Malignant triton tumor of the gluteal region in a patient unaffected by neurofibromatosis: A case report

Malignant triton tumor (MTT) is a rare variant of malignant peripheral nerve sheath tumor (MPNST) made up of both malignant schwannoma cells and malignant rhabdomyoblasts.A 26-years-old male patient was admitted with an asymptomatic gluteal mass. Magnetic resonance imaging showed heterogeneous soft tissue mass and he underwent open biopsy. Malignant peripheral nerve sheath tumor was diagnosed. He was given adjuvant chemotherapy following the removal of the tumor with hip disarticulation. The tumor was diagnosed as “malignant triton tumor” based on pathological examination including immunohistochemical studies. There were no signs of metastasis but recurrence was observed at 9 months follow up.MTT is usually associated with Neurofibromatosis 1 and located in head, neck region. In this case sporadic involvement of gluteal region and aggressive behavior of the lesion despite radical surgery was demonstrated.     

A case of metastatic intracerebral malignant schwannoma]

A 53 year old male complaining of headache and left hemiparesis was referred to our hospital on November 11, '89. He had no evidence of von Recklinghausen's disease. He had been operated on because of a well circumscribed tumor in the left paravertebral muscle on July 11, '87, and metastasis in the lower lobe of the left lung on April 20, '88. The pathological diagnosis of both the primary and the metastatic lung tumor was malignant peripheral nerve sheath tumor showing peripheral cell differentiation (malignant schwannoma). Contrast enhanced CT demonstrated an irregularly enhanced mass in the right parietal lobe just before admission. On the night of admission November 12, '89, he suddenly had severe headache and this progressed to hemiparesis. Repeat CT examination was done immediately and revealed intratumoral hemorrhage. On November 19, '89, the tumor was totally removed. His symptoms disappeared postoperatively. The pathological findings of the tumor were the same as those made previously. The patient received radiotherapy to the brain (local 50 Gy and whole brain 30 Gy) and chemotherapy with nitrosourea (MCNU 150mg). He was discharged without neurological deficits. However he had two operations to remove metastatic tumors in the soft tissue of the hip on January 12, and August 17, '90. A very rare case of metastatic intracerebral malignant schwannoma is reported, and the literature on this point is reviewed.     

A case report of retroperitoneal malignant schwannoma

A case of retroperitoneal malignant schwannoma is reported. The patient was a 66-years-old man who was referred to our clinic because of an abdominal lump. CT scan and renal arteriography pointed out right renal cyst, but the tumor was separate from the right kidney at operation. Pathological diagnosis of this retroperitoneal tumor was malignant schwannoma. After 10 months he developed local recurrence and had transabdominal excision. He has been doing well 12 months after the second operation. Thirty-one cases of retroperitoneal malignant schwannoma in Japan are reviewed.     

Malignant peripheral nerve sheath tumor mimicking carotid body tumor--case report and review

Malignant peripheral nerve sheath tumor is a rare neurogenic tumor that usually presents in geriatic patients. Typically, it is found in the trunk and extremities and rarely presents in the head and neck region. It may mimic a carotid body tumor when it presents in the neck. We report the first case of malignant peripheral nerve sheath tumor of the vagus nerve in an adolescent boy. He presented with an asymptomatic lateral neck lump that was thought to be a benign schwannoma on preoperative imaging. We describe the diagnostic dilemma and management difficulties in this patient and review the literature.     

Intraosseous schwannoma of thoracic 12 vertebra without spinal canal involvement

Schwannomas are of common tumors of the nerve sheath cells. They present as well-circumscribed masses attached to the peripheral nerves, cranial nerves, or spinal nerve roots. Intraosseous localization of these tumors is rare. The presented case is a 55-year-old female patient, the very first case of intraosseous schwannoma of Th12 vertebra without spinal canal involvement. She was admitted with a progressive back pain and seldom pain and numbness in the right leg for 1 year. Preoperative findings on computed tomography and magnetic resonance images of the lesion resembled that of any primary tumor of the bone. The patient was operated on via posterior approach and the tumor was removed totally. Histopathological examinations revealed schwannoma. Our case emphasizes the heterogeneous presentation of the nerve sheath cell tumors in the differential diagnosis of the primary vertebral column tumors.     

Angiosarcoma arised from a solitary schwannoma of the chest wall

Angiosarcomas rarely develop within a peripheral nerve or a peripheral nerve sheath tumor. A 68-year-old woman was admitted for right hemothorax. She had suffered from the left thoracic empyema and the right chest wall tumor which had been regarded as schwannoma clinically. Anemia got serious due to continuous bloody effusion. Although bleeding point was not detected by thoracotomy. The right chest wall tumor was resected. Postoperatively bloody effusion still drained continuously, she died ten days after the operation. Resected tumor was almost necrotized. The tumor was diagnosed as angiosarcoma pathologically, in which a part of schwannoma component resided. It is indicated that angiosarcoma in this case arised from degenerated schwannoma. It is necessary to consider angiosarcoma, rarely arised from degenerated schwannoma, during conservative, long-term observation on the care of schwannoma.     

手部神经肿瘤的诊治

目的探讨手部神经肿瘤的诊治。方法1998年1月至2003年12月，对诊治的6例手部神经肿瘤采用手术切除。1例术前误诊为腱鞘炎、腱鞘结核，术后病理诊断为正中神经脂肪纤维瘤。1例术中误将尺神经浅支与肿瘤一同切除，行神经修复术，术后诊断为神经鞘瘤。3例手背、1例指背感觉支神经纤维瘤。结果6例随访8个月～2年，除1例环指尺侧、小指感觉稍减退外，余几例感觉、运动功能均正常，肿瘤无复发。结论手部浅表肿瘤的症状与体征较相似，容易误诊、误治；对手部神经肿瘤采用手术切除是主要的治疗方法。     

Laparoscopic extraperitoneal excision of a nerve sheath tumor of the spermatic cord

A 60-year-old male presented with a nontender irreducible mass in the right groin. Examination revealed swelling in the inguinal canal in the region of the deep inguinal ring. He underwent laparoscopic, extraperitoneal exploration of the spermatic cord, where a soft tissue tumor was identified and excised. Histological examination confirmed a nerve sheath tumor. Nerve sheath tumors are uncommon neoplasms of peripheral nerves, which theoretically can arise from any nerve fiber but have only been described in the spermatic cord in three reports in the literature. We are not aware of any reports describing their excision either laparoscopically or by the extraperitoneal route.     

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,preopera- tive clinical diagnosis is difficult.Therefore,this disease should be listed as differential diagnosis for liver tumor with clinically benign characteristics.     

Multiple schwannomas of the bilateral mediastinal vagus nerves

Multiple schwannomas arising from the mediastinal vagus nerve are very rare, but herein we report a case with such lesions involving the bilateral intrathoracic vagus nerves. A 43-year-old man presented with multiple mediastinal tumors during a check-up. A chest computed tomographic scan revealed multiple lesions that appeared strung together like beads along the right vagus nerve. Three small tumors were also evident on the left side of the esophagus. We performed a complete resection of the bilateral mediastinal tumors through right thoracoscopic surgery. The pathologic diagnosis for each of these tumors was a schwannoma without malignant components.     

Cerebral metastasis from an epithelioid malignant schwannoma: case report.

The authors present a case of brain metastasis from an epithelioid malignant schwannoma. The patient previously had undergone a surgical resection of the primary tumor in the right forearm. The neoplasm was composed of nests of cells with an entirely epithelioid appearance without spindle cell areas. Immunohistochemically, the tumor cells stained positive for S100 protein and negative for cytokeratin, neuron-specific enolase, and anti-melanoma antiserum. To our knowledge, this is the first reported case of cerebral metastasis from an epithelioid malignant tumor of the peripheral nerve sheath.     

Tentorial schwannoma in a 64-year-old female: case report

A 64-year-old woman presented with the history of transient global amnesia. Magnetic resonance imaging with contrast medium showed a lobulated heterogeneously enhanced cystic lesion attached to the superior surface of the right tentorium, indenting the right temporal lobe laterally and midbrain medially. A small part of the lesion was located under the right tentorium and did not involve the right trigeminal nerve. The lesion was subtotally resected via the subtemporal approach and did not affect the trochlear and trigeminal nerves. Histological examination showed that the lesion was schwannoma. Intracranial schwannomas usually arise from the cranial nerves. The present case of tentorial schwannoma not associated with the cranial nerves is extremely rare. Schwannoma should be included in the differential diagnosis of tumors arising from the tentorium.     

Malignant schwannoma of acoustic nerve: a case report

During a routine physical examination in 1976, a 54-year-old man was noted to suffer from hearing difficulty and continuing tinnitus of his right ear. He had, however, no further consultations for the next five years, although the symptom persisted and gradually worsened. In May 1981, he experienced complete hearing loss in his right ear. A computed tomography disclosed no abnormalities, and other laboratory tests were unremarkable. In September 1981, the patient began to complain of paresthesia of the right angle of the mouth and tongue, right-sided facial paralysis, and walking difficulty. A repeated computed tomography showed a tumor at the right cerebellopontine angle region. A clinical diagnosis of acoustic schwannoma was made. The first operation was performed in December 1981. Complete removal of the tumor was impossible because of its unexpected, unusual hardness. The pathologic diagnosis was a malignant mesenchymal tumor, compatible with a malignant nerve sheath tumor of the acoustic nerve. A second operation was performed in January 1982, but the rapid postoperative regrowth of the tumor necessitated a third operation in March 1982. The patient died in the next month. Family histories did not show any evidence of von Recklinghausen's disease, and neither did the patient have any clinical stigmata of this disease.     

Peripheral Nerve Schwannoma: A Review of Varying Clinical Presentations and Imaging Findings

A schwannoma or neurilemmoma is a benign, isolated, noninvasive, and encapsulated tumor originating from Schwann cells of the peripheral nerve sheath. The incidence of a schwannoma occurring in the foot and ankle is rare, with prevalence rate of 1% to 10%. Schwannomas have no sex predilection, and they commonly occur in patients in their fourth decade. Malignant transformation of benign schwannoma is unusual; however, it is important to note that malignant variants of schwannomas do exist and account for about 5% to 10% of all soft tissue sarcomas. We present 3 cases of benign schwannoma in the lower extremity. All 3 patients presented with varying clinical symptoms, including pain, paresthesia, weakness, and a palpable mass. A schwannoma was eventually diagnosed in all 3 patients. We discuss and review the known entities of peripheral nerve schwannoma and describe the clinical and imaging findings and therapeutic strategies for treating and diagnosing peripheral nerve schwannoma.     

Malignant schwannoma of the sciatic nerve originating in a spinal plexiform neurofibroma associated with neurofibromatosis type 1--case report.

A 26-year-old man with neurofibromatosis type 1 (NF1) presented with a giant malignant schwannoma of the sciatic nerve. The differential diagnosis of malignant peripheral nerve sheath tumor (MPNST) was based on clinical, radiological, and histological evidence. The tumor apparently originated in a spinal plexiform neurofibroma. The lesion was resected totally without neural damage to the sciatic nerve. However, the tumor recurred within 2 months. The patient died of unknown factors probably associated with the spinal involvement. MPNST associated with NF1 has a poor prognosis due to recurrence or metastasis despite complete macroscopic removal.     

Malignant Vestibular Schwannoma

A 61-year-old woman underwent a translabyrinthine resection of a right intracanulicular acoustic neuroma, which had been detected in the work-up of sudden hearing loss. At the time of surgery, the tumor was roughly twice as large as indicated by the magnetic resonance scan taken only 2 months previously. The tumor eroded the vertical and transverse crests and extended well into the cerebellopontine angle. It was impossible to distinguish the facial nerve proximal to the geniculate ganglion. All visible tumor was resected, along with the facial nerve. Histological evaluation showed a highly cellular tumor, with many mitoses and areas of necrosis, meeting the criteria for malignant schwannoma. The patient has no stigmata of neurofibromatosis, and has no known relatives with that condition. This case is only the fourth reported of a malignant vestibular schwannoma. The relationships between vestibular schwannoma, neurofibromatosis, and malignancy are discussed.     

Malignant vestibular schwannoma

A 61-year-old woman underwent a translabyrinthine resection of a right intracanulicular acoustic neuroma, which had been detected in the work-up of sudden hearing loss. At the time of surgery, the tumor was roughly twice as large as indicated by the magnetic resonance scan taken only 2 months previously. The tumor eroded the vertical and transverse crests and extended well into the cerebellopontine angle. It was impossible to distinguish the facial nerve proximal to the geniculate ganglion. All visible tumor was resected, along with the facial nerve. Histological evaluation showed a highly cellular tumor, with many mitoses and areas of necrosis, meeting the criteria for malignant schwannoma. The patient has no stigmata of neurofibromatosis, and has no known relatives with that condition. This case is only the fourth reported of a malignant vestibular schwannoma. The relationships between vestibular schwannoma, neurofibromatosis, and malignancy are discussed.     

A case of schwannoma of intrathoracic right phrenic nerve

A 22-year old man was admitted because of an abnormal shadow on his chest X-ray film. Radiographic findings revealed that the tumor was located in the right middle mediastinum. At operation a smooth round tumor was found arising from the right phrenic nerve. The tumor was removed with phrenic nerve. Pathohistological examination revealed this tumor was benign schwannoma. Intrathoracic schwannoma usually arise from intercostal and sympathetic nerve and that arising from phrenic nerve is very rare. We removed the tumor by means of cutting his right phrenic nerve because of complete resection. Postoperatively he did well without any respiratory distress. And his respiratory function studies recovered normal 9 months after the operation. We think that schwannoma arising from phrenic nerve should be removed completely and in such a case cutting of the one side phrenic nerve is at ease if the patient have normal respiratory function.     

Bifocal schwannoma of the sciatic nerve: a case report

Schwannoma is a benign tumor generally observed on peripheral nerves. A sciatic localization is rare, observed in 1% of the patients. Multiple localizations have been reported in exceptional cases. We report the case of a bifocal schwannoma observed at the bifurcation of the sciatic nerve in a high-level athlete. The misleading clinical presentation of this localization causes a delay in diagnosis.     

Schwannoma with rhabdomyoblastic differentiation: a unique variant of malignant triton tumor

A 54-year-old woman presented with intractable perianal, bilateral buttock, and radiating thigh/calf pain. An MRI scan showed an intradural, contrast-enhancing, ovoid mass in the cauda equina region at L1-L2. At laminectomy, the ovoid mass arose from a nerve root and, intact, was gross totally resected. Histologically, the dominant pattern was that of schwannoma. One year thereafter, the symptoms recurred. An MRI scan demonstrated an irregular, heterogeneously enhancing tumor recurrence. A repeat laminectomy disclosed a large fleshy tumor involving multiple nerve roots. The lesion was subtotally resected and showed pluridirectional differentiation toward embryonal rhabdomyosarcoma, primitive neuroectodermal tumor, and rare malignant epithelial cells. Review of the original tumor disclosed only foci of embryonal rhabdomyosarcoma and primitive neuroectodermal tumor. Based upon available data regarding divergent differentiation in peripheral nerve sheath tumors, this is a unique, previously undescribed tumor demonstrating rhabdomyosarcomatous, primitive neuroectodermal tumor and scant epithelial differentiation in a schwannoma. In essence, it is a variant of malignant Triton tumor because of its origin in a tumor consisting of well-differentiated Schwann cells. It supports the contention that the Schwann cell is the source of a variety of heterologous elements in nerve sheath tumors.