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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., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Association of Neuropathologists, Inc.)

Nerve tumors in the retroperitoneal space are a rarity. Radical surgery according to soft tissue tumors can lead to persistent pain and neurological deficits. This study aims to evaluate clinical outcomes of patients treated by a visceral- / neurosurgical approach. 33 patients with a retroperitoneal nerve tumor underwent surgery between 01/2002 and 12/2022 at our department. A visceral surgeon provided access to the retroperitoneal space, followed by micro-neurosurgical tumor preparation under neuromonitoring. Clinical examination and MRI were performed 12 weeks after surgery and further 3 months (WHO grade > 1) or 12 months (WHO grade 1). Further examinations were based on MRI findings and residual symptoms with median follow-up time of 24 months. One patient was treated for two distinct masses resulting in a total of 34 histological findings. Schwannomas (n = 15; 44.1%) and neurofibromas (n = 10; 29.4%) were the most common tumors. Long-term improvements were noted in radicular pain (15/18 patients; 83.3%), motor deficits (7/16 patients; 43.8%), abdominal discomfort and pain (5/7 patients; 71.4%). Recurrences were observed in 3/33 (9,1%) patients. This study represents the largest series of retroperitoneal BPNSTs treated with microsurgical techniques. Prospective multicenter studies are warranted to establish standardized treatment guidelines., (© 2024. The Author(s).)

Background: Schwannomas in the renal hilum are rare among retroperitoneal tumors. However, the possibility of malignant findings cannot be ruled out, and surgery is often indicated. This case was expected to be difficult to remove laparoscopically because the tumor was sandwiched between the arteriovenous veins of the renal portal. Sometimes, the tumor should be resected with a conservative approach to the kidney to preserve the renal function., Case Presentation: Our patient was a 51-year-old Asian-Japanese man who was referred to our department for a retroperitoneal tumor in the renal hilum. Since malignancy could not be ruled out due to its size (45 × 48 × 55 mm) on imaging, the tumor was excised laparoscopically. Histopathology revealed schwannoma., Conclusions: We herein report a case in which a renal hilar tumor between renal arteriovenous vessels was successfully resected laparoscopically., (© 2024. The Author(s).)

Background: Schwannomas are benign usually encapsulated nerve sheath tumors derived from the Schwann cells, and affecting single or multiple nerves. The tumors commonly arise from the cranial nerves as acoustic neurinomas but they are extremely rare in the pelvis and the retroperitoneal area. Retroperitoneal pelvic schwannomas often present with non-specific symptoms leading to misdiagnosis and prolonged morbidity., Case Presentation: We report the case of a 59-year-old woman presenting with a feeling of heaviness in the lower abdomen who was found to have a retroperitoneal pelvic schwannoma originating from the right femoral nerve. She had a history of two resections of peripheral schwannomas at four different sites of limbs. After conducting magnetic resonance imaging, this pelvic schwannoma was misdiagnosed as a gynecological malignancy. The tumor was successfully removed by laparoscopic surgery. Pathological analysis of the mass revealed a benign schwannoma of the femoral nerve sheath with demonstrating strong, diffuse positivity for S-100 protein., Conclusions: Although retroperitoneal pelvic schwannoma is rare, it should be considered in the differential diagnosis of pelvic masses, especially in patients with a history of neurogenic mass or the presence of neurogenic mass elsewhere., (© 2024. The Author(s).)

Introduction: schwannomas are benign and common soft tissue tumors. They are usually asymptomatic and are discovered for other reasons., Materials: we present the case of an 82-year-old male patient with a recent diagnosis of moderately differentiated adenocarcinoma of the colon and a hypermetabolic periaortic nodule as an incidental finding., Results: percutaneous biopsy of the periaortic nodule confirmed the diagnosis of schwannoma. At one year of follow-up, growth of the schwannoma has been demonstrated. There are no signs of progression of his oncological disease., Conclusions: schwannomas are benign tumors, rarely found in the retroperitoneum and can be sources of false-positive positron emission tomography results., (Universidad Nacional de Córdoba)

BACKGROUND Neurilemmomas are rare tumors derived from the Schwann cells that comprise the peripheral nerve sheaths. They have a slow growth and rarely display malignancy. Early diagnosis is rare, and the treatment consists by surgical resection. Although robotic-assisted surgery is commonly used for treating retroperitoneal diseases, there are few reports of resection of retroperitoneal and pelvic schwannoma through robotic-assisted surgery. In the present study, we reported a case of complete excision of a benign retroperitoneal schwannoma of the obturator nerve by robotic-assisted surgery. CASE REPORT A 51-year-old woman was referred by her gynecologist for left pelvic discomfort of a 3-month duration. The physical examination was normal, but a computerized tomography scan of the abdomen and pelvis showed an expansive pelvic lesion in the topography of the left iliac vessels, a hypodense contrast enhancement measuring 4.6×3.4 cm. Magnetic resonance imaging showed an extraperitoneal lesion located medially and inferiorly to the left external iliac vessels, with a size of 4.9×3.7 cm, and of probable neural etiology. Surgical resection of the tumor was recommended because of the diagnostic hypothesis of obturator nerve schwannoma. CONCLUSIONS This case showed that retroperitoneal neurilemmomas are difficult to diagnose owing to a lack of specific symptoms, and the best treatment is complete tumor resection. The use of robotic techniques gives greater dexterity to the surgeon, since it provides high-definition 3-dimensional vision, which can make the removal of retroperitoneal tumors susceptible to minimally invasive resection in a safe and effective way.

Schwannomas are benign, generally indolent tumors of neural crest origin and comprise the most common histologic tumor of peripheral nerves. Schwannomas are a rare histology for retroperitoneal tumors and very rare histologic findings for tumors of the adrenal gland with fewer than 50 cases in the reported literature. Here we present a case report of a non-hormonally functional but metabolically active adrenal tumor with indeterminate imaging characteristics with final pathology showing a 6.1 cm adrenal schwannoma as well as historical institutional pathology review revealing two additional cases., (© 2023. BioMed Central Ltd., part of Springer Nature.)

BACKGROUND Schwannomas are benign tumors and their appearance in the pelvic region is rare and poses a major diagnostic problem. They can be sporadic or associated with genetical syndromes. They have a slow growth rate and may be asymptomatic for many years. Symptoms are usually nonspecific and due to compression of adjacent structures. Abdominal imaging modalities may not be able to differentiate a benign schwannoma from a malignant retroperitoneal tumor. This report is of a case of a 68-year-old woman presenting with recurrent abdominal pain and a diagnosis of a presacral retroperitoneal benign schwannoma that mimicked an ovarian tumor on pelvic magnetic resonance imaging. CASE REPORT The patient had a history of a femoral hernia repair and recurrent lower abdominal pain. Pelvic imaging raised the suspicion of a primary ovarian tumor. The mass appeared to have clear cleavage planes with the surrounding structures, so the patient was proposed for an exploratory laparotomy. Prior to the surgery, an additional pelvic computed tomography (CT) was performed (10 months after the first one), which did not show progression of the disease. The histological examination result was compatible with a benign retroperitoneal schwannoma and not an ovarian tumor. CONCLUSIONS This report highlights that the diagnosis of retroperitoneal and pelvic masses can be challenging. In women, a primary ovarian tumor should be excluded on imaging and the diagnosis of a benign tumor, such as schwannoma, must be confirmed by histopathology, either preoperatively or following tumor resection.

There are less than 150 cases of non-functioning retroperitoneal abdominal schwannoma (NRS) reported. Hormonal assay is crucial in confirming the diagnosis of NRS, as manipulation of a functional retroperitoneal paraganglioma will instigate an abrupt liberation of catecholamines, resulting in devastating consequences. We report the case of 42-year-old woman who presented with headache, night sweats and abdominal discomfort. Cross-sectional imaging demonstrated a retroperitoneal mass adherent to the aorta and inferior vena cava but biochemical testing of blood and urine was negative for metanephrines and normetanephrines. She underwent successful tumour resection via laparotomy, as location increased the complexity and risk of laparoscopic resection., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Although knowledge of the natural history of retroperitoneal schwannoma, including growth rate, would be useful when determining the indications and timing of surgical treatment for such nonpalpable tumors, the existing evidence is unclear. We examined the natural history of retroperitoneal schwannoma and assessed whether magnetic resonance imaging (MRI) and clinical findings predict future growth., Methods: Among patients with retroperitoneal schwannoma treated in our department during the period from January 1, 2015 through December 31, 2015, eight who underwent follow-up assessment by MRI and did not undergo tumor resection for longer than 1 year were enrolled. Changes in lesion size were examined in relation to selected clinical and MRI findings. In cases of pressure erosion in the vertebral body, change in the size of the intraosseous region was compared to change in the size of the whole lesion., Results: Median absolute growth rate (AGR) was 1.9 cm 3 per year, median relative growth rate (RGR) was 5.6% per year, and median tumor volume doubling time (VDT) was 3.1 years. AGR, RGR, and VDT were not associated with any clinical variable. RGR and VDT values in the intraosseous region were about twice those of the whole lesions., Conclusions: The growth rates of retroperitoneal schwannomas varied. Additionally, no MRI or clinical findings predicted growth of retroperitoneal schwannoma. Therefore, careful follow-up is necessary for this tumor type, especially for lesions with bone erosion.

Background: Schwannomas are rare tumours that pose a significant management challenge in the abdomen, retroperitoneum and pelvis. No data are available to inform management strategy., Methods: A collaborative international cohort study, across specialist sarcoma units, was conducted to include adults presenting between 2000 and 2017 with histopathologically confirmed schwannomas within the abdomen, retroperitoneum or pelvis., Results: Of 485 patients across 12 centres, 38 (7·8 per cent) were discharged without follow-up, 199 (41·0 per cent) underwent early resection and 248 (51·1 per cent) had radiological monitoring. Of these 248 patients, 96 (38·7 per cent) eventually had surgery, giving an overall resection rate of 60·8 per cent (295 of 485). At baseline, median tumour volume was 90·1 (i.q.r. 26·5-262·0) cm 3 . The estimated growth rate was 10·5 (95 per cent c.i. 9·4 to 11·6) per cent per year, and was consistent in the short term (within 2 years of diagnosis) and long term (beyond 2 years) (ρ = 0·405, P = 0·021). A decision to operate was more common in symptomatic patients (P < 0·001) and for rapidly growing tumours (growth rate more than 20 per cent per year) (P = 0·025). R0/R1 resection was achieved in 91·6 per cent of patients (263 of 287). Kaplan-Meier long-term recurrence rates after R0/R1 resection were 2·3 and 6·7 per cent at 3 and 5 years respectively., Conclusion: Specific recommendations include: indications for early surgery, prediction of growth from radiological monitoring, promotion of selective submacroscopic resection and cessation of postoperative imaging surveillance., (© 2019 BJS Society Ltd Published by John Wiley & Sons Ltd.)

A characteristics of mediastinal disorders is that the high anatomical density of vital structures in this region represents a challenge for diagnosis and surgical treatment. Space-occupying lesions can grow without causing overt manifestations - or can progress symptom-free - hence they can reach an extreme size by the time of surgery. A 58-year-old male patient was hospitalized for pleural effusion and an extensive, space-occupying mediastinal lesion, which had been causing respiratory symptoms for 15 years. Cytology of the pleural effusion did not confirm malignancy. The CT scan depicted progression manifested as an increase in the size of the lesion with a likely site of origin in the left adrenal gland. According to the MRI, by contrast, the lesion might have originated in the region of vertebrae Th 9-10 , as suggested by the lack of dural continuity. However, its adrenal origin could not be excluded either; endocrine activity was not detected. An operation was performed with a neurosurgeon included in the surgical team. A spinal tumor of the size of 20.2 by 11.1 by 10.8 cm was removed through thoraco-laparotomy, and reconstruction of the diaphragm was performed. Histology confirmed a schwannoma. Postoperatively, the expansion of the lung was only partial, because the patient discontinued respiratory rehabilitation. The follow-up CT scan depicted local recurrence. In the lack of alternative therapeutic modalities, surgical resection is usually the sole option for the management of large, mediastinal space-occupying lesions diagnosed at an advanced stage. Such operations should only be performed in specialist surgical centers and with multidisciplinary collaboration. Orv Hetil. 2019; 160(37): 1476-1479.

The natural history of asymptomatic retroperitoneal schwannomas is poorly understood. This study aimed at investigating the natural history of incidental retroperitoneal schwannomas. The medical charts and imaging studies of 22 asymptomatic patients under observation for at least 12 months for retroperitoneal schwannomas were reviewed. The duration of follow-up ranged between 13 and 176 months (mean 48 months). In the 22 patients managed by the "wait and see" approach, the average tumor size at initial presentation was 51 mm, which increased to 57 mm at final follow-up. During the final follow-up, 2 patients required surgical treatment for tumor enlargement, while the remaining patients remained asymptomatic without surgery. The average growth rate of the tumors was 1.9 mm/year (range: -1.9 to 8.7 mm/year). The majority of asymptomatic retroperitoneal schwannomas demonstrate minimal growth and may be suitable for management with the "wait and see" approach., Competing Interests: The authors have declared that no competing interests exist.

Competing Interests: All authors have disclosed no conflicts of interest.

Background: Traditional approaches for retroperitoneal lumbar plexus schwannomas involve anterior open or laparoscopic resection. For select tumors, the lateral retroperitoneal approach provides a minimally invasive alternative., Objective: To describe a minimally invasive lateral transpsoas approach for the resection of retroperitoneal schwannomas., Methods: A lateral retroperitoneal transpsoas approach was used to resect a 3.1 × 2.7 × 4.1 cm schwannoma embedded within the psoas muscle. A minimally invasive retractor system allows for appropriate visualization and complete resection with the aid of the microscope. The patient tolerated the procedure without complication and was discharged on postoperative day 2 in good condition at her neurological baseline., Results: The lateral retroperitoneal approach provides a minimally invasive alternative for select retroperitoneal schwannomas. In theory, this procedure allows for faster recovery and less blood loss compared to traditional open anterior approaches. For a subset of tumors, anterior laparoscopy may provide better access, but the lateral approach is well known to most neurosurgeons who perform lateral interbody fusions and can be easily tailored to extraforaminal tumor resection., Conclusion: Retroperitoneal schwannomas pose a challenge due to their deep location. The lateral retroperitoneal approach provides a useful alternative for resection of a subset of retroperitoneal schwannomas.

Rationale: Schwannomas are usually benign tumors arising from well-differentiated schwann cells, which rarely occur in the retroperitoneal space. The lack of specific signs and radiologic imaging characteristics makes preoperative diagnosis rather difficult. Most retroperitoneal schwannomas are benign and the primary treatment choice for retroperitoneal schwannomas is surgical excision, however, the involvement of the urinary system is scarcely reported., Patient Concerns: A 34-year-old woman presented with progressive left abdominal pain and rebound abdominal mass at the left lower quadrant for 1 month. Radiological imaging suggested capsulated solid mass with cystic and necrotic areas in the retroperitoneum accompanied by severe left kidney hydronephrosis and preoperative biopsy result was inconclusive., Diagnoses: We believe this is a rare case of retroperitoneal schwannoma complicated with severe hydronephrosis., Interventions: After preparation, the patient underwent laparoscopy exploration and converted to open surgical exploration. The patient accepted complete surgical excision of the retroperitoneal tumor and left kidney. Postoperative pathology diagnosis of the mass was proven to be benign retroperitoneal schwannoma., Outcomes: Postoperative course of the patient was uneventful and the left abdominal pain was greatly improved. After 12-month follow up, no evidence of recurrence or any other complication including renal failure was observed., Lessons: Preoperative imaging and preoperative ultrasound-guided biopsy are helpful to make accurate diagnosis. The final diagnosis is based on postoperative histological and immunohistochemical findings. The primary treatment option is complete surgical resection of the retroperitoneal schwannoma and the involved upper urinary system when severe hydronephrosis occured. Local recurrence and overall survival are closely correlated with negative resection margins and pathology types.

An asymptomatic pelvic tumor was incidentally found in a 27-year-old man. A CT-guided needle biopsy with a pathologic examination confirmed the diagnosis of a benign schwannoma. We describe the complete robotic resection with the conservation of normal fascicles. The postoperative course was uneventful. No neurological deficit occurred, and the electromyogram was normal 6 weeks and 7 months later.

Schwannomas are typically slow growing, encapsulated benign neoplasms. Visceral schwannomas are rare, and preoperative diagnosis is challenging, as they are often confused with other neoplasms even with advanced imaging studies. Surgical excision is usually needed to establish a definitive diagnosis, as pathology is the "gold standard." We review the imaging findings of abdominal schwannomas focusing on pancreatic, gastrointestinal, and retroperitoneal/adrenal schwannomas with pathology correlation. We conclude that schwannoma should be included in the broad differential diagnosis of an abdominal mass and that when it is unnecessary radical resection can be avoided.

Competing Interests: Competing interests: None declared.

We report on a 45-year-old man who presented with pain in the left leg, which he had had for 2 months. A contrast-enhanced CT scan displayed a 25-mm tumor in the lateral side of the left psoas muscle. For this suspected retroperitoneal tumor, we performed laparoscopic resection of the tumor, which was encapsulated by the funicular femoral nerve, using surgical scissors rather than a surgical energy device and preserved the normal fascicles wherever possible. Pathological examination indicated a benign ancient schwannoma arising from the femoral nerve. The patient was able to return to his job 3 weeks after surgery, and he has shown no evidence of recurrence. This was thought to be because of the use of surgical scissors, rather than a surgical energy device, combined with visual magnification. Therefore, the laparoscopic approach is an effective and minimally invasive option for the resection of femoral nerve schwannoma., (© 2016 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and John Wiley & Sons Australia, Ltd.)

Background: Due to variations in location and size, laparoscopic surgery for paraaortic or paracaval neurogenic tumors is challenging. We evaluated the surgical outcomes, as well as surgical tips and tricks., Methods: Between 2000 and 2015, 25 procedures were performed in 24 patients. One patient underwent second surgery due to the recurrence of paraganglioma. Data were collected on the tumor diameter, tumor location, perioperative outcomes, pathology, and last-known disease status. Regarding the operative procedures, we reviewed the operative charts or videos to identify surgical tips and tricks., Results: The median tumor diameter was 5.0 cm (range 1.5-10). The tumor location was suprahilar in 10, hilar in 6, and infrahilar in 9 cases. Regarding the approach, a transperitoneal approach was selected in 24 cases and retroperitoneal approach in 1. The median operative time and blood loss were 208 min (range 73-513) and 10 mL (range 0-1020), respectively. No patient required blood transfusion or conversion to open surgery. Pathological examination revealed paraganglioma in 12, ganglioneuroma in 7, and schwannoma in 6 cases. At the last follow-up, 23 patients were free of disease, while one patient developed metastatic multiple recurrence of paraganglioma 54 months after the second laparoscopic surgery. A review of the surgical records revealed several tips and tricks, including taping the vena cava/renal vein (n = 2) being helpful for detaching a retrocaval tumor from these great vessels, or rotating the kidney to provide a favorable operative view of tumors behind the renal hilum (n = 2). In recent cases, 3D-CT was helpful for preoperative planning., Conclusions: Laparoscopic resection of paraaortic or paracaval neurogenic tumors is feasible in experienced hands. Surgeons should be familiar with detaching maneuvers around great vessels and the mobilization of adjacent organs. Careful preoperative planning is mandatory.

Background: Schwannomas are mesenchymal tumors arising from the neural sheaths of peripheral nerves. They can almost develop in any part of the body, while head, neck and extremities are the most common sites. Occurrence in the retroperitoneum is rare. Schwannomas can show secondary degenerative changes including cyst formation, hyalinization, hemorrhage, and calcification, whereas the ossified retroperitoneal schwannoma was only reported in a malignant one., Case Summary: We first present a benign ossified retroperitoneal schwannoma in a 61-year-old female. The mass was found by a routine health examination. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a well-defined mass in the area among duodenum, right liver, and kidney. Definitive preoperative diagnosis of the mass was difficult. By laparotomy, the mass was found in the retroperitoneum. We completely removed the tumor and gross specimen showed a mass with a capsule and 6 × 6 × 4.8 cm in size. Microscopic examination showed the tumor is composed of spindle-shaped cells with degenerative changes of hemorrhage, calcification, and ossification. Immunohistochemically, S-100 protein was strongly positive. Finally, the mass was diagnosed as a hemorrhagic, calcified, and ossified benign schwannoma in the retroperitoneum. The patient was followed up for a period of 21 months, during which she was well with no evidence of recurrence., Conclusion: We report the first case of a benign retroperitoneal schwannoma with secondary degenerative changes including hemorrhage, calcification, and ossification. Precise preoperative diagnosis of the tumor is challenging even with multiple preoperative imaging modalities. After complete resection, patients with benign retroperitoneal schwanommas generally have good prognosis., Competing Interests: Competing interest: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. The authors report no conflicts of interest.

Objective: To assess the feasibility and safety of a modified retroperitoneoscopic technique in supine position for the primary tumors located below the level of renal pedicle., Materials and Methods: In this retrospective study, 27 patients with primary retroperitoneal tumors located below the level of renal pedicle were recruited from January 2009 till now. The mean age of patients was 49.0 years (36-66 years). The average body mass index was 21.1 ± 1.4 kg/m(2). The retroperitoneoscopic resections were performed in supine position for all patients. The perioperative outcomes were collected and analyzed., Results: All cases were performed by the modified technique without converting to open surgery. The mean operation time was 98.3 ± 12.8 min, with a mean estimated blood loss of 94.4 ± 42.5 mL. There were four patients suffering from intraoperative complications, one with the inferior vena cava (IVC) injury, one with the lumbar vein injury, and other two with the peritoneum breach. Postoperatively, the median bowel recovery time was 2 days (range: 1-3 days), and the mean length of stay after operation was 2.9 ± 1.0 days. Additionally, compared with the tumors located around the aorta (region B), a longer operation time was needed with tumors located around the IVC (region A) (A vs B: 105.8 ± 10.2 vs 91.2 ± 14.4, p = 0.02). Histopathology confirmed paraganglioma in 5 cases, schwannoma in 10 cases, and ganglioneuroma in 12 cases. After follow-up of 12-72 months, no recurrences have been identified., Conclusion: Our modified retroperitoneoscopic technique in supine position was proven to be safe and effective for the treatment of primary retroperitoneal tumors, especially suitable for the tumors located below the level of the renal pedicle.

Introduction: Ancient schwannoma is a rare tumor of the peripheral nerve sheath. As degenerative properties are defined histologically, it can be wrongly interpreted as malignant., Case Presentation: The case presented here is of a giant ancient schwannoma with a pelvic retroperitoneal location, which was mimicking an adnexal mass., Conclusion: In the rarely seen cases in the retroperitoneum, it may reach very large dimensions., Competing Interests: The authors have no conflicts of interest to disclose.

Objective: To investigate the immunohistochemical localization of insulin-like growth factor 1 (IGF-1) and IGF-1 receptor (IGF-1R) in archival specimens of sporadic schwannoma., Method: This study retrospectively analysed the immunolocalization of IGF-1 and IGF-1R in schwannoma specimens collected from all patients with sporadic schwannoma that were treated by two institutions in Japan. The study also evaluated the association between the extent of the IGF-1 and IGF-1R immunoreactivity and several clinicopathological characteristics (age, sex and maximum tumour dimension)., Results: The study examined a total of 29 sporadic schwannoma specimens. IGF-1 and IGF-1R immunoreactivity was detected in the majority of the specimens regardless of their anatomical location. IGF-1 and IGF-1R were not co-localized. There was no association between the extent of the IGF-1 and IGF-1R immunoreactivity and the clinicopathological characteristics of the patients., Conclusions: As IGF-1 and IGF-1R immunoreactivity was detected in the majority of sporadic schwannoma specimens regardless of their anatomical location, these findings suggest that an IGF-1/IGF-1R loop could play a role in the tumorigenesis and progression of schwannomas via an autocrine-paracrine mechanism., (© The Author(s) 2016.)

Schwannomas are primarily benign. Sacral schwannomas in the retroperitoneum are rare and symptoms are uncharacteristic, often hampering diagnosis. Treatment of choice in symptomatic cases is complete excision while observing asymptomatic patients. We present a case of a 68-year-old male with a large intrasacral tumor extending into the pelvis.

Retroperitoneal ancient schwannomas are rare tumors, more usually found in the head, neck and flexor surfaces of the extremities. Ancient schwannomas are a subtype of classic schwannomas with a predominance of degenerative changes, calcifications, hemosiderin deposition, interstitial fibrosis and vascular hyaline degeneration. A 33-year-old male was referred on our hospital with a painful mass in left iliac fossa. The patient underwent surgery and intra-operatively the cystic encapsulated mass was found to be retroperitoneal, between the left psoas major muscle and left iliac muscle. On microscopic examination, we found the presence of Schwann cells in regions with high and low cellularity (Antoni A and B areas) and S100 protein immunohistochemical examination was intensely positive, being consistent with the diagnosis of schwannoma. Complete excision is the only method of the surgical treatment; schwannomas are not sensitive to radiotherapy and chemotherapy. Some authors consider that a complete excision of the tumor, while others believe that enucleated or partial excision of the tumor is sufficient. The prognosis is good, and the most common complication is recurrence, possibly by incomplete excision of it being reported in 5-10% of cases. In conclusion, retroperitoneal schwannomas is usually identified incidentally on tomographic images. Diagnosis is based on histopathological examination after surgery and immunohistochemical examination.

Objective: To explore the clinical characteristics, diagnosis and treatment regimens for retroperitoneal schwannoma., Methods: Clinicopathological data of 53 retroperitoneal schwannoma patients treated from January 1999 to April 2013 in our hospital were collected and analyzed using SPSS 13.0 statistical software., Results: Symptoms of the retroperitoneal schwannoma were vague and nonspecific. 12 patients had interrupted abdominal pain, 9 patients had abdominal discomfort, and only 6 patients presented with abdominal mass while 24 patients were detected by health checkup. There were some characteristics but not specific findings in imaging examination such as CT, ultrasonography and MRI, so preoperative diagnosis rate was low with only 9 patients diagnosed as retroperitoneal schwannoma and 21 patients diagnosed as neurogenic tumor. S-100 immunohistochemisty was very important in pathological diagnosis, and the patients with benign retroperitoneal schwannoma got 100% tumor specific 5-year survival after complete excision while the 5-year survival of malignant retroperitoneal schwannoma was only 50.0%., Conclusions: Retroperitoneal schwannoma is a rare disease. Most of them are benign tumors, and complete surgical excision is the effective treatment.

Various types of neurogenous tumours occur in the retroperitoneum. Hormonally inactive tumours are often asymptomatic and their diagnosis is mostly accidental. Authors are presenting their recent experience with three cases. They discuss diagnostic options and the therapy of retroperitoneal schwannoma, ganglioneuroma and paraganglioma.

Collision tumors within the retroperitoneum are rare. We present the case of a 54-year-old man with an incidental finding of a well-defined iliopsoas mass. He underwent marginal resection via an anterior superior ilio-inguinal approach. Histological examination revealed typical features of a schwannoma surrounded by a notable plasma cell infiltrate. On immunohistochemistry stains, the spindled cells displayed diffuse, strong nuclear and cytoplasmic positivity for S100, whereas epithelial membrane antigen, glial fibrillary acidic protein, and neurofilament stains were uniformly negative. The plasma cell infiltrate was diffusely positive for CD 138, with a majority of them demonstrating positive staining for lambda light chain and negative for kappa light chain. Hematological review found no evidence of marrow plasmacytosis and multiple myeloma was ruled out. At 12 month follow-up, the patient remains free of any recurrence. To our knowledge this is the second case of a schwannoma coexisting with a monoclonal plasma cell infiltrate and the first in the retroperitoneum.

Schwannomas are rare tumors that arise from Schwann cells in neural sheaths. They are commonly found in the central nervous system, spinal cord, or peripheral nerves of the body. Occasionally, they occur in the gastrointestinal tract, with the stomach being the most common site. However, colorectal and retroperitoneal schwannomas are very rare. Preoperative diagnosis is often difficult and definitive treatment entails surgical excision. We herein present 3 cases of intraabdominal schwannomas.

If a testicular cancer patient has a mass in the retroperitoneum, a metastasis is often the first suspicion, probably leading to improper diagnosis and overtreatment. Here we report a case of retroperitoneal schwannoma mimicking metastatic seminoma. A 29-year-old man, who had a history of seminoma, presented with a single retroperitoneal mass suspected to be a metastasis. Because the patient refused radiotherapy, 3 cycles of cisplatin, etoposide, and bleomycin were offered. Post-chemotherapy computed tomography scan revealed persistence of the retroperitoneal mass, with no change in tumor size or characteristics. Subsequently, retroperitoneal lymph node dissection was performed. The dissected tissue contained negative lymph nodes but a single mass in the attached fat. Pathology revealed retroperitoneal schwannoma, which was confirmed by immunohistochemistry. Thus, clinicians should be aware of retroperitoneal schwannoma and its distinction from metastatic seminoma to avoid misdiagnosis and ensure proper treatment.

A 21-year-old woman was admitted to our hospital after incidental detection of a left renal lesion on ultrasound scan. Abdominal contrast-enhanced CT scan revealed a moderately enhanced lesion in the left kidney and a round mass with slight enhancement in the retroperitoneum. FDG PET/CT imaging was performed for whole-body survey, showing increased tracer accumulation in both the left renal and the retroperitoneal lesions. Left renal cell carcinoma with retroperitoneal metastasis was suspected. Synchronous pure epithelioid angiomyolipoma of the left kidney and retroperitoneal schwannoma were diagnosed by pathology. This case highlights that epithelioid angiomyolipoma should be considered as one of the differential diagnosis in renal lesions with increased FDG uptake.

Schwannomas are benign tumors derived from glial cells of peripheral nerve sheaths. They usually occur in association with Von Recklinghausen's disease and most commonly are observed on the head, neck, and upper extremities. Rare morphological variants may be misinterpreted as a malignancy under microscopic examination. The study presented a case of a sporadic "ancient" Schwannoma cell tumor located in the retroperitoneum. Literature data concerning diagnosis and treatment of the above-mentioned pathology was also reviewed.

Retroperitoneal schwannomas are rare and present non-specifically. They usually manifest secondary to their compressive effects on adjacent structures. We describe a patient who presented with recurrent syncope resulting from a large retroperitoneal schwannoma stretching the inferior vena cava and compromising venous return. We also discuss the salient aspects of preoperative investigations leading to definitive diagnosis and surgery., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

Background: Malignant triton tumors are relatively rare and highly aggressive tumors in which malignant schwannoma cells coexist with rhabdomyoblasts. Their occurrence in the retroperitoneum is uncommon and has been rarely reported., Case Presentation: We present the case of a patient with a retroperitoneal malignant triton tumor. A 32-year-old male was referred with epigastric pain and an abdominal mass. Computed tomography revealed a huge soft tissue retroperitoneal mass that involved adjacent organs and vessels. Complete resection was undertaken. Pathological examination confirmed the presence of a malignant triton tumor. The patient died two and a half months after surgery, as a result of local recurrence., Conclusion: Malignant triton tumors are uncommon sarcomas that are associated with a high incidence of developing local recurrence and distant metastases. Immunohistochemical staining showing nerve sheath differentiation with rhabdomyoblastic cells confirms the diagnosis. Complete excision of the tumor is the most effective treatment strategy for these retroperitoneal tumors.

Schwannoma is a benign neoplasm of the Schwann cells of the neural sheath. Most schwannomas occur in the head and neck, and extremities and rarely in the retroperitoneal space. The differentiation of a schwannoma from other malignant tumor or benign tumor is very difficult on a preoperative examination with ultrasonography, computed tomography or magnetic resonance imaging. Furthermore, the lesion with increased fluorodeoxyglucose uptake in PET-CT cannot exclude malignant tumor. Therefore, this lesion needs surgical excision and a histological examination with immunohistochemical staining. We report a case of schwannoma occuring in the retroperitoneal space that incidentally discovered by PET-CT for health-check up. Pathologic confirmation by laparoscopic excision was done.

We present a case of a benign hybrid nerve sheath tumor showing features of both cellular schwannoma and perineurioma.The patient was a 33 year-old female who presented with a 6 month history of pain in the thorax-lumbar region.Axial CT and MIR images showed and homogeneously enhancing solid oval mass involving the left paravertebra region in contact with the vertebral foramina T9-T11. Morphologically the tumor presented a well formed capsule and showed a uniform highly spindle cell proliferation. The spindle cells were arranged in whorls and intersecting fascicles with focal intervening sclerosis and relatively uniform cellularity with a prominent perivascular lymphocytic infiltrate. No cytological atypia, necrosis or mitoses were present. A second cell component was present composed of spindle-shaped cells with inconspicuous bipolar, pale, eosinophilic cytoplasm with oval nuclei. By immunohistochemistry there was a diffuse staining for S-100, and the elongated bipolar cells were EMA, Glut-1 and Claudin-1. To our knowledge this is the first reported case of a hybrid cellular schwannoma/perineurioma.

Schwannomas are rare tumors, usually benign, originating from the nerve sheath, and found only infrequently in the retroperitoneal space. We report on a 67-year-old woman who was initially misdiagnosed and treated for a liver hydatid cyst. After incomplete resection and recurrence of the tumor, we were able to diagnose a large retroperitoneal schwannoma that completely displaced the liver to the left abdomen. The patient underwent surgical resection of the schwannoma; pathological evaluation revealed a cystic tumor measuring 18.5 × 18 × 12.5 cm, with tumor cells staining strongly positive for S-100. Retroperitoneal schwannomas may mimic cystic hepatic tumors and should, therefore, be considered as a differential diagnosis in such cases. We describe the diagnostic modalities and difficulties in the approach of a cystic liver tumor., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Retroperitoneal Schwannomas are uncommonly found in the retroperitoneum and few of them show malignant transformation and invasion. Local recurrence are common in malignant Schwannomas with very few reports of tumor distinct differentiation at recurrences., Case Presentation: We report here a rare case of retroperitoneal schwannoma with multiple origins from retroperitoneum and pelvic wall. Pathological examination confirmed the case as a schwannoma with malignant transformation. Radical dissection of the tumors along with the sacrifice of adjacent sigmoid colon and left kidney failed to provide a cure for this patient. Due to tumor recurrence, a second and a third surgery of radical excision were performed 6 months and 17 months later after the first surgery, respectively. Histopathologic analysis identified that the recurrent tumors were different from the original schwannoma because of their smooth muscle-like differentiation., Conclusion: Malignant schwannomas are uncommon sarcomas with a high incidence of local recurrence. Distinct immunohistochemical staining results of the tumors at recurrence indicate their potential of smooth-muscle like differentiation. Radical excision of the tumors may provide benefit for their local recurrences.

Background: Schwannomas are usually benign tumors that arise from the schwann cells in the neural sheaths of peripheral nerves. Most schwannomas occur in the head, neck, or limbs and rarely in the retroperitoneal space. In the retroperitoneal space, schwannomas are most commonly located near the adrenal gland. We report a successfully resected retroperitoneal benign schwannoma near the inferior vena cava (IVC) using laparoscopic surgery., Methods/results: A 33-year-old woman presented with dull abdominal pain for several months. Magnetic resonance imaging confirmed the existence of a round, sharply demarcated retroperitoneal solid tumor, 42 x 52 mm in size, located between the anterior of the right kidney and the IVC, which was compressed but still patent. The lesion was laparoscopically resected, and pathologic examination revealed a degenerative schwannoma., Conclusion: Laparoscopic surgery is very useful and feasible in the diagnosis and treatment of retroperitoneal schwannoma, with minimal invasiveness and early postoperative recovery., (Copyright 2010 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.)

Background: Schwannomas are uncommon slow growing tumours arising from the nerve sheath or Schwann cell., Objective: To report a case and the surgical removal of a giant complex schwannoma and to highlight the value of extensive investigations including a preoperative histologic diagnosis in the successful surgical management of uncommon large benign tumours., Methods: A 39-year-old man presented with a 15-year history of a large mass in the right gluteal region. He was clinically evaluated, subjected to imaging studies and surgery., Results: Clinical examination revealed a 40 cm by 60 cm mass in the right gluteal region and continuous with a 25 cm by 15 cm pelvic mass. The ultrasound scan revealed a very complex (mixed solid and fluid containing) gluteal mass with extension to the pelvis. The CT scan showed a very large, well defined lobulated tumour with cystic spaces and enhancing nodules. The tumour extended through the ischiadic foramen into the pelvis and posteriorly into the thigh muscles. A Doppler scan of the pelvic vessels revealed that the right common and internal iliac arteries were both compressed but not occluded. An incisional biopsy was reported as a Schwannoma with xanthomatous changes and an immuno histochemistry profile of S-100+, Ki-67+ (less than 1% of the cells). A right foot drop following the surgery responded to physiotherapy. The duration of total hospital stay was 12 weeks., Conclusion: The staged excision of large and complex schwannomas is safe. It is essential that a preoperative histological diagnosis is made to establish that the tumor is truly benign.

Ancient schwannomas are rare tumors of neural origin. We present a case of a retroperitoneal ancient schwannoma by discussing the main symptoms, ultrasound and CT findings, treatment, and histopathological characteristics.

Retroperitoneal schwannomas are rare tumours originating from Schwann cells of peripheral nerve sheaths. Their clinical presentation is often delayed as they grow to a large size in a non-restrictive space, such as the retroperitoneum, before any clear symptomatology is manifested. Furthermore, the symptoms may mimic different diseases and be aspecific. The preoperative diagnosis is often unclear as no pathognomonic radiological features are known. Fine needle biopsy is not diagnostic due to tumour cell pleomorphism. We report the case of a 51-year-old woman presenting with unusual symptoms such as severe constipation, bowel distension, excess flatus, postprandial fullness and abdominal pain due to left colon compression by a large retroperitoneal tumour. A complete resection of the mass combined with sparing of the surrounding tissues was carried out through a midline laparotomy. Microscopic evaluation and immunohistochemistry documented a benign retroperitoneal schwannoma. Postoperatively, complete resolution of abdominal symptoms and no major complications were observed. At 28 months' follow-up no local recurrence was found. To the best of our knowledge, this is a rare case of retroperitoneal schwannoma with definite abdominal symptoms and with sudden onset of severe constipation.