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1.  Expression of bone morphogenic protein in sinonasal inverted papilloma with new bone formation 
Allergy & Rhinology  2011;2(1):16-20.
Inverted papilloma (IP) is a common benign tumor in the nose and sinus. Osteogenesis in sinonasal IP is extremely rare; to date, only five cases of IP with new bone formation appear in the literature. In addition, the mechanism of osteogenesis in IP remains unclear. Here, we describe three cases of IP with new bone formation and an investigation into a possible role for bone morphogenic protein (BMP) in osteogenesis. Of three patients with sinonasal IP with new bone formation, two were treated by endoscopic sinus surgery and one was followed up with watchful waiting. Tumor tissues were subjected to immunohistochemistry to detect BMP expression. The patients were successfully treated surgically and showed no evidence of recurrence postoperatively. Follow-up examination is ongoing. Immunohistochemically, the tumors expressed BMP-4 but not BMP-2 or BMP-7. ESS could be successfully used to achieve complete removal of the sinonasal IPs with new bone formation. BMP-4 might be associated with new bone formation in the tumor.
doi:10.2500/ar.2011.2.0004
PMCID: PMC3390124  PMID: 22852110
Bone formation; bone morphogenic protein; endoscopic sinus surgery; inverted papilloma; sinonasal
2.  Local excision of rectal schwannoma using transanal endoscopic microsurgery: A case report 
Highlights
•Extremely rare rectal schwannoma was successfully treated by TEM.•Only 11 cases of anorectal schwannoma have been reported.•TEM is a feasible approach for local excision of rectal tumors.
INTRODUCTION
Schwannoma is a neoplasm originating from the neural crest cells (schwann cells) that form nerve sheaths. These tumors are thought to be benign with little risk of malignant transformation. They rarely affect the gastrointestinal tract, and primary rectal involvement is extremely rare. Until 2013, only 11 cases of anorectal schwannoma have been reported. Optimal surgical treatment of rectal schwannoma has not been established.
PRESENTATION OF CASE
We herein describe a 70-year-old woman with a submucosal tumor arising from the posterior wall of the rectum with features mimicking a gastrointestinal stromal tumor. After discussing the operative procedures and obtaining written informed consent, we attempted local excision of the tumor using a transanal endoscopic microsurgery (TEM). The tumor was proved to be S-100 positive schwannoma on immuhistochemical studies. Her postoperative course was uneventful, and there is no evidence of tumor recurrence as of 6 months after surgical excision.
DISCUSSION
An extremely rare rectal schwannoma was successfully treated using a TEM without compromising anorectal function.
CONCLUSION
TEM is a feasible approach for local excision of rectal tumors with low risk of malignancy.
doi:10.1016/j.ijscr.2014.11.020
PMCID: PMC4275951  PMID: 25437674
Transanal endoscopic microsurgery (TEM); Rectal shwannoma
3.  Clinicopathological and Immunohistochemical Characterisation of Gastric Schwannomas in 29 Cases 
Schwannomas are tumors arising from the nervous system that also occur infrequently in the gastrointestinal tract, most commonly in the stomach. This report characterizes 29 patients with benign or malignant gastric schwannomas. Surgical data and clinical follow-up information were available for 28 cases with a median postoperative duration of 57 months. Clinicopathological and immunohistochemical characteristics of benign and malignant schwannomas were analysed. Four cases (13.7%) were histologically diagnosed with malignant schwannoma. All tumors were positive for S-100 and CD56 proteins, displaying a diffuse staining pattern. Vimentin was expressed in 100% cases and all schwannomas were negative for smooth muscle actin, c-kit, and HMB-45. A significant difference was observed between the group of benign and malignant schwannomas as regards recurrences and metastasis after complete resection (P = 0.015). The survival time of patients with benign schwannomas was longer than the malignant group (P = 0.013), so gastric malignant schwannomas have a potential for recurrence and metastasis, with subsequently short survival. Complete resection with an attempt to remove all tumor tissue with negative margins is of paramount importance in the management of gastric schwannomas, particularly when they turn out to be malignant.
doi:10.1155/2014/202960
PMCID: PMC3942198  PMID: 24688535
4.  Schwannoma of the submandibular gland: a case report 
Introduction
Schwannoma is a benign, solitary, and slowly progressive encapsulated tumor originating from the sheath of myelinated nerve fibers. Schwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor. Here, we present an unusual case of a schwannoma of the submandibular gland in a 19-year-old man. Total excision of the submandibular gland resulted in complete resolution of symptoms with no cranial nerve deficits. The details of the histopathologic and immunohistochemical features are presented.
Case presentation
A 19-year-old Caucasian man was admitted to our clinic with a painless mass on the right side of his neck that he had had for the past four months. A neck examination revealed a smooth-surfaced, mobile, firm, and painless mass, 6cm in its greatest diameter, on the right side of the submandibular region. Fine-needle aspiration cytology was suggestive of a submandibular gland schwannoma. After the initial evaluation, our patient was prepared for surgical evaluation and resection with a presumptive diagnosis of a neurogenic tumor of the submandibular gland. The final diagnosis of schwannoma was verified by microscopic and immunohistochemical studies. At one-year follow-up of the case, there was no evidence of recurrence.
Conclusions
Schwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor. Our findings indicate good prognosis in an unusual case of a submandibular gland schwannoma in a 19-year-old man treated by surgical excision with no recurrence within 12 months of follow-up.
doi:10.1186/1752-1947-8-231
PMCID: PMC4082163  PMID: 24968763
Schwannoma; Neurilemmoma; Submandibular gland; Treatment; Benign tumor
5.  Expression of noggin, an antagonist of bone morphogenetic protein, in schwannoma: A possible mechanism 
Oncology Letters  2014;8(1):111-116.
Schwannoma is a benign peripheral nerve sheath tumor derived from Schwann cells. Bone scalloping, including spinal foramen enlargement, develops when the tumor is located adjacent to a bone and is a characteristic radiological feature. In the present study, to investigate the pathomechanism of bone resorption, the expression of noggin (a potent antagonist of bone morphogenetic protein) was analyzed in schwannoma tissues and compared with that observed in other soft tissue tumors. Quantitative polymerase chain reaction analysis revealed that the mRNA levels of noggin in schwannomas were significantly increased compared with the levels in other tumors. The gene product of noggin was only detected in a subset of schwannomas using immunohistochemistry and western blot analysis. Furthermore, the tissue extract from a noggin-producing schwannoma was found to inhibit osteoblastic differentiation in MC3T3 mouse osteoblastic cells in a dose-dependent manner. These findings indicate that bone scalloping in radiology may be induced by schwannoma-secreted noggin. In addition, noggin may have potential as a novel molecular and diagnostic marker for identifying certain types of schwannoma.
doi:10.3892/ol.2014.2138
PMCID: PMC4063616  PMID: 24959229
schwannoma; bone scalloping; noggin; bone morphogenetic protein
6.  Intraosseous schwannoma of the mandible 
Schwannomas (neurilemmomas) are slow-growing, benign neoplasms derived from schwann cells, the sheath cells that cover myelinated nerve fibers. These tumors most commonly arise in the soft tissues of the head and neck, as well as on the flexor surfaces of the upper and lower extremities. Intraoral lesions are uncommon, however, and intraosseous schwannomas are even rarer. In the Mayo Clinic series of 11,087 primary bone tumors, 14 cases of intraosseous schwannoma were identified, accounting for less than 1% of these benign primary bone tumors. The most common site of occurrence is the mandible, a characteristic traditionally attributed to the long intraosseous path of the inferior alveolar nerve. In this article, we describe an additional case occurring in the mandible of a 15-year-old boy.
doi:10.4103/0973-029X.99094
PMCID: PMC3424953  PMID: 22923909
Intraosseous schwannoma; mandible; neurilemmoma
7.  Atypical Presentation of Sinonasal Cellular Schwannoma: A Nonsolitary Mass with Osseous, Orbital, and Intracranial Invasion 
Objective Sinonasal cellular schwannoma represents < 4% of head and neck schwannomas. These benign tumors are typically confined to the nasal cavity or ethmoid sinus. We describe an atypical case of sinonasal cellular schwannoma with diffuse paranasal sinus involvement and both intraorbital and intracranial extension.
Results A 62-year-old woman presented with a 6-month history of right orbital proptosis and right-sided headache. Subsequent imaging revealed an invasive paranasal sinus mass extending through the skull base and displacing the right orbit. Preoperative biopsies were not diagnostic but revealed a spindle cell lesion suspicious for malignancy based on lack of encapsulation, infiltration of the sinonasal submucosa, and osseous invasion. The patient underwent open skull base surgery, and pathology confirmed a S100-positive nonencapsulated cellular schwannoma.
Conclusion An atypical case of sinonasal cellular schwannoma with intracranial extension is reported. Its presentation is contrary to the common view that these are isolated solitary lesions of the nasoethmoid region. We suggest that sinonasal cellular schwannoma be considered in the differential diagnosis of a poorly defined invasive paranasal sinus mass, particularly following biopsy.
doi:10.1055/s-0034-1376424
PMCID: PMC4110123  PMID: 25083375
cellular schwannoma; nasal cavity; sinuses; paranasal; intracranial
8.  Ancient Schwannoma of the hard palate. An uncommon case report and review 
Schwannoma or neurilemmoma is an infrequent benign tumor in the oral cavity that originates from the Schwann cells on the neural sheath of the peripheral nerves. Schwannomas are frequently located in the soft tissues of head and neck region, but only a 1 to 12% of them are located in the oral cavity. Some histological variants of schwannoma have been described including the cellular, plexiform, epithelioid, ancient, and melanocytic types. The “ancient schwannoma” is an uncommon variant of this tumor that shows specific histological characteristics, and is rare in the oral cavity with less than 15 cases described on the literature. Most of them were located in the tongue or in the floor of the mouth, being the hard palate an extremely rare localization. We present a new clinical case of an ancient schwannoma with a long time of evolution, arising from the nasopalatine nerve, and located in the hard palate of a 35 year old female. We also review the main clinical and histological characteristics of this pathology.
Key words:Ancient schwannoma, neurilemmoma, palate, schwannoma.
doi:10.4317/jced.50950
PMCID: PMC3892226  PMID: 24455054
9.  Bowel mesentery (meso-appendix) microcystic/reticular schwannoma: Case report and literature review 
Microcystic/reticular schwannoma is a recently described variant of schwannoma with a predilection for the gastrointestinal tract. Due to overlapping features with other tumors, unawareness of this tumor type may lead to diagnostic and therapeutic pitfalls. We here report a case of microcystic/reticular schwannoma arising in the meso-appendix of a 43-year-old woman. The tumor was incidentally discovered by computed tomography scan for unrelated reasons. A laparoscopic operation was performed shortly after admission. Histological examination revealed a circumscribed tumor with a striking microcystic and cribriform architecture. Immunohistochemically, the tumor cells were diffusely positive for S100 protein, glial fibrillary acid protein and protein gene product 9.5, which were consistent with a peripheral nerve sheath tumor. The patient remains well with no signs of recurrence at a 10-mo follow-up. To our knowledge, this is the first case of microcystic/reticular schwannoma arising in the meso-appendix. Albeit very rare, microcystic/reticular schwannoma should be included in the differential diagnosis of appendiceal tumors.
doi:10.3748/wjg.v20.i5.1371
PMCID: PMC3921522  PMID: 24574814
Laparoscopy; Schwannoma; Appendiceal neoplasms; Immunohistochemistry; Differential diagnosis; Gastrointestinal tract
10.  Pancreatic schwannoma: A case report and review of the literature 
Oncology Letters  2014;8(6):2741-2743.
Schwannoma or neurilemmoma is a well-defined, benign tumor, which arises from neural crest cells and surrounds the nerve sheath. It is rare neoplasm that is typically found in the extremities, such as the thorax, head, neck, pelvis and rectum. Schwannoma localized to the pancreas is particularly rare and only a limited number of cases have been reported in the literature to date. The present study reports the case of a 30-year-old male with pancreatic schwannoma presenting with weight loss and abdominal pain. Pancreatic schwannoma was diagnosed using magnetic resonance imaging and ultrasonography-guided biopsy, which was followed by a duodenopancreatectomy. Although pancreatic schwannomas are rare, they must be considered during the differential diagnoses of cystic pancreatic masses.
doi:10.3892/ol.2014.2578
PMCID: PMC4214448  PMID: 25364457
schwannoma; magnetic resonance imaging; cystic mass; neurilemmoma; pancreas
11.  Dorsal dumb-bell melanotic schwannoma operated on by posterior and anterior approach: case report and a review of the literature 
European Spine Journal  2006;15(Suppl 17):664-669.
The schwannomas are benign tumors originating from Schwann cells which constitute the nerve sheath. The dorsal pigmented type of schwannomas is relatively rare (Goldstein in Am J Med Genet 86:62–65, 2004; Kurtkaya-Yapicier in Histol Histopathol 18(3):925–934, 2003). There are two distinct types of melanotic schwannoma: the sporadic melanotic schwannomas and the psammomatous melanotic schwannomas of Carney complex. We report a case of a patient harboring a right dorsal dumb-bell melanotic schwannoma and left adrenal mass. The patient underwent a surgical procedure for en bloc total removal of the mass by a posterior and anterior approach. Histopathological examination revealed the diagnosis of melanotic schwannoma. At present, we have no reliable marker of histopathological malignancy of melanotic schwannoma so the follow-up period ought to continue for a period of more than 5 years. As the total removal of the melanotic neurinomas is mandatory to prevent possible malignant transformation of the tumor recurrence or regrowth, we believe that the posterior and trans-thoracic approach are the most suitable one for the dorsal dumb-bell schwannoma.
doi:10.1007/s00586-006-0205-x
PMCID: PMC1602204  PMID: 16947016
Dorsal dumb-bell melanotic schwannoma; Thoracic nerve sheath tumor; Spinal tumor; Carney syndrome
12.  Dorsal dumb-bell melanotic schwannoma operated on by posterior and anterior approach: case report and a review of the literature 
European Spine Journal  2006;15(Suppl 5):664-669.
The schwannomas are benign tumors originating from Schwann cells which constitute the nerve sheath. The dorsal pigmented type of schwannomas is relatively rare (Goldstein in Am J Med Genet 86:62–65, 2004; Kurtkaya-Yapicier in Histol Histopathol 18(3):925–934, 2003). There are two distinct types of melanotic schwannoma: the sporadic melanotic schwannomas and the psammomatous melanotic schwannomas of Carney complex. We report a case of a patient harboring a right dorsal dumb-bell melanotic schwannoma and left adrenal mass. The patient underwent a surgical procedure for en bloc total removal of the mass by a posterior and anterior approach. Histopathological examination revealed the diagnosis of melanotic schwannoma. At present, we have no reliable marker of histopathological malignancy of melanotic schwannoma so the follow-up period ought to continue for a period of more than 5 years. As the total removal of the melanotic neurinomas is mandatory to prevent possible malignant transformation of the tumor recurrence or regrowth, we believe that the posterior and trans-thoracic approach are the most suitable one for the dorsal dumb-bell schwannoma.
doi:10.1007/s00586-006-0205-x
PMCID: PMC1602204  PMID: 16947016
Dorsal dumb-bell melanotic schwannoma; Thoracic nerve sheath tumor; Spinal tumor; Carney syndrome
13.  Retroperitoneal Schwannoma: An Atypical Presentation 
Schwannoma is a rare tumour arising from Schwann cells in myelinated neural sheath of the nerves. They can arise in various places like head, neck, extremities, adrenal, retro peritoneum, psoas muscle. We here present a case of 33-year-old male who came with features of acute pancreatitis, with incidentally detected mass in presacral region on ultrasonography. Investigations like CECT and MRI were suggestive of neurofibroma, radical excision of the mass was done which showed solitary encapsulated tumour and cut sections showed areas of necrosis, and histopathologically it was proven as schwannoma. Most of the schwannoma’s are benign, but rarely malignant transformation can occur. It can be associated with von Recklinghausen disease. Benign tumours have excellent prognosis, malignant tumours can present at later date with metastasis after excision also. Radiology plays a key role in diagnosis and follows up. Treatment is radical excision of tumour; recurrence is most common and has to be carefully followed up.
doi:10.7860/JCDR/2014/9255.5013
PMCID: PMC4253220  PMID: 25478402
Retroperitoneal space; Schwann cells; Schwannoma; Von recklinghausen disease
14.  Schwannoma of the Colon 
Case Reports in Gastroenterology  2009;3(3):293-299.
Schwannomas are neoplasms originating from Schwann cells, which are the cells forming nerve sheaths. These neoplasms generally involve peripheral nerves. They rarely affect the gastrointestinal tract and primary colon involvement is extremely rare. The objective of the present paper was to present a case of primary schwannoma of the sigmoid colon, unassociated with von Recklinghausen disease, that was histopathologically confirmed by means of an immunohistochemical panel. The patient was a 71-year-old woman who had had rectal bleeding when evacuating, with pain and tenesmus, for 4 months. She underwent colonoscopy, which identified a raised submucous lesion of 2.8 cm in diameter, located in the sigmoid colon, 30 cm from the anal margin. During examination, loop polypectomy with lesion excision was performed. Histopathological evaluation showed that this was a tumor of stromal origin. Its resection margins were compromised by neoplasia, and colon resection by means of videolaparoscopy was indicated. Conventional histopathological examination using the hematoxylin-eosin technique suggested that the neoplasm was of mesenchymal origin. An immunohistochemical panel was run for etiological confirmation, using anti-CD34 antibodies, desmin, cytokeratins (AE1/AE3), cKit, chromogranin and S-100 protein. The panel showed intense immunoexpression of S-100 protein. Investigation of the proliferative activity rate using Ki-67 antibodies showed that there was a low rate of mitotic activity, thus confirming the diagnosis of primary benign schwannoma of the colon. The patient's postoperative evolution was uneventful and she remains in good health, without signs of tumor recurrence, 15 months after surgical excision.
doi:10.1159/000237736
PMCID: PMC2988920  PMID: 21103244
Schwannoma; Neurilemoma; Colon; Colon neoplasms; Immunohistochemistry; S-100 protein; Ki-67 antigen
15.  A Cervical Vagal Schwannoma Mimicking a Parathyroid Cyst 
Cervical vagal schwannomas with cystic degeneration changes are extremely rare. These tumors are typically benign and slow growing. A 44-year-old woman underwent complete resection of a tumor measuring 4×3.5 cm in the right neck using the endoscopic approach, instead of the conventional transcervical approach. We applied the new scarless neck surgery technique with an endoscopic unilateral axillo-breast approach. The tumor originated from the right vagus nerve, and was confirmed to be a vagal schwannoma pathologically. The patient has been followed up for 18 months postoperatively with no evidence of tumor recurrence or neurological deficit. We report an extremely rare vagal schwannoma with cystic degeneration that was removed by an endoscopic approach, along with a review of the relevant literature.
doi:10.3342/ceo.2014.7.2.153
PMCID: PMC4050091  PMID: 24917916
Cervical vagal schwannoma; Unilateral axillo-breast approach
16.  Microcystic/Reticular Schwannoma: Morphological Features Causing Diagnostic Dilemma on Fine-Needle Aspiration Cytology 
Patient: Male, 28
Final Diagnosis: Microcystic/reticular Schwannoma
Symptoms: Neck fullness • finger tingling and numbness
Medication: —
Clinical Procedure: Surgical resection
Specialty: Anatomic Pathology
Objective:
Rare disease
Background:
Schwannoma is a common, benign, peripheral nerve sheath tumor. Fine-needle aspiration (FNA) has been very useful for diagnosing classic Schwannoma. Recently, a new morphological variant, the so-called microcystic/reticular Schwannoma, has been recognized. Although histological features of microcystic/reticular Schwannoma have been described, there are no available reports on its FNA cytological appearance.
Case Report:
A 28-year-old male presented with right arm and finger tingling and numbness. Physical examination found a right lower neck mass. He underwent FNA, followed by needle core biopsy. A diagnosis of microcystic/reticular schwannoma was made. In this case report, we focused on the FNA diagnostic features, thoroughly searched the literature, and discussed relevant information for differential diagnosis.
Conclusions:
Unlike classic Schwannoma, microcystic/reticular variant has unique cytological features which can mimic those of several morphologically similar mass lesions, making the FNA interpretation more challenging. Cytopathologists should be aware of this new variant of Schwannoma when evaluating FNA cytology of mass lesions showing low-grade, paucicellular, and myxoid features.
doi:10.12659/AJCR.892196
PMCID: PMC4259562  PMID: 25472470
Biopsy, Fine-Needle; Diagnosis; Neurilemmoma
17.  A Solitary Malignant Schwannoma in the Choana and Nasal Septum 
Case Reports in Otolaryngology  2014;2014:202910.
Malignant schwannoma is an extremely rare tumor and the risk of malignant schwannoma increases in patients with von Recklinghausen's disease. Recently, we encountered a case of solitary malignant schwannoma in the choana and posterior nasal septum. Malignant schwannoma has not been previously reported in these locations. A 53-year-old man, who was immunologically healthy and showed no abnormal dermatological lesions, presented with a polypoid mass in the right nasal cavity and underwent endoscopic mass excision. The mass originated from the choana and the posterior portion of the right nasal septum. This mass was confirmed as a malignant schwannoma on histological examination and immunohistochemical staining. After endoscopic excision, postoperative adjuvant radiotherapy was administered, and there was no recurrence at 1 year after treatment. This case suggests that a solitary malignant schwannoma should be considered in the differential diagnosis of a mass in the posterior nasal cavity.
doi:10.1155/2014/202910
PMCID: PMC4172938  PMID: 25276456
18.  A case of a massive mandibular schwannoma 
Schwannoma, a benign nerve sheath tumor is relatively rare in occurrence and even rarer in sites, such as jaw bones. There are only 45 reported cases of intraosseous schwannoma of the jaws reported in the literature. We report a rare case of mandibular schwannoma in a 50-year-old Indian male. The clinical features resembled that of a residual cyst, fibro-osseous lesion or an odontogenic tumor/cyst. Radiological differential diagnoses of ameloblastoma or odontogenic keratocyst was made based on the findings of the orthopantomogram. The lesion was examined histopathologically and a final diagnosis of schwannoma arising from the inferior alveolar nerve was made. The aim of this report is to add information to the existing sparse literature on intraosseous schwannomas of the jaw.
doi:10.4103/0976-3147.80108
PMCID: PMC3122997  PMID: 21716830
Intraosseous; mandible; schwannoma
19.  A Rare Adrenal Incidentaloma: Adrenal Schwannoma 
Case Reports in Gastroenterology  2013;7(3):420-427.
Adrenal schwannoma is an extremely uncommon cause of incidentaloma. It originates from neural sheath Schwann cells of the adrenal gland. We report the case of a left adrenal schwannoma incidentally discovered in a 32-year-old woman during examination of bloated feeling and stomach ache. The patient was incidentally found to have a left adrenal mass of 9 cm on abdominal ultrasonography. Computed tomography (CT) of the abdomen and [18F] fluorodeoxyglucose positron emission tomography (PET) were also performed. Metabolic evaluation was unremarkable. Due to the large size of the tumor, left adrenalectomy was performed. The postoperative course was uneventful. Histological examination established the diagnosis of schwannoma. This diagnosis was supported by immunohistochemistry of S-100 and vimentin positivity. In conclusion, adrenal schwannoma is an extremely rare entity and can grow considerably in size. The present case report emphasizes that clinicians should be aware of the possibility of retroperitoneal schwannoma. Total excision of benign schwannoma is associated with a favorable outcome. To our knowledge, there are case reports of schwannoma with CT and magnetic resonance imaging findings in the literature, although this is the first schwannoma case with PET-CT imaging.
doi:10.1159/000355871
PMCID: PMC3884186  PMID: 24403879
Incidentaloma; Schwannoma; Adrenalectomy; Positron emission tomography-computed tomography
20.  Scrotal extratesticular schwannoma: a case report and review of the literature 
BMC Urology  2014;14:32.
Background
Schwannomas are tumours arising from Schwann cells, which sheath the peripheral nerves. Here, we report a rare case of left intrascrotal, extratesticular schwannoma. Although rare, scrotal localisation of schwannomas has been reported in male children, adult men, and elderly men. They are usually asymptomatic and are characterised by slow growth. Patients generally present with an intrascrotal mass that is not associated with pain or other clinical signs, and such cases are self-reported by most patients. Imaging modalities (such as ultrasonography, computed tomography, and magnetic resonance imaging) can be used to determine tumour size, exact localisation, and extension. However, the imaging findings of schwannoma are non-specific. Therefore, only complete surgical excision can result in diagnosis, based on histological and immunohistochemical analyses. If the tumour is not entirely removed, recurrences may develop, and, although malignant change is rare, this may occur, especially in patients with a long history of an untreated lesion. Thus, follow up examinations with clinical and imaging studies are recommended for scrotal schwannomas.
Case presentation
A 52-year-old man presented with a 3-year history of asymptomatic scrotal swelling. Physical examination revealed a palpable, painless, soft mass in the left hemiscrotum. After surgical removal of the mass, its histological features indicated schwannoma.
Conclusions
Schwannoma should be considered in cases of masses that are intrascrotal but extratesticular. Ultrasonography provides the best method of confirming the paratesticular localisation of the tumour, before surgical removal allows histopathological investigation and definitive diagnosis. Surgery is the standard therapeutic approach. To prevent recurrence, particular care should be taken to ensure complete excision. This case report includes a review of the literature on scrotal schwannomas.
doi:10.1186/1471-2490-14-32
PMCID: PMC4030735  PMID: 24776090
Scrotal schwannoma; Diagnosis; Histopathology
21.  Primary hepatic benign schwannoma 
Schwannoma is predominantly a benign neoplasm of the Schwann cells in the neural sheath of the peripheral nerves. Occurrence of schwannoma in parenchymatous organs, such as liver, is extremely rare. A 64-year-old man without neurofibromatosis was observed to have a space-occupying lesion of 23mm diameter in the liver during follow-up examination for a previously resected gastrointestinal stromal tumor (GIST) in the small intestine. He underwent lateral segmentectomy of the liver under a provisional diagnosis of hepatic metastatic recurrence of the GIST. Histological examination confirmed the diagnosis of a benign schwannoma, confirmed by characteristic pathological findings and positive immunoreactions with the neurogenic marker S-100 protein, but negative for c-kit, or CD34. The tumor was the smallest among the reported cases. When the primary hepatic schwannoma is small in size, preoperative clinical diagnosis is difficult. Therefore, this disease should be listed as differential diagnosis for liver tumor with clinically benign characteristics.
doi:10.4240/wjgs.v4.i3.73
PMCID: PMC3332224  PMID: 22530081
Liver; Schwannoma; Benign liver tumor
22.  Schwannoma of the rectum: A case report and literature review 
Schwannoma is a tumor originating from the Schwann cells. Gastrointestinal schwannomas are uncommon stromal tumors of the intestinal tract and, in particular, rectal schwannomas are extremely rare. In fact, it is well established that schwannomas appear more frequently in the stomach and in the small intestine, while location in the colon or in the rectum is uncommon. Reading the literature, only few cases of rectal schwannoma have been reported. Their diagnosis is confirmed by the immunohistochemical panel (S-100 protein). When these tumors are located in the colon and in the rectum, radical excision with wide margins is mandatory, due to their tendency to recur locally or become malignant, if left untreated. In the present study, we describe a case of a rectal schwannoma occured in a 72-year-old man, presented as a small polypoid lesion, which was successfully removed in toto by hot-biopsy, during the same endoscopy, due to the dimensons. No recurrence of the lesion was observed after 6 mo of follow-up.
doi:10.12998/wjcc.v1.i1.49
PMCID: PMC3845929  PMID: 24303463
Rectum; Schwannoma; Immunohistochemistry; S-100 protein; Treatment
23.  Descriptive epidemiology of vestibular schwannomas1 
Neuro-Oncology  2006;8(1):1-11.
Vestibular schwannomas, commonly termed acoustic neuromas, arise from the vestibular branch of the eighth cranial nerve (acoustic nerve) and are benign, slow-growing brain tumors that negatively impact patient quality of life. They are thought to account for the majority of intracranial nerve sheath tumors. To describe incidence rate patterns and trends of primary nerve sheath tumors of the brain/CNS and the subset of vestibular schwannomas in two population-based incidence registries, data were obtained from 11 Central Brain Tumor Registry of the United States (CBTRUS) collaborating state registries and the Los Angeles County Cancer Surveillance Program (LACCSP) (1975–1998). Average annual incidence rates were tabulated by age, gender, race, year, and region and were age-adjusted to the year 2000 U.S. standard population. Multiplicative Poisson regression models were used to compare trends in primary nerve sheath tumors of the brain/CNS overall and in subgroups, including vestibular schwannomas, controlling for age, gender, race, microscopic confirmation, and region. Join-point regression analysis was used to identify any sharp changes in incidence over time. The overall incidence of primary nerve sheath tumors of the brain/CNS was 1.1 per 100,000 person-years (CBTRUS, 1995–1999 and LACCSP, 1995–1998). The incidence of vestibular schwannomas was similar for both data sets: 0.6 per 100,000 person-years (CBTRUS, 1995–1999) and 0.8 per 100,000 person-years (LACCSP, 1995–1998). Moreover, the incidence of primary nerve sheath tumors of the brain/CNS overall (CBTRUS, 1985–1999 and LACCSP, 1975–1998) and of vestibular schwannomas (CBTRUS, 1992–1999 and LACCSP, 1992–1998) increased over time. However, the incidence of benign schwannomas in sites other than the acoustic nerve either decreased (CBTRUS, 1992–1999) or experienced no significant change (LACCSP, 1992–1998). While improvements in diagnosis and reporting may explain some of these trends, further consideration of potential etiologic factors may be warranted.
doi:10.1215/S1522851704001097
PMCID: PMC1871924  PMID: 16443943
acoustic neuroma; average annual percentage change; incidence trends; nerve sheath tumors; vestibular schwannoma
24.  Giant presacral schwannoma presenting with constipation: a case report 
Introduction
Schwannoma, otherwise known as a neurilemmoma, is a tumor arising from peripheral nerve sheaths. Although commonly noted in association with the eighth cranial nerve as intracranial acoustic neuroma, cases of schwannoma arising in other locations have been reported in the literature. These tumors usually cause symptoms as a result of their mass effect and, since they are benign, encapsulated and non-invasive tumors, complete surgical excision is considered curative.
Case presentation
We report the case of a 46-year-old Sri Lankan man who presented to our facility with recent onset of difficulty evacuating his bowels. He was noted to have a giant presacral schwannoma on magnetic resonance imaging scan. The mass was surgically excised with improvement of our patient’s symptoms. A subsequent histopathological examination confirmed the presence of a benign schwannoma.
Conclusions
Although schwannomas commonly occur in the extremities, a rare case of occurrence in the pelvis is reported here. Due to the limited space in the pelvis, the local mass effect may be the presenting feature of such a lesion and surgical excision is curative.
doi:10.1186/1752-1947-6-285
PMCID: PMC3443643  PMID: 22963756
25.  Intracranial nonvestibular neurinomas: Young neurosurgeons’ experience 
Background and Objectives:
Neurinoma arising from other than nonvestibular cranial nerves is less prevalent. Here we present our experiences regarding the clinical profile, investigations, microneurosurgical management, and the outcome of nonvestibular cranial nerve neurinomas.
Materials and Methods:
From January 2005 to December 2011, the recorded documents of operated nonvestibular intracranial neurinomas were retrospectively studied for clinical profile, investigations, microneurosurgical management, complications, follow-up, and outcomes.
Results:
The average follow-up was 24.5 months. Total number of cases was 30, with age ranging from 9 to 60 years. Sixteen cases were males and 14 were females. Nonvestibular cranial nerve schwannomas most commonly originated from trigeminal nerve followed by glossopharyngeal+/vagus nerve. There were three abducent nerve schwannomas that are very rare. There was no trochlear nerve schwannoma. Two glossopharyngeal+/vagus nerve schwannomas extended into the neck through jugular foramen and one extended into the upper cervical spinal canal. Involved nerve dysfunction was a common clinical feature except in trigeminal neurinomas where facial pain was a common feature. Aiming for no new neurodeficit, total resection of the tumor was done in 24 cases, and near-total resection or gross total resection or subtotal resection was done in 6 cases. Preoperative symptoms improved or disappeared in 25 cases. New persistent deficit occurred in 3 cases. Two patients died postoperatively. There was no recurrence of tumor till the last follow-up.
Conclusion:
Nonvestibular schwannomas are far less common, but curable benign lesions. Surgical approach to the skull base and craniovertebral junction is a often complex and lengthy procedure associated with chances of significant morbidity. But early diagnosis, proper investigations, and evaluation, along with appropriate decision making and surgical planning with microsurgical techniques are the essential factors that can result in optimum outcome.
doi:10.4103/0976-3147.133566
PMCID: PMC4078606  PMID: 25002761
Intracranial; microneurosurgical management; neurilemmomas; neurinomas; nonvestibular; schwannomas

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