessive bleeding occurred during operation and total removal was achieved. The patient was symptom-free and MRI scan revealed no evidence of recrudescence after a follow-up period of 18 months. Pathological examination revealed that the lesion was a benign osteoblastoma with secondary aneurysmal bone cyst (ABC). ABC constitutes a highly vascular lesion while complete surgical resection is often impeded by excessive intraoperative bleeding. Preoperative embolization may reduce the risk. Despite the benign nature of osteoblastoma, local recurrence after incomplete resection is not rare and malignant transformation during recurrence may occur even after adequate surgery. Our case confirms the findings of previous investigators that if osteoblastoma is removed completely, no recurrence is expected even without adjuvant irradiation and chemotherapy.     

Giant intradiploic infratentorial epidermoid cyst

Epidermoid cysts are benign, uncommon lesions (1% of all intracranial tumors). Their localization is intradiploic in 25% of cases, and exceptionally subtentorial. We report here a rare case of giant intradiploic infratentorial epidermoid cyst. A 74-year old patient presented with recent diplopia and sindrome cerebellar. CT scan and MR imaging revealed a giant osteolytic extradural lesion of the posterior fossa (5.2 cm x 3.8 cm) with a small area of peripheral enhancement after contrast injection. Retrosigmoid suboccipital craniectomy allowed a satisfactory removal of the tumor, followed by an acrylic cranioplasty. The outcome was good. Neuropathological examination confirmed an epidermoid cyst. We review the literature and discuss our case.     

Huge arachnoid cyst incorporating choroid plexus

Background We report a rare case of arachnoid cyst incorporating choroid plexus. This 7-month-old girl presented with macrocrania. Magnetic resonance (MR) imaging disclosed a cystic lesion arising from the left prepontine cistern extending to the left middle cranial fossa.Methods First, we performed resection of the membrane microscopically and obtained an adequate reduction of the cystic size. However, 4 months after the first operation, the cyst was enlarged again, and bulging of the portion of the craniotomy was noted. Thus, we performed neuroendoscopic transcortical ventriculo-cyst-cysternostomy and confirmed the choroid plexus inside of the arachnoid cyst.Discussion Postoperative course was uneventful. This is the first reported case of choroid plexus within an arachnoid cyst, determined neuroendoscopically.     

Giant intramedullary epidermoid extending from the brain stem to the upper thoracic spinal cord

Epidermoid cysts are benign tumors originating from ectoderm remnants. Most epidermoid cyst cases are intracranial. Spinal epidermoid cysts are uncommon and most of the reported cases are in the thoracic and lumbar spine. Occurrence of intramedullary epidermoid cysts in the cervical spine is extremely rare. An 18-year-old male with a giant intramedullary tumor extending from the brain stem to the upper thoracic spinal cord presented at our outpatient department. The patient underwent total excision of a silvery white lesion through a midline myelotomy. Histopathological examination was suggestive of an epidermoid cyst. We present a brief report of the case and discuss the relevant literature.     

Intraoperative subdural hematoma in a patient with arachnoid cyst in the middle cranial fossa

A case of arachnoid cyst in the middle cranial fossa complicated by intraoperative subdural hemorrhage is presented. Accumulation of cerebrospinal fluid (CSF) outside the outer wall of the arachnoid cyst was found to induce the rupture of well-developed, fragile leptomeningeal vessels at the base of the middle cranial fossa. This phenomenon is noteworthy as a pitfall in surgery for intracranial arachnoid cyst and suggest the bleeding source of subdural hematoma occasionally associated with this lesion.     

Recurrent intrinsic brain stem epidermoid cyst

The authors report the case of a 14-month-old baby boy with an epidermoid cyst located entirely within the pons and medulla, without an exophytic component. The lesion was examined by computed tomography and magnetic resonance imaging. The child was operated upon three times after two recurrences of the lesion. A suboccipital, subtonsillar approach was used for the first and second procedures and a transtemporal approach for the last one. Excision was thought to be complete the first time, since a solid tumor was found and removed in a large cyst. The cyst wall was not identified. No tumor was found during the second procedure despite recurrence of the cyst, which was drained without an attempt to remove the cyst wall. Finally the cyst recurred with a large tumor in the cyst wall which was again totally removed. Consistent with the high mortality of brain stem epidermoid cysts in the literature, the child eventually died. The therapeutic problems, surgical options, and consequences are discussed.     

Malignant Transformation of an Epidermoid Cyst in the Cerebellopontine Angle

Intracranial squamous cell carcinoma is extremely rare, with most of the cases arising from malignant transformation of an epidermoid or a dermoid cyst. The patient presented with facial weakness. Initial magnetic resonance imaging revealed a mass in the right cerebellopontine angle. A subtotal resection was performed via right retrosigmoid suboccipital approach. Histopathological findings were consistent with an epidermoid tumor. Five months later, the patient underwent gamma knife radiosurgery due to highly probable recurrent epidermoid tumor. Two years after, the patient''s neurological deficit had been newly developed, and follow-up magnetic resonance imaging demonstrated a large contrast-enhancing tumor in the left cerebellopontine angle, which compressed the brainstem. After resection of the tumor, histopathological examinations revealed a squamous cell carcinoma probably arising from an underlying epidermoid cyst. We report a case of an epidermoid tumor in the cerebellopontine angle that transformed into a squamous cell carcinoma.     

经眶入路神经内镜手术治疗颅中窝底病变的疗效分析（附17例报道）

目的 探讨神经内镜下经眶入路（ETOA）手术治疗颅中窝底肿瘤的疗效。方法回顾性分析2017年6月至2021年3月ETOA手术治疗的17例颅中窝底病变的临床资料。结果术后病理显示脑膜瘤9例，胶质瘤3例，神经鞘瘤2例，淋巴瘤1例，海绵状血管瘤1例，血管外皮细胞瘤1例。肿瘤全切除11例，次全切除5例，部分切除1例。术后出现脑脊液漏2例、短暂性动眼神经麻痹3例、脑梗死1例、颅内大出血1例（再次手术）。出院后随访6~24个月，无死亡病例；1例次全切除胶质瘤术后12个月出现进展，二次手术；其余病例未见复发或进展。术后6个月，改良Rankin量表评分0~2分14例，3分3例。结论ETOA手术是治疗颅中窝底病变的有效方法，可达到令人满意的切除程度，并有效地减少并发症。     

Cholesterol granuloma of the cerebello-pontine angle.

An unusual case of cholesterol granuloma of the temporal bone is described presenting as a cerebellopontine tumor. This lesion seemed to arise from an inflammatory process obstructing pneumatized cells. It consists of extradural granulation tissue and must be distinguished from intradural epidermoid cyst, which is, instead, a dysembryogenetic neoplasm. Simple drainage of the granuloma was accomplished by posterior fossa approach, but the lesion recurred after a year. The diagnosis and surgical management of cholesterol granuloma are discussed.     

The presence of intraventricular fat in a case of dermoid cyst

A 21-year-old man presented an 11-year history of generalized and temporal lobe epilepsy. In 1993 he was diagnosed by the MRI scan to have intracranial expansive lesion and underwent a subtotal removal of an epidermoid cyst. Two years later a follow-up MRI scan showed the presence of fat in the anterior horns of the lateral ventricles. In 1998 he was reinvestigated because of the increased frequency of epileptic seizures and resistance to pharmacological treatment. MRI scan showed enlargement of the cyst and presence of the same amount of intraventricular fat as in the previous examination. The radical removal of the tumor was carried out and histological examination revealed that in fact we were dealing with a dermoid cyst. During a four-year postoperative follow-up, there was no evidence of recurrence of the tumor and the amount of intraventricular fat remained unchanged. The presence of fat in CSF spaces is an indication of possible presence of specific intracranial pathology, which requires clarification. The quantity of fat may remain unchanged for many years or indefinitely.     

Endodermal cyst in the cerebellopontine angle with immunohistochemical reactivity for CA19-9

We present a rare case of the endodermal cyst in the cerebellopontine angle with positive immunohistochemical reactivity for CA19-9. The patient was a 67-year-old woman with an endodermal cyst in the cerebellopontine angle who presented with progressive gait disturbance. A magnetic resonance image showed a cerebellopontine angle which was low in signal on T1-weighted, and high on T2-weighted image without gadolinium enhancement. The preoperative diagnosis was an epidermoid or arachnoid cyst. The patient underwent surgery. Since the intraoperative histological diagnosis by frozen section was endodermal cyst, total removal of the cyst wall was achieved for preventing recurrence. The postoperative definitive histological diagnosis was endodermal cyst, type A by Wilkins-Odom classification, lined by mucinous epithelium with an immunohistochemical reactivity for CA 19-9 protein and cytokeratin. This is the first reported case of a huge endodermal cyst in the cerebellopontine angle of an elderly woman which exclusively showed a differentiation toward the midgut epithelium. The histological diagnosis during surgery by frozen section should be performed for proper treatment.