Epidermoid cysts of the skull base are rare. We present the case of a woman with an epidermoid cyst at the root of the sphenoidal pterygoid process. She experienced tightness of the forehead skin without headache. Computed tomography (CT) scan revealed a hypodense lesion at the base of the skull in the right middle cranial fossa, which had partly eroded the pterygoid root. Magnetic resonance imaging (MRI) scan revealed a soft cystic mass that eroded the pterygoid root with hypo-/iso-intense on T1-weighted images, hyperintense on T2-weighted images, inhomogeneous hyperintense on diffusion-weighted images, a slightly low apparent diffusion coefficient, and no enhancement, suggesting a diagnosis of an epidermoid cyst. Surgical excision was performed using a nasal endoscope via the pterygoid process-root approach. A histopathological examination confirmed the diagnosis of an epidermoid cyst. At the 6-month follow-up, no recurrence was found on MRI or nasal endoscopy, and the symptoms of forehead tightness disappeared. In conclusion, epidermoid cysts at the root of the sphenoidal pterygoid process are exceptionally rare. Preoperative MRI and CT scans are necessary for the correct diagnosis and differentiation of other low-growing lesions. Nasal endoscopy is crucial for surgical excision and postoperative follow-up for potential recurrence.

OBJECTIVE: This study aims to examine the clinical characteristics and surgical management of pediatric testicular epidermoid cysts, thereby contributing to the existing body of knowledge pertinent to the diagnosis and therapeutic intervention s for this condition.
METHODS: A retrospective analysis was conducted on the clinical records of 23 pediatric patients diagnosed with testicular epidermoid cysts, who were admitted to our institution between April 2013 and February 2024. Concurrently, a comprehensive review and analysis of pertinent literature were undertaken to augment the findings.
RESULTS: The mean age at which the onset of epidermoid cysts was observed was 6.0 years. All cases were singular and unilateral. B-ultrasound diagnosis categorized 6 cases as epidermoid cysts, 11 as teratomas, and 6 as indeterminate, yielding a diagnostic sensitivity of 26.1%. All patients underwent testicle-sparing mass resection, and nine patients underwent rapid intraoperative frozen section analysis, revealing eight cases of testicular epidermoid cysts and one teratoma, with a diagnostic sensitivity of 88.89%. Postoperative histopathological examination confirmed the diagnosis of testicular epidermoid cyst.
CONCLUSIONS: Pediatric testicular epidermoid cysts are an uncommon occurrence, primarily presenting as a painless scrotal mass, which can mimic the clinical features of malignant testicular tumors. Imaging modalities and histopathological assessment are pivotal in the diagnostic process for pediatric testicular epidermoid cysts. For cases where B-ultrasound is inconclusive, rapid intraoperative pathological examination should be considered.

BACKGROUND: A peri-implant cystic lesion is a rare finding, and to date most investigators have considered that its pathogenesis is caused by trauma and infection related to dental implantation. However, the pathogenesis of these cysts remains unclear and is recognized to have multifactorial origins.
METHODS: In February 2021, a 75-year-old male patient underwent implant restoration due to mobility of the left maxillary central incisor. The implant achieved good osseointegration and was successfully restored. However, in March 2023, the patient sought treatment due to mobility of the dental implant. Clinical examination showed that the implant had loosened in three directions (vertical, mesial-distal, and labial-lingual), and the peri-implant mucosa was slightly red and swollen. Radiographic examination (cone beam computed tomography) showed a large radiolucent area with clear boundaries involving the cervical and middle portions of the dental implant, and white bone lines were observed at the edge of the low-density shadow. Intraoperatively, we removed the patient\'s implant, performed a complete debridement, and conducted bone augmentation surgery in the area of bone defect. Postoperatively, the patient recovered well. The final histopathological result confirmed an epidermoid cyst.
CONCLUSIONS: Peri-implant epidermoid cyst is a rare complication that affects the long-term outcome of implant therapy. This case serves as a warning to clinicians to avoid involving epithelial tissue in the implant site during implant surgery, in order to prevent the potential occurrence of a peri-implant epidermoid cyst, thereby creating better conditions for the patient\'s recovery and the long-term efficacy of the implant.

BACKGROUND: Pilomatricoma has various manifestations on color Doppler ultrasound, and a differential diagnosis is challenging. The objective of this study was to investigate which characteristics of skin lesions on color Doppler ultrasound are effective in distinguishing pilomatricoma from epidermoid cyst and dermatofibrosarcoma protuberans.
METHODS: Records of patients with pilomatricomas (n = 63), epidermoid cysts (n = 76), and dermatofibrosarcoma protuberans (n = 19) who underwent color Doppler ultrasound evaluation and surgical excision were reviewed. The anatomical distribution and color Doppler ultrasound characteristics of these lesions were analyzed. The 63 pilomatricomas were categorized into five types based on their color Doppler ultrasound characteristics, and the roles of these five types in the differential diagnosis of the aforementioned diseases were studied.
RESULTS: Pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans exhibited some similar characteristics. Dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity were the major characteristics of pilomatricomas. The pilomatricomas could be categorized into five types, with type II having a diagnostic performance of sensitivity of 65.08%, specificity of 98.95%, area under the receiver operating characteristic curve (AUC) of 0.743, positive predictive value of 97.62%, and negative predictive value of 81.03% for the diagnosis of the aforementioned skin diseases.
CONCLUSIONS: A combination of dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity exhibits higher diagnostic performance for the differential diagnosis of pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans.

The objective of this study is to preliminarily investigate the surgical safety, efficacy, techniques, and clinical value of fully neuroendoscopic surgery for the resection of cerebellopontine angle (CPA) tumors via a retrosigmoid approach. The clinical data of 47 cerebellopontine angle area (CPA) tumors that were treated by full neuroendoscopic surgery from June 2014 to June 2023 were retrospectively analyzed. The efficacy and advantages of the surgical techniques were evaluated based on indicators such as duration of the surgery, neuroendoscopic techniques, intraoperative integrity of nerves and blood vessels, extent of tumor resection, outcomes or postoperative symptoms, and incidence of complications. The 47 cases of cerebellopontine angle tumors include 34 cases of epidermoid cysts, 7 cases of vestibular schwannomas, and 6 cases of meningiomas. All patients underwent fully neuroendoscopic surgery. Twenty tumors were removed using the one-surgeon two-hands technique, and 27 tumors were removed using the two-surgeons four-hands technique. The anatomical integrity of the affected cranial nerves was preserved in all 47 cases. None of the patients suffered a postoperative hemorrhage, cerebrospinal fluid leak, and aseptic or septic meningitis, or died. The rate of total tumor resection was 72.3% (34/47), and the symptom improvement rate was 89.4% (42/47). All patients were followed up for 2 to 12 months, and none died nor showed any signs of tumor recurrence. By analyzing 47 fully neuroendoscopic resections of CPA tumors using the posterior sigmoid sinus approach in our center, we believe that such method allows complete, safe, and effective resection of CPA tumors and is thereby worthy of clinical promotion.

Epidermoid cysts originate from ectopic embryonic epithelial cells and are a very common type of benign intracranial tumor. However, the incidence of intraventricular epidermoid cysts is low, and lateral intraventricular epidermoid cysts are even rarer. Here, we present a case of lateral intraventricular epidermoid cyst and review the relevant literature. A 54-year-old female complained of recurrent headaches over a 5-year period, with aggravated symptoms during the last 2 months or more. A computed tomography of the brain showed a low-density mass in the lateral ventricle and enlargement of the right ventricle. Cranial magnetic resonance imaging further confirmed that the mass was an epidermoid cyst. The patient underwent microscopic surgical resection combined with endoscopy using an interhemispheric craniotomy approach. The mass was satisfactorily removed, and the patient recovered well. Lateral intraventricular epidermoid cysts often present with clinical symptoms due to the invasion of surrounding brain tissue or blockage of the cerebrospinal fluid system. Diagnosis relies on examination by magnetic resonance imaging, and treatment relies on surgical resection. The prognoses of patients are mostly excellent and depend on whether the tumor is resected cleanly or not.

Epidermoid cysts are generally benign neoplastic lesions, the etiology of which is unclear and is mainly related to epithelial cells left in the tissues during the embryonic period and traumatically implanted in the tissues. The most common intraosseous sites are the phalanges and the skull. Epidermoid cysts occurring in the jaws are clinically rare. In this paper, we report a case of epidermoid cyst occurring in the mandible with embedded teeth and discuss the etiology, clinical manifestations, diagnosis, and treatment of epidermoid cysts in the jaws in the context of the relevant literature.

Secondary spinal arachnoid cysts have rarely been reported but present significant challenges for management. These cysts could be anteriorly located with long rostral-caudal extensions and many are related to arachnoiditis, leading to difficult-to-treat disorders. Thus far, due to the scarcity of reports, the features of the disease and the optimal therapeutic strategies remain unclear.
To investigate clinical features and the optimal treatment modalities of secondary spinal arachnoid cysts compared with primary spinal arachnoid cysts.
Systematic review.
Systematic review identified 103 secondary cases from 80 studies and reports.
Condition of symptom relief and duration of treatment response were analyzed.
An electronic literature search of the PubMed database was conducted for studies on secondary spinal arachnoid cysts between 1990 and 2022. Non-English publications, nonhuman studies, reports of a primary cyst, studies not including case details, and studies of nonsymptomatic cases were excluded.
This systematic review included 103 secondary cases. The most commonly reported etiologies were iatrogenic factors, trauma, and subarachnoid hemorrhage, accounting for 88 intradural extramedullary, 11 extradural, one intradural/extradural, one interdural, and one intramedullary spinal arachnoid cyst after a median duration of 30, 12, and 9 months, respectively. Extradural cysts were more prone to occur at dorsal locations and affect thoracic segments (mean cyst length: 3.4 segments). Intradural cysts showed a relatively higher ventral/dorsal ratio (1:1.09, 1.75:1, and 3.50:1 for cysts occurring from iatrogenic factors, trauma, and subarachnoid hemorrhage, respectively) and thoracic distribution, with a mean cyst length of 4.3 segments (5.1 for ventral and 3.5 for dorsal cysts). For intradural cysts, recurrence risk was lower after surgical resection than after fenestration/marsupialization (12-month recurrence risk: 21.43% vs 50.72%, log-rank test: p=.0248, Gehan-Breslow-Wilcoxon test: p=.0126). In cases treated with shunting, one recurrence (1/8 cases) was noted after external shunting and two recurrences (2/5 cases) after internal shunting at a median follow up of 12 months.
Secondary spinal arachnoid cysts, particularly intradural cysts, are rarer and more challenging to treat than primary spinal cysts. Although fenestration/marsupialization is the commonly adopted treatment, the recurrence rate is high. For unresectable cysts, shunting procedures, particularly shunting into a body cavity (eg, pleural or peritoneal cavity) away from the subarachnoid space, could be a therapeutic alternative besides fenestration/marupialization, yet its efficacy requires confirmation by more data.

OBJECTIVE: This study was aimed to evaluate the diagnostic performance of ultrasound (US) in differentiating trichilemmal cysts (TCs) from epidermoid cysts (ECs).
METHODS: Based on clinical and ultrasound features, a prediction model was established and validated. 164 cysts in the pilot cohort and another 69 in the validation cohort diagnosed with TCs or ECs histopathologically were evaluated. The same radiologist performed all ultrasound examinations.
RESULTS: For clinic features, TCs tended to occur in females compared with ECs (66.7 vs 28.5%; P < .001). In addition, TCs were prone to occur in the hairy area compared with ECs (77.8 vs 13.1%; P < .001). For ultrasound features, the internal hyperechogenicity and cystic change were more likely to appear in TCs in comparison with ECs (92.6 vs 25.5%; P < .001; 70.4 vs 23.4%; P < .001, respectively). Upon the features mentioned above, a prediction model was established with the areas under the receiver operating characteristic curves of 0.936 and 0.864 in the pilot and validation cohorts, respectively.
CONCLUSIONS: US is promising for differentiating TCs from ECs and is valuable for their clinical management.

UNASSIGNED: Epidermoid cysts of cavernous sinus (CS) are rare congenital neoplasms of the central nervous system. In previous literature reports, the treatment for CS epidermoid cysts was mainly microsurgical resection, and the surgical methods included simple microsurgery and endoscope-assisted microsurgery. The present case report demonstrates the first case of complete resection of a CS epidermoid cyst by a simple endoscopic endonasal transcavernous (EET) approach.
UNASSIGNED: A 54-year-old woman presented with chronic persistent headaches and occasional syncope. Brain MRI demonstrated a space-occupying lesion of the left CS, and digital substruction angiography (DSA) showed a small aneurysm at the beginning of the left ophthalmic artery. Thrombotic therapy of carotid-ophthalmic aneurysms was performed first, and the patient underwent resection of the CS lesion secondary. Considering the location of the lesion and the neuroendoscopy technology and experience of the doctor, we made bold innovations and used an EET approach to achieve complete resection of the lesion. The postoperative pathological results were consistent with the characteristics of epidermoid cyst. During the 1-year follow up, the patient showed no apparent signs of recurrence on head MRI.
UNASSIGNED: Epidermoid cyst of cavernous sinus is a rare benign occupying lesion in cavernous sinus. Reviewing the previous literature, the main treatment is microneurosurgery, and neuroendoscopy is only used as an auxiliary equipment. We present the first case of complete endoscopic resection of CS epidermoid cyst by EET approach according to CARE guidelines, aiming to share the new surgical plan for CS epidermoid cyst and provide more surgical options for this disease for neurosurgery colleagues.