Integrating vascularity into the pattern classification of pilomatricomas on ultrasound provides a more competent approach for discriminative evaluation.

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. MATERIALS AND 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. CONCLUSION: 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.

Effect of Epidermoid Cysts on the Efficacy of Intralesional Corticosteroid Therapy for Hypertrophic Scars and Keloids: A Prospective Pilot Study.

BACKGROUND: Patients with hypertrophic scars (HSs) or keloids occasionally have epidermoid cysts (ECs), and the effect of ECs on the effectiveness of intralesional corticosteroids (ILCs) treatment in these patients has not been reported. OBJECTIVE: This study aims to evaluate the influence of ECs on the outcomes of ILCs treatment in patients with HSs or keloids. MATERIALS AND METHODS: This prospective study included 572 patients with keloids ( n = 461) or HSs ( n = 111). Patients received intralesional triamcinolone acetonide injection (0.05 mL/injection) at a concentration of 40 mg/mL and every 28 days for 4 sessions, with a 1-year follow-up. RESULTS: A higher incidence of ECs was observed in keloid patients (16.92%) compared with HSs patients (7.21%). Keloid patients with ECs were older ( p = .008) and had a longer disease duration ( p = .0148), higher Vancouver scar scale (VSS) scores ( p = .04), and greater thickness ( p = .006). Keloid patients with ECs showed less improvement in VSS scores ( p < .0001) and thickness ( p < .0001) after ILCs treatment, with a higher recurrence rate ( p < .0001). The overall complication rate in keloid patients with ECs after ILCs treatment was 49.51%. CONCLUSION: Epidermoid cysts under keloids were associated with a poor response to ILCs therapy. Therefore, it is recommended to incorporate ultrasonography as a routine examination for keloid patients to aid in better decision making in clinical practice.

Spontaneous regression of an epidermoid cyst in a pediatric patient-Case report and review of the literature.

Epidermoid cysts are infrequent, benign, slow-growing, space-occupying lesions that account for 0.5-1.8% of primary intracranial tumors. We report the case of a 17-month-old child who presented in 2015 for one episode of pallor associated with hypotonia. Epilepsy was excluded and MRI was recommended. The MRI was performed and there were no focal parenchymal lesions, but it showed an extra-axial ovoid lesion with imaging characteristics consistent with epidermoid cyst. Follow-up MRI at one year was performed and it showed minimal increased in dimensions of the cyst, without changes into the signal of the lesion. Another MRI was performed 7 years after and it showed complete resolution of the cyst. Six months afterwards, another MRI was performed and it confirmed the complete regression of the cyst, without any extra-axial masses reported. The patient did not present any neurological anomalies. No follow-up MRI was recommended afterwards. Spontaneous regression of epidermoid cyst in pediatric population is an extremely rare event, but it should be taken into account when the patient shows no symptoms. This is the third case of spontaneous regression of an epidermoid cyst reported in pediatric patients, and the first one in the temporal region. Careful follow-up and watchful waiting could be an option to surgical treatment in epidermoid cysts.

Adelola Adeyole (1935-2021): Early descriptor of congenital dermoid or epidermoid inclusion cyst over the anterior fontanelle and below the galea aponeurotica.

The author wished to detail the life and contributions of Dr. Adelola Adeloye, MBBS, MS, FWCS, FRCS, FACS, FRCP, in hope to pay homage to this giant in Global Neurosurgery. Dr. Adelola Adeloye was born on July 18, 1935 in Illesa, Osun State, present-day South-West Nigeria. The Adeloye-Odeku disease is an eponym for a congenital dermoid or epidermoid inclusion cyst (CDIC/CEDIC) over the anterior fontanelle and below the galea aponeurotica. In 1971, Adeloye and Odeku first described these cysts in 18 Nigerian patients. While overall rare and predominantly noted in children, the Adeloye-Odeku disease has been found to impact adults too. In terms of rarity, CDICs make up 0.1-0.5% of cranial tumors and 0.2% of inclusion cysts. CDICs can be distinguished from CEDICs through histopathology as dermoid cysts may contain hair follicles, sweat, sebaceous glands, and teeth, whereas CEDICs usually are only composed of keratinized debris and epidermal tissue. Assumed first to be an African cyst, cases of the Adeloye-Odeku disease were subsequently reported in other ethnic populations: Turkish, Czechs, Slovaks, Chinese, Japanese, Canadians, Saudi Arabians, Indians, Caucasians, Bangladeshis, Spaniards, and Brazilians.

Sonographic Findings of Cervical Chondrocutaneous Branchial Remnants-A Comparison With Dermal Lesions/Cysts and a Literature Review: A Pilot Study.

OBJECTIVES: Cervical chondrocutaneous branchial remnants (CCBRs) and dermal lesions, such as epidermoid cysts or brachial anomalies, including lateral cervical cysts/sinuses or dermal sinuses of anterior chest lesions, are usually located at the lower neck at the anterior or posterior border of the sternocleidomastoid muscle (SCM). We aimed to demonstrate the usefulness of ultrasonography in the differential diagnosis and evaluation of CCBRs. METHODS: We evaluated 22 lesions of 20 pediatric patients, classified into CCBR and dermal lesion groups. We used Fisher's exact test to evaluate differences between these groups in terms of lesion shape (low-echoic mass- or tubular-like), whether the lesion was adjacent to/in contact with the SCM or not, and the presence or absence of a concave SCM caused by the lesion. RESULTS: Of the 22 lesions, 8 were CCBRs, and 14 were dermal lesions. We found a significant difference in the presence/absence of adjacency to or contact with the SCM (presence/absence of adjacency to or contact with the SCM in CCBRs vs that in dermal lesions: 6/2 vs 1/13, P = .002) and presence/absence of lesion-induced concavity of the SCM (presence/absence of lesion-induced concavity of the SCM in CCBRs vs that in dermal lesions: 3/5 vs 0/14, P = .036). The lesion shape (low-echoic mass-like/tubular-like lesions) did not significantly differ between the two study groups (low-echoic mass-like/tubular-like lesions in CCBRs vs that in dermal lesions: 5/3 vs 11/6, P = .624). CONCLUSIONS: CCBRs have a strong association with the SCM. These sonographic findings may be useful in the differential diagnosis of dermal cervical lesions.

Perineal Squamous Cell Carcinoma Arising in an Epidermal Cyst.

A 90-year-old Japanese woman who had been aware of a subcutaneous mass on the right perineal region for 5 years was referred to our hospital for further examination and treatment because of the rapid growth of the mass and bleeding that began 3 months earlier. A biopsy of the mass revealed a diagnosis of well-differentiated squamous cell carcinoma. On preoperative examination, the tumor was 90×40 mm in size and was suspected to have partially invaded the levator ani muscle and external sphincter. Since a preoperative cardiac evaluation indicated severe aortic stenosis, we performed transcatheter aortic valve implantation. A radical resection was then performed with general anesthesia. The skin and subcutaneous tissue defects were reconstructed with a posterior gluteal-thigh propeller flap, and a sigmoid colostomy was created. The patient had a good postoperative course and was transferred to a rehabilitation facility 28 days after the surgery. Epidermal cysts are a common benign tumor, and clinicians should keep in mind that these cysts can become malignant.

Squamous Cell Carcinoma Arising From Epidermal Cyst: A Case Series of 9 Patients With a Literature Review.

ABSTRACT: Epidermal cysts are among the most common benign subcutaneous tumors. However, malignant transformation of benign epidermal cysts into squamous carcinomas has been reported. Owing to its low incidence rate, the clinical and pathological features of this condition are not well understood. This study aimed to analyze the clinical and pathological characteristics of the malignant transformation of epidermal cysts, which could suggest an appropriate treatment strategy. We conducted a retrospective study of 9 patients diagnosed with squamous cell carcinoma arising from epidermal cysts. All patients underwent surgical excision, and clinical information regarding patient demographics, tumor characteristics, treatment, and outcomes was analyzed. The average age at diagnosis was 57.3 years, with an average latency period of 15.4 years. Five patients had undergone prior cyst excision or drainage, with an average of 2.3 episodes of recurrence. Surgical excision was the primary treatment in all cases, and 2 patients with margin involvement at the final pathology underwent re-excision with additional resection margins. No recurrence was observed during the follow-up period. Four patients had immune dysregulation due to an underlying chronic kidney disease or cancer. Our study emphasizes the need for increased awareness of squamous cell carcinoma arising from epidermal cysts in patients with a history of cyst existence or recurrence, especially those with immune deficiencies. We expect these findings to contribute to early suspicion of malignant transformation and guide adequate clinical decision-making.

Invasive Squamous Cell Carcinoma Arising From a Cystic Brow Mass.

An 82-year-old woman presented with a 6-month history of an enlarging brow mass that developed after trauma. Clinical and MRI appearance of the lesion appeared consistent with epidermal inclusion cyst. However, excisional biopsy demonstrated invasive squamous cell carcinoma, which recurred 6 weeks later and required repeat surgical excision. To our knowledge, this represents the first case of squamous cell carcinoma arising from a posttraumatic epidermal inclusion cyst.

Correlation Between Radiologic and Histopathologic Features of Orbital Epidermoid and Dermoid Cysts.

PURPOSE: Epidermoid cysts (EC) and dermoid cysts (DC) typically appear as well-circumscribed lesions on CT. This study aimed to clarify the radiologic and histopathologic characteristics of orbital EC and DC and to determine the correlations between them. METHODS: The medical records of 69 patients who underwent surgery for orbital DC or EC at Samsung Medical Center between January 2001 and August 2016 were retrospectively reviewed. The size and location of the cysts, rim enhancement, homogeneity of contents, presence of hemorrhagic or calcific components, radiodensity of contents, and extent of bony remodeling were evaluated using CT. Additionally, the cyst lining and contents were examined histopathologically. RESULTS: Among patients with orbital cysts, EC and DC were diagnosed in 10 (14.5%) and 59 (85.5%) patients, respectively. Further, 50.0% of EC and 79.7% of DC were located in the superotemporal quadrant of the orbit. On orbital CT, the average radiodensity of EC and DC was 18.9 ± 56.2 and -67.9 ± 63.3 HU, respectively. The cystic contents were more frequently homogeneous than heterogeneous in both EC and DC; however, the radiodensity of cysts differed significantly, which may be attributed to sebaceous gland activity. Focal bony notching, bone remodeling under pressure, and bony changes from dumbbell-shaped cysts were observed more frequently in DC than in EC. CONCLUSIONS: Radiological and histopathological features are correlated in orbital EC and DC. Therefore, orbital EC and DC can be preoperatively differentiated using CT, based on the average radiodensity and bony remodeling.

Clinical analysis of 23 cases of epidermoid cyst of testis in children.

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.

Applying the Full Endoscopic Keyhole Technique to CPA Lesions: A Single-Center Study.

In recent years, endoscopy has become an increasingly common tool used during neurosurgical procedures. However, its application in treating cerebellopontine angle (CPA) lesions has not progressed as rapidly. In this study, the authors present their initial experience with surgically treating CPA lesions using a fully endoscopic keyhole retrosigmoid approach. They conducted a retrospective analysis of clinical data from patients who underwent endoscopic keyhole CPA surgery at their center between May 2017 and April 2022. They provide a comprehensive explanation of this method and an overview of the strategies that have been developed to achieve better clinical outcomes. The study included 107 patients, consisting of 10 cases of vestibular schwannoma, 21 cases of epidermoid cyst, 32 cases of trigeminal neuralgia, and 44 cases of hemifacial spasm. The authors analyzed the clinicodemographic details of the patients. Among the 31 tumor cases, gross total resection was achieved in 25 patients (80.6%), while near-total resection was performed in 6 patients (19.4%). In patients with trigeminal neuralgia, facial pain resolved in 31 out of 32 patients (96.9%). Similarly, facial convulsions disappeared or were relieved in all 44 patients (100%) with hemifacial spasms after the operation. Postoperative complications included facial nerve paresis (n=9, 8.4%), with improvement observed in 6 cases during follow-up, transient facial hypoesthesia (n=3, 2.8%), cerebrospinal fluid rhinorrhea (n=3, 2.8%), transient abducens paresis (n=1, 0.9%), and postoperative hemorrhage (n=1, 0.9%). Endoscopy provides improved deep illumination and, combined with close-up observation, enhances the visualization of structures within the CPA region. The fully endoscopic keyhole technique is a safe and effective method for managing CPA lesions.

Diagnosis of an epidermoid retroperitoneal cyst via ultrasound: A case report.

Retroperitoneal cysts (RPCs) are rare types of cyst in the retroperitoneal space that are frequently misdiagnosed as gynecological tumors. This case report details, an epidermoid RPC, identified through 2D ultrasound, with attempts to visualize its rendered images using 3D ultrasound. A 39-year-old female patient was admitted to the hospital following the detection of a pelvic mass during a routine physical examination. Initially, the lesion was suspected to be an ovarian tumor, but subsequent ultrasound investigations suggested an epidermoid RPC. This diagnosis was later confirmed by pelvic magnetic resonance imaging. The definitive diagnosis was made following laparoscopic exploration and pathological examination. This case is shared to analyze the ultrasound characteristics of epidermoid RPCs.

Comedones and epidermal cysts on the abdominal skin of a dog occurring after a laparotomy.

An 8-year-old neutered male shih tzu dog underwent laparotomy for cystolithectomy. Ten days later, multiple various-sized cystic nodules were observed on the suture line and surrounding abdominal skin, although the surgical incision had healed well. Microscopically, various-sized cysts lined with thin walls of stratified squamous epithelium in the dermis were dilated and filled with keratin. Adnexal differentiation from the wall was not seen. Thus, the abdominal lesions were diagnosed as comedones and epidermal cysts. Herein, we describe the case of a dog with comedones and epidermal cysts on the abdominal skin after a laparotomy. Key clinical message: Multiple various-sized cystic lesions of the follicles are described. The implantation of epidermal fragments into the dermis by surgery may induce epidermal cysts and comedones in the skin of hyperadrenocorticism-affected dogs.

Comédons et kystes épidermiques sur la peau abdominale d'un chien survenant après une laparotomie. Un chien shih tzu mâle castré de 8 ans a subi une laparotomie pour cystolithectomie. Dix jours plus tard, de multiples nodules kystiques de différentes tailles ont été observés sur la ligne de suture et sur la peau abdominale environnante, bien que l'incision chirurgicale ait bien cicatrisé. Au microscope, des kystes de différentes tailles bordés de fines parois d'épithélium pavimenteux stratifié dans le derme étaient dilatés et remplis de kératine. Aucune différenciation annexielle par rapport à la paroi n'a été observée. Ainsi, les lésions abdominales ont été diagnostiquées comme des comédons et des kystes épidermiques. Nous décrivons ici le cas d'un chien présentant des comédons et des kystes épidermiques sur la peau abdominale après une laparotomie.Message clinique clé:De multiples lésions kystiques des follicules, de différentes tailles, sont décrites. L'implantation chirurgicale de fragments d'épiderme dans le derme peut provoquer des kystes épidermiques et des comédons dans la peau des chiens atteints d'hypercorticisme.(Traduit par Dr Serge Messier).

Modified Orbitozygomatic Craniotomy Approach for a Recurrent Orbital Tumor in a Pediatric Patient.

Background: This report aims to present the case of a pediatric patient with a recurrent tumor in the superolateral orbit. Clinical Presentation: An 8-year-old patient was initially treated for a tumor in the superolateral orbit via a transconjunctival approach. The histopathological diagnosis was epidermoid cyst. Postoperatively, chronic inflammation and fistula developed in the lateral canthus area. Magnetic resonance imaging revealed a residual tumor posterior to the original tumor location. The patient was treated via a modified orbitozygomatic (mOZ) craniotomy approach that was originally applied in neurosurgery, and complete tumor removal was achieved. A temporary paralysis of the frontotemporal branch of the facial nerve was observed and fully resolved within one month following surgery. At the 18th month of follow-up, the visual, neurological, and cosmetic results were found to be satisfactory. Conclusions: mOZ craniotomy can be used to access and operate on recurrent orbital tumors in pediatric patients where other more aggressive surgical approaches should be avoided.

[A Case of Lymphoepithelial Cyst of the Pancreas for Which Malignancy Could Not Be Ruled Out Difficult Preoperative Diagnosis].

Lymphoepithelial cyst(LEC)of the pancreas is a relatively rare benign cystic disease of the pancreas. In this report, we describe a case of LEC in which a malignant tumor could not be ruled out by preoperative diagnosis and surgery was performed. The patient was a 72-year-old man. A simple CT scan of the chest and abdomen performed as a follow-up for another disease incidentally revealed a mass in the pancreatic tail. Enhanced CT of the abdomen showed a tumor approximately 3 cm in size at the pancreatic tail with no contrast effect. MRCP showed moderate signal on T2WI, high signal on T1WI, and high signal on T2WI on some cysts inside the pancreas. PET-CT showed slight uptake of FDG. Both tumor markers CEA and CA19-9 were normal. Therefore, malignant disease such as pancreatic IPMC could not be ruled out, and laparoscopic distal pancreatectomy plus splenectomy was performed. The pathology results showed a diagnosis of pancreatic lymphoepithelial cyst with slight differentiation into sebaceous gland.

A comparative study of pilomatricoma and epidermoid cyst with ultrasound.

AIM: To explore and compare the ultrasonic (US) features of pilomatricoma (PM) and epidermoid cyst (EC) in the differential diagnosis and improve the accuracy of US diagnosis of PM. MATERIALS AND METHODS: Three hundred and nine patients who underwent US examination before surgery with a histopathological diagnosis of PM or EC after surgery were analysed retrospectively. The patients were categorised into the training and validation sets according to the inspection times. Univariate analysis was undertaken on the US and clinical features of PM and statistically significant variables (p<0.05) were included in the multivariate logistic regression model to establish a diagnostic model. RESULTS: The results demonstrated that the multivariate logistic regression model for PM was statistically significant (p<0.001). The risk factors included posterior echo attenuation and hypoechoic halos (odds ratio [OR] = 9.277, 10.254) and the protective factors included age, diameter thickness, and posterior echo enhancement (OR=0.936, 0.302, 0.156). The performance of the diagnostic model was tested using the training set (area under the receiver operating characteristic curve [AUC] = 0.974, 95% confidence interval [CI] = 0.955-0.994) and the validation set (AUC = 0.967, 95% CI = 0.926-1.000), which demonstrated good discriminant ability. CONCLUSIONS: The diagnostic accuracy for PM was higher than that for EC when the nodule is characterised by posterior echo attenuation, hypoechoic halos, smaller thickness, and younger age. The US diagnostic model developed may be used to guide the diagnosis of PM.

Diagnostic value of high-frequency ultrasound (HFUS) in evaluation of subcutaneous lesions.

BACKGROUND: It is unknown whether high-frequency ultrasound (HFUS) can evaluate invisible subcutaneous lesions. We aimed to investigate the diagnostic value of HFUS in invisible subcutaneous lesions. METHOD: Patients with invisible subcutaneous lesions were prospectively recruited from two centres. Before undergoing biopsy or surgery, each lesion was independently evaluated by two clinicians. One provides a clinical diagnosis by only clinical examination and the other provides an integrated diagnosis by combining clinical examination and HFUS information. Diagnoses were classified as correct, wrong, and indeterminate. A total of 391 lesions from 355 patients were enrolled, including 225 epidermoid cysts, 77 lipomas, 25 pilomatrixomas, 21 haemangiomas, 19 dermatofibromas, 11 dermatofibrosarcoma protuberans (DFSP), 7 neurofibromas, and 6 leiomyomas. Using pathological results as the gold standard, diagnostic performance was compared. RESULTS: The number of correct diagnoses increased from 185 (47.3%) by clinical examination alone to 316 (80.8%) after the addition of HFUS (P < 0.05). Meanwhile, the indeterminate diagnosis rate decreased from 143 (36.6%) to 10 (2.6%). Using HFUS, the accuracy improved significantly for epidermoid cysts (59.6% vs. 86.7%), lipomas (50.6% vs. 94.8%), pilomatrixomas (0% vs. 48.0%), haemangiomas (23.8% vs. 57.1%), and DFSPs (0% vs. 81.8%) (all p < 0.05). However, HFUS did not significantly improve the diagnostic accuracy of dermatofibromas (15.8% vs. 21.1%, p > 0.999), neurofibromas (42.9% vs. 71.4%, p = 0.625), or leiomyomas (16.7% vs. 100%, p = 0.063). CONCLUSION: Combining HFUS and clinical examination can generally improve the diagnostic accuracy and decrease the indeterminacy of invisible subcutaneous lesions, especially epidermoid cysts, lipomas, pilomatrixomas, haemangiomas, and DFSPs. However, for some rare lesions, HFUS cannot provide useful information.

Proliferating Pilar Tumors in the Scalp Over a Period of 23 Years in a General Hospital in Mexico City.

BACKGROUND: Proliferating pilar tumors are an unusual skin tumor, and they have a cystic component with trichilemmal keratinization and epithelial proliferation. These arise from the outer root sheath of hair follicles. It mainly affects women. The scalp is the most affected area. Diagnosis can be made by biopsy. Surgical excision is the best treatment option. OBJECTIVE: Report the frequency of proliferating pilar tumors in the scalp in general hospital in Mexico over a period of 23 years. METHODS: The authors reviewed the database of the dermatopathology service of the General Hospital "Dr Manuel Gea González" from 1999 to August 2022, selecting diagnosticated cases of proliferating pilar tumor, pilar cyst, trichilemmal cyst, or proliferating trichilemmal cyst in the scalp. RESULTS: The authors discovered 17 cases, 13 were women, the average age was 54.9 years, all the tumors affecting the scalp, and just 3 cases were reported as malignant. CONCLUSION: In comparison with the existing data, the authors can observe that most of their patients were women and the scalp is the most affected area. Most did not present associated symptoms. As the authors can see, most are benign and long-lasting: however, the authors cannot ignore that a small percentage can be malignant.

Rapid malignant transformation of an intracranial epidermoid cyst: Report of a case.

Intracranial epidermoid cysts (ECs) occur at various locations along the neuraxis and account for nearly 2% of all intracranial tumors. Considering the frequency of ECs, transformation of ECs into squamous cell carcinomas is a rare occurrence. Here, we report the case of a 39-year-old man who presented with a lesion in the left cerebellopontine angle and underwent gross total resection for the same. Histopathological examination revealed a benign EC with mild chronic inflammation. Five months later, the patient presented with another lesion at the same location with evidence of brainstem bleed. Histopathological examination revealed a moderately differentiated squamous cell carcinoma and remnants of the previous cyst in the form of lamellated keratin, indicating malignant transformation of the EC.

Nonneoplastic and noninfective cysts of the central nervous system: A histopathological study.

Nonneoplastic epithelial cysts involving the central nervous system are diverse and are predominantly developmental in origin. This study represents a surgical series describing the histopathological features of 507 such epithelial cysts with clinical and imaging correlation. Age at surgery ranged from 7 months to 72 years (mean: 33 years) affecting 246 male and 261 female patients. Colloid cyst was the most frequently resected cyst, followed by epidermoid cyst, arachnoid cyst, Rathke cleft cyst, dermoid cyst, neurenteric cyst, Tarlov cyst, and choroid plexus cyst. Diagnosis was based on the location of the cysts and the nature of the lining epithelium. Rathke cleft cyst showed the highest propensity for squamous metaplasia, significant inflammation, and xanthogranulomatous reaction. Ulceration of lining epithelium and calcification were most frequent in dermoid cyst. Radiopathological concordance was maximal for colloid cyst, followed by epidermoid and arachnoid cysts. Epidermoid and dermoid cysts exhibited the highest propensity for local tumor progression, followed by Rathke cleft cyst.