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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.
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 
•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.
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.
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.
An extremely rare rectal schwannoma was successfully treated using a TEM without compromising anorectal function.
TEM is a feasible approach for local excision of rectal tumors with low risk of malignancy.
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.
PMCID: PMC3942198  PMID: 24688535
Neuro-Oncology  2014;16(Suppl 5):v127.
Schwannomas are common benign tumors of the vestibular nerve, or arise from nerves within the spinal canal. Although benign, both Spinal schwannoma (SS) and vestibular schwannoma (VS) cause significant morbidities. The current treatment strategies for VS and SS include surgery or radiation with each treatment option having associated complications and side effects. The transcriptional landscape of schwannoma remains largely unknown. We interrogated the transcriptome by gene-expression array analysis of 49 schwannomas and seven normal control vestibular nerves to identify tumor-specific gene expression patterns. We identified over 4000 differentially expressed genes between control and schwannoma with network analysis uncovering proliferation and anti-apoptotic pathways previously not implicated in VS. Using several distinct clustering technologies, we could not reproducibly identify VS subtypes or significant differences between sporadic and germline NF2 associated schwannomas suggesting that VS comprises of a highly similar entity. We next performed a transcript analysis comparing VS to SS. Surprisingly; we identified few differential transcripts demonstrating that schwannoma maybe a homogenous entity. Current studies are focused on DNA methylation profiling and genome wide sequencing analysis. To date our group and others have identified that inactivating mutations in NF2 is the most recurrent aberration in schwannoma. The most recurrent activated pathway in schwannoma was over-expression of PI3K/AKT/mTOR signaling pathway, which is directly druggable and we evaluated this pathway for therapeutic targeting. Testing compounds BEZ235 and PKI-587, both novel dual inhibitors of PI3K and mTOR, attenuated tumor growth in a cell line model of schwannoma. Our In vitro findings demonstrated that pharmacological inhibition of the PI3K/AKT/mTOR pathway with next generation compounds lead to decreased cell viability, and increased cell death. Future work is testing these compounds in vivo using relevant cell lines and primary cultures of schwannoma. Our findings implicate that targeting the PI3K/AKT/mTOR pathway may serve as a potential treatment strategy.
PMCID: PMC4218275
5.  Ancient Schwannoma of Ansa Cervicalis: A Rare Clinical Entity and Review of the Literature 
Case Reports in Surgery  2015;2015:578467.
Ancient schwannoma is an uncommon variant of schwannoma, a benign tumor arising from the nerve sheath. It is reported to arise from any nerves except optic and olfactory. However, only six cases of ancient schwannomas arising from ansa cervicalis nerve have been reported to date in English literature. Proper preoperative evaluation is necessary to rule out other causes of neck mass such as thyroid lesions, lymphadenopathy, and carotid body tumor. We report a case of ancient schwannoma arising from the ansa cervicalis nerve. The origin of the lesion from ansa cervicalis was confirmed by intraoperative finding. Postoperative histopathological examination revealed degenerative changes including pleomorphism, cellular atypia, large nuclei with prominent nucleoli, and paucity of mitotic figures. Periphery of the mass showed nuclear palisading with characteristic verocay bodies. Immunohistochemical evaluation for S-100 showed diffuse positivity of the tumor cells, thereby confirming the diagnosis of schwannoma. We consider that schwannoma of cervical region can have origin from any nerve and should try to identify the origin pre- and intraoperatively. The postoperative complications depend on the nerve of origin and the precision of the surgery performed.
PMCID: PMC4618111  PMID: 26635990
6.  Schwannoma of the submandibular gland: a case report 
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.
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.
PMCID: PMC4082163  PMID: 24968763
Schwannoma; Neurilemmoma; Submandibular gland; Treatment; Benign tumor
7.  Sinonasal Tract Neurofibroma: A Clinicopathologic Series of 12 Cases with a Review of the Literature 
Head and Neck Pathology  2014;9(3):323-333.
Neurofibroma (NF), a benign peripheral nerve sheath tumor, is very uncommon in the sinonasal tract, with only a few reported cases in the English literature. Cases within the files of the authors’ institutions confined to the sinonasal tract were compared to cases reported in the English literature (Medline 1966–2014). The 12 patients included 6 females and 6 males, aged 26–75 years (mean 46.2 years). The patients usually presented clinically with a mass lesion (n = 11), obstruction (n = 4) or pain (n = 3), with an average symptom duration of 42.9 months. Two patients had neurofibromatosis (NF1). Tumors involved the nasal cavity alone (n = 8), maxillary sinus alone (n = 2), or mixed sites (n = 2), with a range of 0.4–4.1 cm (mean 2.2 cm). The tumors were circumscribed, composed of spindled to wavy cells with curvilinear nuclei set in a background of collagenized stroma and mast cells. Nuclear palisading and perivascular hyalinization were not seen. Mitoses were scant. Pleomorphism, necrosis and increased cellularity were absent. By immunohistochemistry, the lesional cells were S100 protein, SOX10 and NFP positive, while CD34 highlighted the perineurium. INI1 was intact, with strong nuclear expression in all cases. All patients had surgical excision without recurrence (mean follow-up 8.6 years). The principle differential diagnoses include schwannoma, perineurioma, fibromatosis, and solitary fibrous tumor. NF of the sinonasal tract occurs in middle-aged patients without a gender predilection, usually with non-specific symptoms present for a long duration. Tumors are relatively large (mean 2.2), and usually affect one site only. Surgery is curative, with only 16.7 % NF1 associated. S100 protein, SOX10 and NFP highlight the Schwann cells, with CD34 highlighting the perineural fibroblasts.
PMCID: PMC4542792  PMID: 25503638
Neurofibroma; Sinonasal tract; Peripheral nerve sheath tumor; NF1; Immunohistochemistry
8.  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.
PMCID: PMC4063616  PMID: 24959229
schwannoma; bone scalloping; noggin; bone morphogenetic protein
9.  A Rare Case of Optic Nerve Schwannoma: Case Report and Review of the Literature 
Cureus  null;7(4):e265.
Background and Importance: Schwannomas are typically benign tumors of the peripheral nervous system that originate from Schwann cells. It is well known that the optic nerves are myelinated by oligodendrocytes since their cell bodies arise centrally within the lateral geniculate nuclei. Because of this basic cellular anatomy, optic schwannomas should theoretically not exist. It is possible, however, these rare lesions stem from small sympathetic fibers that innervate the vasculature surrounding the optic nerve and its sheath.
Clinical Presentation: The patient is a 46-year-old male with a one-year history of progressive right eye blurry vision. To our knowledge, there are only five known reported case of an optic nerve schwannoma. Additionally, because of its medial position relative to the optic nerve and within the orbital apex, it is the first such case to be resected via an endoscopic endonasal approach. The lesion was subtotally resected because of its adherence and continuity with the optic nerve and the patient’s wish to preserve his vision. He was subsequently referred to radiation oncology for external beam radiation therapy.
Conclusion: Herein, we discuss the pertinent clinical findings of this rare lesion and review the literature relative to optic nerve and solitary orbital schwannomas.
PMCID: PMC4494577  PMID: 26180689
endoscopic endonasal; myelination; optic nerve; schwannoma
10.  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.
PMCID: PMC3424953  PMID: 22923909
Intraosseous schwannoma; mandible; neurilemmoma
11.  Adrenal Schwannomas: Rare Tumor of the Retroperitoneum 
Case Reports in Surgery  2015;2015:547287.
Schwannoma is a benign neurogenic tumor originating from Schwann cells. These produce the myelin sheath that covers peripheral nerves that are often affected. This latter localization is extremely rare, and only a few case reports can be found in the medical literature. Studies have shown that approximately 0.5% to 5% of schwannomas are retroperitoneal, constituting 0.2% of adrenal incidental tumors. These usually present as incidental findings, nonsecreting adrenal masses in asymptomatic patients. Diagnosis of a schwannoma is based on detection of spindle cells with Antoni A and Antoni B regions in histological sections and positive staining for S-100 protein by immunohistochemical analysis. We report a case of an incidentally identified during an abdominal ultrasound examination with schwannoma localized in the left adrenal gland.
PMCID: PMC4460231  PMID: 26101687
12.  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.
PMCID: PMC4110123  PMID: 25083375
cellular schwannoma; nasal cavity; sinuses; paranasal; intracranial
13.  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.
PMCID: PMC3892226  PMID: 24455054
14.  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.
PMCID: PMC3921522  PMID: 24574814
Laparoscopy; Schwannoma; Appendiceal neoplasms; Immunohistochemistry; Differential diagnosis; Gastrointestinal tract
15.  Intraosseous Schwannoma of the Petrous Apex 
Background and Importance Intraosseous schwannoma is a relatively rare clinical entity that typically arises in vertebral and mandibular bone. Intraosseous schwannoma located entirely within the petrous bone is exceedingly rare, and only two cases have been reported to date.
Clinical Presentation A 47-year-old Asian man was referred to our hospital with a chief complaint of double vision. Neurologic examination revealed left abducens nerve palsy. Radiologic imaging showed a 35-mm osteolytic expansive lesion located in the left petrous apex. We made a preoperative diagnosis of chondrosarcoma and performed surgical resection. Surgery was performed via a left subtemporal epidural approach with anterior petrosectomy. The histopathologic diagnosis of the tumor was schwannoma. Schwannoma arising from cranial nerves was excluded from intraoperative findings in conjunction with the results for cranial nerves, and intraosseous schwannoma was diagnosed. Postoperative course was uneventful, and abducens nerve palsy resolved immediately after surgery.
Conclusion The differential diagnosis of intraosseous schwannoma should be considered for an osteolytic mass lesion within the petrous apex. Subcapsular tumor removal was considered ideal in terms of preservation of the cranial nerves and vessels around the tumor.
PMCID: PMC4520976  PMID: 26251791
schwannoma; intraosseous; petrous apex; neurinoma
16.  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.
PMCID: PMC4214448  PMID: 25364457
schwannoma; magnetic resonance imaging; cystic mass; neurilemmoma; pancreas
17.  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.
PMCID: PMC1602204  PMID: 16947016
Dorsal dumb-bell melanotic schwannoma; Thoracic nerve sheath tumor; Spinal tumor; Carney syndrome
18.  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.
PMCID: PMC1602204  PMID: 16947016
Dorsal dumb-bell melanotic schwannoma; Thoracic nerve sheath tumor; Spinal tumor; Carney syndrome
19.  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.
PMCID: PMC4253220  PMID: 25478402
Retroperitoneal space; Schwann cells; Schwannoma; Von recklinghausen disease
20.  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.
PMCID: PMC2988920  PMID: 21103244
Schwannoma; Neurilemoma; Colon; Colon neoplasms; Immunohistochemistry; S-100 protein; Ki-67 antigen
21.  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
Rare disease
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.
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.
PMCID: PMC4259562  PMID: 25472470
Biopsy, Fine-Needle; Diagnosis; Neurilemmoma
22.  Scrotal extratesticular schwannoma: a case report and review of the literature 
BMC Urology  2014;14:32.
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.
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.
PMCID: PMC4030735  PMID: 24776090
Scrotal schwannoma; Diagnosis; Histopathology
23.  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.
PMCID: PMC3122997  PMID: 21716830
Intraosseous; mandible; schwannoma
24.  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.
PMCID: PMC4172938  PMID: 25276456
25.  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.
PMCID: PMC3884186  PMID: 24403879
Incidentaloma; Schwannoma; Adrenalectomy; Positron emission tomography-computed tomography

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