Cellular Schwannoma Research Articles

Clinicopathological differences between classical schwannomas and cellular schwannomas in the retroperitoneum.

This study aimed to compare clinical and pathological features of retroperitoneal classical schwannomas and cellular schwannomas. A total of 64 cases of retroperitoneal classical schwannoma and 48 cases of cellular schwannoma were studied. Histopathological analysis was performed using hematoxylin and eosin staining and immunohistochemistry. Retroperitoneal cellular schwannomas exhibited 100% (48/48) and 75% (36/48) positive expression for glial fibrillary acidic protein (GFAP) and cytokeratins (CK), respectively. Classical schwannomas showed rates of 6.25% (4/64) and 15.63% (10/64), respectively (P < .05). In classic schwannomas, 85.9% (55/64) showed a reticular pattern of positive anti-CD34 staining around tumor margins and subcapsular areas vs 52.1% (25/48) in cellular schwannomas (P < .05). Cellular schwannomas exhibited more mitotic figures than classical schwannoma (P < .05). The recurrence rate of cellular schwannomas was 10.42% (5/48), while that of classical schwannomas was 1.56% (1/64) (P < .05). Retroperitoneal cellular schwannomas commonly express GFAP and CK compared to classical schwannomas, suggesting that cellular schwannoma may originate from unmyelinated Schwann cells, while classical schwannoma may originate from myelinated Schwann cells. Anti-CD34 staining patterns may be used to distinguish between the 2 types. Retroperitoneal cellular schwannomas also show higher mitotic activity and are more prone to recurrence.

Long-term postoperative outcomes of spinal cellular schwannoma: study of 93 consecutive cases

BACKGROUND CONTEXTCellular schwannoma (CS) is a rare tumor that accounts for 2.8%–5.2% of all benign schwannomas. There is a dearth of up-to-date information on spinal CS in the literature. PURPOSEThe aims of this study were to identify the proportion of CS cases amongst spinal benign schwannoma, describe the clinical features of spinal CS, and identify prognostic factors for local recurrence by analyzing data from 93 consecutive CS cases. STUDY DESIGNRetrospective review. PATIENT SAMPLEWe analyzed 93 PSGCT screened from 1,706 patients with spine CS who were treated at our institute between 2008 and 2021. OUTCOME MEASURESDemographic, radiographic, operative and postoperative data were recorded and analyzed. METHODSWe compared the clinical features of spinal CS from the cervical, thoracic, lumbar and sacral segments. Prognostic factors for local recurrence-free survival (RFS) were identified by the Kaplan-Meier method. Factors with p≤.05 in univariate analysis were subjected to multivariate analysis by Cox regression analysis. RESULTSThe proportion of spinal CS in all benign schwannomas was 6.7%. The mean and median follow-up times for the 93 patients in this study were 92.2 and 91.0 months respectively (range 36–182 months). Local recurrence was detected in 11 cases, giving an overall recurrence rate of 11.7%, with one patient death. Statistical analysis revealed that tumor size ≥5 cm, intralesional resection, and Ki-67 ≥5% were independent negative prognostic factors for RFS in spinal CS. CONCLUSIONSWhenever possible, en bloc resection is recommended for spinal CS. Long-term follow-up should be carried out for patients with tumor size ≥5 cm and postoperative pathological Ki-67 ≥5%.

P28 Congenital Cellular Plexiform Schwannoma Masquerading as Infantile Haemangioma – A Case Report

Abstract Introduction Schwannomas are tumours of the peripheral nerve sheath that rarely metastasize but are prone to recurrence. They sometimes occur in the context of syndromes such as neurofibromatosis type 2, Carney complex, and schwannomatosis. Congenital schwannomas appear as an erythematous patch that increases in size in the first few weeks and can be easily mistaken for infantile haemangioma (IH). Case A 3-month-old boy was referred to us for suspected IH on the dorsum of his right hand. At birth, he had a slightly erythematous patch but was rapidly increasing in size. Initial ultrasound done locally suggested it may be an IH based on the demonstration of arterial and venous flows. He was otherwise well, and there were no concerns about his growth or development. On examination, he had a firm mass, measuring 3 cm in diameter, that was not clinically in keeping with a vascular anomaly. Our repeated ultrasound showed a solid tumour, possibly fibrosarcoma or myofibroma. Biopsy confirmed cellular plexiform schwannoma and he underwent excision. The results of whole genome sequencing are pending (SMARC-1 and NF), and he remains under the care of the oncology team. Conclusion Clinicians assessing infants with “haemangiomas” have a difficult task of differentiating them from other soft tissue tumours. The clinical appearance of vascularity, along with high vascular flow seen on the imaging, cannot always rule out soft tissue tumours. Assessment of firmness can be somewhat subjective, but any vascular lesion that is very firm should be investigated further.

Adrenal Schwannoma Treated with Laparoscopic Adrenalectomy: A Case Report and Literature Review

Adrenal schwannoma (AS) is extremely rare. We report on a 36-year-old female patient who presented with right upper abdominal pain. Preoperative computed tomography (CT) showed a 5-cm right adrenal mass. The metabolic work-up was normal. She underwent laparoscopic right adrenalectomy without complications. Microscopy and immunohistochemistry demonstrated a cellular schwannoma. One year after surgery, the patient was fine and without clinical recurrence or metastasis. Usually, the pre-operative diagnosis of AS is challenging and pathologic examination with immunohistochemistry is the only way to make a definite diagnosis.

Spinal Cellular Schwannoma: A Case Report of Acute Post-Traumatic Paralysis

This case report describes a 64-year-old female patient who presented to the emergency department with lower back pain, bilateral leg pain, and numbness. Magnetic resonance imaging revealed a mass-like lesion at the L2 level, which was surgically removed and was found to be a cellular schwannoma upon histopathological examination. The patient exhibited immediate postoperative improvement and was referred for rehabilitation. This case highlights the importance of considering cellular schwannoma as a possible diagnosis in patients with intradural extramedullary tumors causing compressive symptoms.

A Spectrum of Histomorphological and Immunohistochemical Expression Profiles of S-100, CD56 and Calretinin in Benign Peripheral Nerve Sheath Tumours.

Peripheral nerve sheath tumours comprise benign tumours; namely schwannomas and neurofibromas, and onlyrarely comprise hybrid benign tumours and their malignant counterpart, malignant peripheral nerve sheath tumours (MPNST). There may be diagnostic difficulties in histopathology analysis, especially in core needle biopsies where there is a limited amount of tissue. Immunohistochemistry (IHC) can play a beneficial role, especially in atypical and cellular histological variants and rarely hybrid tumours. A total of 45 cases of benign peripheral nerve sheath tumours were included in the study; there were 27 cases of neurofibroma including variants like plexiform and cellular neurofibromas and 18 cases of schwannomas including variants like ancient schwannoma and cellular schwannoma. Immunohistochemical staining (IHC) on these tumour tissues using S-100, CD56 and calretinin was done and scoring was done based on extent and intensity. No significant differences were observed between neurofibromas and schwannomas on patient age and anatomical locations of these tumours. IHC results did not show statistically significant patterns of expression of S-100 protein between the schwannoma and neurofibromas groups (p=0.75).CD56 protein was expressed strongly (3+) in90% of cases of schwannoma and negative in 86% of neurofibromas, the differential expression between the two groups was found to be statistically significant (p <0.0001). Calretinin was positive in 39% of schwannomas including one case of cellular schwannoma and negative in all (100%) cases of neurofibroma while the differential expression of calretinin between schwannoma and neurofibroma groups was found to be statistically significant (p < 0.005). Our study shows that S-100 does not show differential expression between schwannomas and neurofibromas. CD56 could be a potentially useful IHC marker to aid in the diagnosis of peripheral nerve sheath tumours with significantly higher expression in schwannomas compared to neurofibromas. Calretinin was also found to be preferentially expressed in schwannomas, though the difference is statistically significantly lower compared to CD56.A panel of all these markers could be used for accurate diagnosis.

An unusual diffuse CD34 staining in an olfactory groove cellular schwannoma: Case report

Background: Intracranial schwannomas are benign lesions, expected to exhibit characteristic ultrastructural features and immunophenotypic profile, typically being S-100, SOX10 and collagen-IV positive, while other markers, including CD34, are not usually expressed and are employed in the diagnostic elimination process. Case presentation: A 51-year-old female presented with a rapidly deteriorating neurological status. MRI showed a heterogeneous enhancing neoplasm of the anterior fossa. Preoperative differential diagnosis predilected an esthesioneuroblastoma. A bifrontal craniotomy with total excision of the lesion was performed. Dural infiltration was present. There was no association with the olfactory system. Microscopic examination revealed a uniform population of spindled to slightly epithelioid cellular proliferation with no significant atypia, low mitotic activity, and foci of necrosis. Upon immunohistochemical investigation the tumor was consistent with cellular schwannoma. Diffuse positivity for CD34 was an unusual finding. Discussion: Cellular schwannoma should be considered in the presence of an anterior fossa tumefaction. Olfactory nerve is not directly associated with these lesions. Various theories have been proposed, with the meningeal trigeminal branches’ origin being the most probable. The characteristic ultrastructural Antoni formations may be scarce or even absent in cellular schwannomas creating potential diagnostic difficulties. Unusual diffuse CD34 positivity should not be employed for excluding the diagnosis.

Comparison study of clinicopathological features of cellular schwannoma between retroperitoneum and other sites.

Cellular schwannoma (CS) is a relatively rare neural tumor with few reports. This study aimed to compare the clinicopathological characteristics of CS in the retroperitoneum and other sites by analyzing the hematoxylin-eosin (HE) staining and immunohistochemical (IHC) staining results, to provide some help for pathological diagnosis. A total of 79 CS cases from the Department of Pathology, Peking University International Hospital were collected, and the diagnosis was based on the 5th WHO classification of soft tissue tumors. The staining results of HE and IHC were judged and analyzed according to the instructions. The t-tests, Chi-square test and Fisher's exact probability test were used for statistical analysis. Compared with other sites, the volume of retroperitoneal CS tumors were larger (t=4.265, P=0.001) and more likely to recur (χ2=4.223, P=0.04). Nerve sheath structures were rare around the tumors (χ2=60.096, P=0.000). Immunohistochemically, there was a difference in the expression of glial fibrillary acidic protein (GFAP), Cytokeratin (CK), and myelin basic protein (MBP) between the two groups (χ2=54.290, P=0.000; χ2=4.879, P=0.027; χ2=31.792, P=0.000). But there was no difference in expression between the two groups in the other indexes. It founded that Retroperitoneal CS was often positive for GFAP and CK, suggesting it originated from unmyelinated Schwann cells. CS in other sites, the expression of GFAP and CK was often negative, indicating they derived from myelinated Schwann cells. The expression of MBP in the peripheral nerve sheath structure of CS can be used to determine whether the tumor originates from myelinated or unmyelinated Schwann cells. These findings may provide a reference for revealing pathogenesis, diagnosis and evaluating prognosis of CS.

Cellular schwannoma of the posterior tongue: a rare case report with a literature review

Introduction: Schwannoma is a gradually growing encapsulated benign tumor arising from the Schwan cells of the peripheral nerve sheath. This study aims to report a rare case of tongue cellular schwannoma. Case presentation: A 15-year-old boy presented with a swelling of the posterior part of the tongue that had started 2 years prior. On examination, a large mass was seen in the posterior part of the tongue. It was smooth, mobile, and nontender on palpation. A contrast computed tomography scan of the neck revealed an irregular, ill-defined, thick-walled cystic lesion. Magnetic resonance imaging demonstrated a well-circumscribed, enhancing mass measuring about 5×4.56×4.59 cm and causing compression upon the oropharyngeal airway. Histopathologic examination revealed a cellular schwannoma. Discussion: Histologically, all schwannoma tumors are encapsulated. Under the capsule, there are 2 specific patterns associated together, but they can be easily differentiated from each other. The first one is made up of firmly aggregated Schwan cells arranged in rows with palisade and enlarged nuclei which are known as Antoni type-A. The second one is the Antoni type-B that consists of weakly packed Schwann cells. Conclusion: Tongue schwannoma is regarded as a solitary encapsulated benign tumor that may cause complications like difficulty in phonation. The primary treatment modality usually is transoral excision.

FDG PET/CT in a Case With Cellular Schwannoma of the Kidney.

Schwannoma of the kidney is exceedingly rare. We describe contrast-enhanced CT and FDG PET/CT findings in a case with renal cellular schwannoma. Contrast-enhanced CT showed the enhancing tumor was located in the anterior middle portion of the left kidney, encasing the renal vessels and compressing the renal pelvis. The tumor showed inhomogeneous FDG uptake with SUV max of 8.6 mimicking renal cell carcinoma. This case indicates renal schwannoma should be included in the differential diagnosis of FDG-avid renal lesions.

Sarcomatoid Lesions of Head and Neck Region: A Diagnostic Dilemma

One challenging feature of head and neck pathology is that a dizzying array of sarcomatoid lesions occurs here ranging all the way from reactive to malignant and very aggressive. This makes accurate diagnosis critical. These lesions are quite diverse with great clinical and biological heterogeneity. Some are malignant while many others are benign or simply reactive in nature. For example; at mucosal sites, a well known lesion is spindle cell carcinoma (SpCC), which are overtly malignant, and the differential diagnosis then includes a number of different malignant spindle cell lesions. However, there are several benign or even non-neoplastic lesions that can sometimes be difficult to discern from SpCC, e.g. Nodular fasciitis, Proliferative myositis, Cellular schwannoma, Benign fibrous histiocytoma, Carcino sarcoma, Sarcomatoid melanoma. Fracture callus, etc.&#x0D; Aim of Study: There is a diagnostic challenge to the oral pathologists to differentiate dizzying array of sarcoma like lesions from other similar microscopic simulates ranging all the way from reactive to malignant and very aggressive. This article aims to review the sarcomatoid lesions of the head and neck region with emphasis on differential diagnosis histologically and immunohistochemicaly.

Vestibular Schwannomas in Young Patients: A 12-Year Experience in a Single Center

This study evaluated the characteristics of vestibular schwannomas (VS) in young patients, including clinical features, treatment, prognosis, and histopathologic characteristics. We retrospectively reviewed medical records and follow-up data for 36 pediatric patients <21 years of age who were surgically treated for VS in the Chinese PLA General Hospital between 2008 and2019. Mean patient age was 17.4 years. Mean tumor size was 2.8 cm. Hearing loss (n= 32, 88.9%) and tinnitus (n= 20, 55.6%) were the most common symptoms. Ten patients (27.8%) had impaired facial nerve function after surgery. Gross total resection (GTR) was achieved in 26 cases (72.2%). The median tumor Ki-67 level was 5%. Tumor size was related to incomplete tumor resection (odds ratio, 0.2; 95% confidence interval, 0.1-0.9) and postoperative facial nerve dysfunction (odds ratio, 24.9; 95% confidence interval, 1.2-539.1). Tumor size was nonlinearly associated with prognosis and 2.2 cm corresponded to the inflection point at which the probability of tumor remnant and postoperative facial nerve dysfunction significantly increased. The GTR and low Ki-67 groups achieved better 3-year tumor control rate. Histopathologic findings confirmed the presence of cellular schwannoma subtype in young patients. Tumor size is an important factor affecting the prognosis of VS in young patients. For large VS, surgical treatment should be the first choice, rather than wait-and-scan. VS in young patients shows high tumor proliferation and a tendency to relapse. The cellular schwannoma subtype requires special attention; an accurate histopathologic diagnosis is necessary for young patients with VS, and a closer follow-up strategy should be adopted for cellular VS.

Plexiform Cellular Schwannoma in Infancy and Childhood: A Clinicopathological Study of Seven Cases of an Underrecognized Nerve Sheath Tumor with a Tendency Toward Local Recurrence

Plexiform cellular schwannoma (PCS) is very rare, and it is not completely understood. We present our experience with 7 additional cases of PCS in infancy and childhood to further characterize its distinctive clinicopathological features. There were 5 females and 2 males with a mean age of 28 months (ranging, 2 months to 8 years). The involved sites included the left forearm (n = 2), sacrococcygeal region (n = 2), retroperitoneum (n = 1), thoracic spinal canal and thoracic cavity (n = 1), and neck (n = 1). Tumor sizes ranged from 3 to 13 cm in maximum diameter (mean, 7.1 cm). Histologically, all tumors consisted of abundant spindle cells arranged in a multinodular or plexiform growth pattern, possessing elongated, hyperchromatic nuclei and pale eosinophilic cytoplasm with indistinct cell margins. Mitotic figures were easily identified, with a mean count of 4 per 10 consecutive high power fields (HPF). Immunohistochemically, all tumors were strongly and diffusely positive for S100 protein, SOX10 and H3K27me3. The Ki-67 index ranged from 5% to 30% (mean, 15%). Follow-up (available in 6 cases) revealed that 5 patients experienced local recurrence and were treated by re-excision. There was no evidence of recurrence and metastasis in 3 patients, and the other 2 were alive with the disease. In conclusion, PCS is an uncommon nerve sheath tumor predominantly occurring in infants and children, featuring a plexiform or multinodular growth pattern and exhibiting a tendency toward local recurrence. PCS is easily mistaken as malignant peripheral nerve sheath tumor (MPNST) due to its locally aggressive behaviors and worrisome features, including hypercellularity, hyperchromatism and high proliferative activity. Increased awareness of its potential occurrence and greater familiarity with its characteristic features are helpful for both clinicians and pathologists to avoid misdiagnosis and unnecessary overtreatment.

Schwannoma of the abdominal wall: updated literature review

Summary Background Schwannoma is a benign tumor arising from Schwann cells of the peripheral nerves. It is often asymptomatic and can develop in the retroperitoneum, mediastinum, head and neck region, and upper and lower extremities. Schwannoma of the abdominal wall is extremely rare, but differential diagnosis with malignant neoplasms is important to reduce the risk of undertreatment. Methods A narrative review of abdominal wall schwannoma was performed using PubMed, EMBASE, and Web of Science database and the search terms “schwannoma”, “neurinoma”, “neurilemmoma”, “soft tissue tumors”, “neurogenic tumor”, “rectus abdominis mass”, “abdominal wall”. In addition, the hospital charts were reviewed to report the personal experience. Results Only 9 single case-reports of benign schwannoma of the abdominal wall were found in the English medical literature over the past decade. None of the patients received preoperative biopsy and all were resected with clear margins. In addition to the literature review, we report the case of a 58-year-old man referred for a palpable mass in the left upper abdominal quadrant. Ultrasonography and magnetic resonance imaging revealed a solid and well-encapsulated mass inside the left rectus abdominis muscle. A core biopsy of the lesion provided the diagnosis of cellular schwannoma and this was confirmed by histopathologic examination of the surgical specimen. Conclusions Benign schwannoma of the abdominal wall is extremely rare. Percutaneous core needle biopsy is important for the differential diagnosis with more common and biologically more aggressive malignancies, such as desmoid tumors and sarcomas, and may be relevant for planning the most appropriate management.

Comparison of pathological, radiological, and prognostic features between cellular schwannoma and non-cellular schwannoma

PurposeTo investigate the differences of pathological, radiological, and prognostic features between cellular schwannoma (CS) and non-cellular schwannoma (NCS). MethodsCT and MRI images of 24 patients with CSs and 30 patients with NCSs were reviewed retrospectively. Clinico-pathological characteristics of CSs and NCSs and tumor radiological features including location, shape, size, border, cystic-solid components, hemorrhage, calcification, bone remodeling, pattern of CT/MRI precontrast scan, degree of enhancement, target sign, and tumor vessels were recorded. Statistical analyses were performed with Chi square or Fisher’s exact test, independent sample t test, and logistic regression analysis to compare the differences between CSs and NCSs. ResultsFour CSs showed mitotic activity, which was not found in the NCS group (P = 0.034). The CS group showed higher MIB-1 index than that in the NCS group (P = 0.002). Two patients with CS presented with tumor recurrence. Compared to NCSs, CSs were often located in spinal area (P = 0.028) and irregular (P = 0.013) with larger size (P = 0.005). Target sign, a common finding in NCSs (7/22, 31.8 %), was not seen in CSs (P = 0.014). The tumor vessels were only seen in CS group (4/22, 18.2 %; P = 0.027). Regression analysis revealed that location (P = 0.048) and size (P = 0.012) were independent indicators in differentiating CSs from NCSs. ConclusionsCS is a rare subtype of schwannoma with some significant radiological features including a predilection for the spinal area, irregular shape, large tumor size, absent target sign, tumor vessels, and potential risk of recurrence. Location and size of the schwannomas were the most useful indicators in differentiating CSs from NCSs.

Surgical Management of Giant Thoracic Paraspinal Schwannomas

Giant paraspinal thoracic schwannomas (GPTSs) are benign, slow-growing, encapsulated lesions. They can be intracanalicular, span more than 2 vertebral bodies, and/or have a foraminal component with extraspinal extension >2.5 cm. They pose surgical challenges because of the often unfamiliar complex regional anatomy. We report the largest series of GPTSs and discuss regional surgical strategies for tumors in the thoracic spine. We conducted a retrospective review of GPTSs operated at a national spinal referral center between December 2008 and October 2019. Inclusion criteria included World Health Organization grade 1 GPTS. Patient demographics, clinical features, radiology, and histopathology were assessed. Seventeen patients (12 females, 5 males) had a mean age of 48.1 years (range 21-65 years). Five GPTS (29%) were located at T1-T3, 6 (35%) at T4-6, and 6 (35%) below T6. The mean maximum diameter was 58.5 ± 19.1 mm (range 30-91 mm). Mean volume was 90.9 cm3 (range 19.1-350.6 cm3). Twelve (70%) had a fluorodeoxyglucose positron emission tomography scan showing low (25%) or moderate to high (75%) uptake. Six patients (35%) had preoperative computed tomography-guided biopsy. Surgical approaches included 1) manubriotomy and variations (4/17); 2) high lateral thoracotomy (4/17); 3) posterior parascapular (1/17); 4) standard lateral thoracotomy (3/16); 5) posterior/posterolateral (2/17); and 6) combined posterior and thoracotomy (3/17). All patients had gross total resection and were grade 1 cellular schwannomas. No recurrence at final follow-up (mean 36.1 months, range 8-130 months). A number of approaches are available to resect GPST in specific locations in the thoracic spine. Total resection is achievable despite complex regional anatomy, location, and tumor extension but often requires anterior or combined approaches.

Phrenic nerve schwannoma: an unusual cause of painless neck lump

Schwannoma (neurilemmoma) arising from the cervical phrenic nerve is a relatively rare tumour type. We describe a case of phrenic nerve schwannoma in the head and neck region in a patient who presented with a painless neck swelling. Analysis of aspiration was suggestive of benign nerve sheath tumour. A computed tomography scan was done to confirm the location and entity of the tumour. The patient was treated with complete excision of the tumour including the maternal nerve fibres. He developed right hemidiaphragm palsy postoperatively, which was treated conservatively. Postoperative immunohistochemistry examination established the diagnosis of cellular schwannoma. The case highlights the challenges associated with the diagnosis and management of cervical schwannoma.

Hemorrhage in long segment cervical schwannoma; case report and literature review.

Background: Although hemorrhages associated with cervical and thoracic intraspinal schwannomas are typically localized to the subarachnoid hemorrhages (SAH) or subdural hemorrhages (SDH) compartments, rare intratumoral bleeds may also occur.Methods: In the literature, we found and analyzed multiple factors for 13 cases (e.g., epidemiological, clinical, and pathological) of cervical schwannomas with intratumoral hemorrhages (ITH). We added the 14th case of a 35-year-old female with along segment cervical schwannoma with ITH who presented with acute quadriplegia and respiratory decompensation.Results: These 14 patients averaged 51.77 years of age, 60% were male, and the tumor involved 2.83 segments. The incidence of SAH and ITH was noted in five cases each, while SDH’s were very rare. The pathological characteristics were consistent with the diagnosis of cellular schwannomas with S-100 positivity. The clinical outcomes were good (100%) in all the cases, including the one presented (modified McCormick score III).Conclusion: Cervical schwannomas with ITH are rare, and the surgical outcomes in such patients are good-excellent (>90%). The histopathology is always of prime importance and decisive in establishing and confirming the etiology of such ITH.

Psödosarkomatöz Bir Antite Olarak Sellüler Schwannoma: Ayırıcı Tanıda Potansiyel Bir Tuzak

Klasik schwannomalar periferik sinir kılıfından köken alan iyi sınırlı benign tümörlerdir. Tüm schwannomaların yaklaşık %5 kadarını sellüler schwannomlar (SS) oluşturur. Fasiküler patern, yüksek sellülarite ve mitotik aktivite varlığı bazı vakalarda yanlış değerlendirme sonucu malign olarak tanı alabilir. Bursa Uludağ Üniversitesi ve Düzce Üniversitesi Tıp Fakültesi Patoloji Laboratuarı arşivlerindeki 16 SS olgusu yeniden değerlendirildi. En sık görülen yerleşim yeri paravertebral/paraspinöz bölge olup bunu mediasten, ekstremiteler, gövde, adrenal bez ve dil takip ediyordu. İmmünohistokimyasal boyama uygulanan 15 vakanın tamamında S100 ile kuvvetli pozitivite görüldü. Ki 67 ile boyanma düşük-orta seviyelerde olup sellüler alanlarda %25’e varan ki 67 proliferasyon indeksi mevcuttu. SS tanısı bazen zorlayıcı olabilir ve histopatolojik özelliklerinin bilinmesi olası yanlış tanı ve gereksiz tedavileri önlemek açısından önemlidir. Bu çalışmada iki merkezin arşivlerindeki SS olgularının klinikopatolojik özelliklerinin incelenmesi ve literatür ile karşılaştırılması amaçlanmıştır.

Intracranial cellular schwannomas: a clinicopathological study of 20 cases.

Cellular schwannoma is a specific subtype of schwannoma, prone to misinterpretation as a malignant neoplasm. Involvement of the intracranial compartment by these tumours is extremely rare. We aim to characterise this clinicopathological subgroup. We identified a total of 20 cellular schwannomas with predominant intracranial involvement. The mean age of the patients at the time of surgery was 37years (range=16-81), with a slight female predominance (1.5:1 ratio). The most common sites were the eighth (n=8) and fifth (n=6) cranial nerves. Three tumours involved the anterior cranial fossa/olfactory groove, and a single case involved the glossopharyngeal nerve. All tumours met established criteria for cellular schwannoma, and were composed of interlacing fascicles of spindle cells lacking Verocay bodies with minimal Antoni B pattern and variable chronic inflammation and foamy histiocytes. Rare findings included haemosiderin deposition (n=6), necrosis (n=4), brisk mitotic activity (>10 mitoses per 10 high-power fields) (n=2), focal epithelioid morphology (n=2), myxoid areas (n=2), neuroblastoma-like pattern (n=1) and granular cells (n=1). Immunohistochemical stains demonstrated expression of Schwann cell markers (S100 protein, SOX10, collagen IV) and preserved H3 K27 trimethylation in all cases tested. Fourteen patients had postoperative follow-up, ranging from 2months to 21years (mean=66months). In patients with follow-up, local recurrence/persistence developed in six cases; five tumours were initially incompletely resected. No metastatic disease or deaths were reported. Intracranial cellular schwannomas share morphological and immunophenotypical features with cellular schwannomas at others sites may demonstrate locally aggressive growth but appear to lack metastatic potential.