[Rare case of retroperitoneal malignant Schwannoma]

Malignant Schwannoma, recently renamed malignant peripheral nerve sheat tumor retroperitoneally localized, represents 0.01 of retroperitoneal tumours. A 41-year old woman, without pathological record--and without cutaneous neurofibromatosis--hospitalized for increased volume of the abdomen, without symptomatology, is diagnosed after the imaging and biological tests--without CT and RMN--with retroperitoneal tumour. The unusual size of tumour--6000 gr.--the macroscopic aspect suggesting malignancy (histopathologically and immunohistochemically confirmed), the relatively easy extirpation which, nevertheless, required caudal spleen- and pancreatectomy as well as transvers colectomy, the absence of proximity adenopathy and remote secondary determinations, the simple postoperative evolution represent overwhelming elements in this case. Two years after the operation, during which the patient was under chemotherapy, on a routine control we found a relapse at a distance from the initial tumour (primitive tumour ?), totally operable. For the time being, after almost five years from the first operation, there are no clinical, biological and imaging changes.

CONCLUSIONS

the retroperitoneal space is quite enough for the development of large tumour masses, without symptomatology. The present case combines most characteristics of retroperitoneal neoplasms: large or very large size, quasi-absent symptomatology, difficulty in preoperative diagnosis, surgical tactics and techniques--quite often, the total extirpation of tumour mass led to the sacrifice of other organs within the limits of a justified risk--and unforeseeable evolution with relapses having the same characteristics.

Radiation-induced femoral arteritis

Radiation arteritis is currently an uncommon sequalae of external beam radiation, however because of the increasing use of radiotherapy in the management of neoplastic conditions its recognition is increasingly important. We present two cases of debilitating femoral occlusive disease, secondary to radiation exposure, at a long period post irradiation and review the pathophysiolgy and management options for this condition.

Intracranial subfrontal schwannoma treated with surgery and 3D conformal radiotherapy

Subfrontal schwannoma not arising from the cranial nerves are rare tumors. A 19-year-old man presented with a large subfrontal extra-axial enhancing mass with a preoperative diagnosis of skull base meningioma. A subtotal resection of the tumor mass was carried out. Microscopic examination revealed it to be a schwannoma. The residual tumor was treated with fractionated three-dimensional conformal radiotherapy (3D CRT). The rationale of treating with radiotherapy in such cases is analyzed.

Malignant Nerve Sheath Tumor of the Right Cerebral Peduncle: Case Report

OBJECTIVE AND IMPORTANCE

Schwannomas occurring in the neuraxis are very rare. Usually, these tumors are benign. Primary malignant intracerebral nerve sheath tumors are extremely rare, with only five documented cases in the international literature. We report one case of a primary malignant intracerebral nerve sheath tumor occurring in the right cerebral peduncle of a 35-year-old man.

CLINICAL PRESENTATION

Magnetic resonance imaging revealed a heterogeneous peripherally enhancing mass of the right cerebral peduncle, surrounded by a small edema.

INTERVENTION

Unlike the five cases previously reported, this is the first time a stereotactic biopsy has been performed, and this is the only patient who responded to cranial radiation therapy for approximately 2 years. When the tumor recurred, a systemic chemotherapy treatment was prescribed. No positive response was seen, and the patient died 29 months after the initial diagnosis.

CONCLUSION

An accurate diagnosis and planned aggressive treatment seem to be the key elements in the management of the disease.

Intra-cerebral schwannoma simulating glioma

An intra-cerebral schwannoma, presenting as a cystic, calcified, enhancing frontal mass, arising in a 52-year-old woman was misdiagnosed as a glioma and treated with radiotherapy. This observation emphasizes the importance of careful histological reexamination of all brain tumors when a discrepancy appears between the initial histological diagnosis and the clinical evolution, in order to recognize rare curable entities and to avoid potentially toxic treatment.

Superficial malignant schwannoma of the scalp

BACKGROUND

Malignant schwannoma is a rare sarcoma that is located mostly on trunk and extremities; the head and neck are unusual sites for its development. Almost half of these tumors arise from neurofibromas with or without von Recklinghousen's disease, and most of the remainder develop de novo from peripheral nerve trunks. Development in the superficial soft tissues is extremely rare.

OBJECTIVE

To present a case of superficial malignant schwannoma of the scalp, which is an uncommon presentation.

METHODS

An 80-year-old male patient presented with a painless ulceration on his scalp. The clinical and radiologic properties of the tumor were consistent with a skin tumor.

RESULTS

The lesion was excised, and reconstruction was achieved by transposition scalp flap. Malignant schwannoma was given as diagnosis by histopathologic examination with immunohistochemistry.

CONCLUSION

Malignant schwannomas may also occur in the skin. Clinically, these superficial forms closely resemble skin tumors, especially malignant melanoma. The treatment of choice in these tumors is wide resection combined with radiotherapy.

Feasibility of insertion/implantation of 2.0-mm-diameter gold internal fiducial markers for precise setup and real-time tumor tracking in radiotherapy

PURPOSE

To examine the feasibility and reliability of insertion of internal fiducial markers into various organs for precise setup and real-time tumor tracking in radiotherapy (RT).

MATERIALS AND METHODS

Equipment and techniques for the insertion of 2.0-mm-diameter gold markers into or near the tumor were developed for spinal/paraspinal lesions, prostate tumors, and liver and lung tumors. Three markers were used to adjust the center of the mass of the target volume to the planned position in spinal/paraspinal lesions and prostate tumors (the three-marker method). The feasibility of the marker insertion and the stability of the position of markers were tested using stopping rules in the clinical protocol (i.e., the procedure was abandoned if 2 of 3 or 3 of 6 patients experienced marker dropping or migration). After the evaluation of the feasibility, the stability of the marker positions was monitored in those patients who entered the dose-escalation study.

RESULTS

Each of the following was shown to be feasible: bronchoscopic insertion for the peripheral lung; image-guided transcutaneous insertion for the liver; cystoscopic and image-guided percutaneous insertion for the prostate; and surgical implantation for spinal/paraspinal lesions. Transcutaneous insertion of markers for spinal/paraspinal lesions and bronchoscopic insertion for central lung lesions were abandoned. Overall, marker implantation was successful and was used for real-time tumor tracking in RT in 90 (90%) of 100 lesions. No serious complications related to the marker insertion were noted for any of the 100 lesions. Using three markers surgically implanted into the vertebral bone, the mean +/- standard deviation in distance among the three markers was within 0.2 +/- 0.6 mm (range -1.4 to 0.8) through the treatment period of 30 days. The distance between the three markers gradually decreased during RT in five of six prostate cancers, consistent with a mean rate of volume regression of 9.3% (range 0.015-13%) in 10 days.

CONCLUSIONS

Internal 2.0-mm-diameter gold markers can be safely inserted into various organs for real-time tumor tracking in RT using the prescribed equipment and techniques. The three-marker method has been shown to be a useful technique for precise setup for spinal/paraspinal lesions and prostate tumors.

Calculation of rotational setup error using the real-time tracking radiation therapy (RTRT) system and its application to the treatment of spinal schwannoma

PURPOSE

The efficacy of a prototypic fluoroscopic real-time tracking radiation therapy (RTRT) system using three gold markers (2 mm in diameter) for estimating translational error, rotational setup error, and the dose to normal structures was tested in 5 patients with spinal schwannoma and a phantom.

METHODS AND MATERIALS

Translational error was calculated by comparing the actual position of the marker closest to the tumor to its planned position, and the rotational setup error was calculated using the three markers around the target. Theoretically, the actual coordinates can be adjusted to the planning coordinates by sequential rotation of gamma degrees around the z axis, beta degrees around the y axis, and alpha degrees around the x axis, in this order. We measured the accuracy of the rotational calculation using a phantom. Five patients with spinal schwannoma located at a minimum of 1-5 mm from the spinal cord were treated with RTRT. Three markers were inserted percutaneously into the paravertebral deep muscle in 3 patients and surgically into two consecutive vertebral bones in two other patients.

RESULTS

In the phantom study, the discrepancies between the actual and calculated rotational error were -0.1 +/- 0.5 degrees. The random error of rotation was 5.9, 4.6, and 3.1 degrees for alpha, beta, and gamma, respectively. The systematic error was 7.1, 6.6, and 3.0 degrees for alpha, beta, and gamma, respectively. The mean rotational setup error (0.2 +/- 2.2, -1.3 +/- 2.9, and -1.3 +/- 1.7 degrees for alpha, beta, and gamma, respectively) in 2 patients for whom surgical marker implantation was used was significantly smaller than that in 3 patients for whom percutaneous insertion was used (6.0 +/- 8.2, 2.7 +/- 5.9, and -2.1 +/- 4.6 degrees for alpha, beta, and gamma). Random translational setup error was significantly reduced by the RTRT setup (p < 0.0001). Systematic setup error was significantly reduced by the RTRT setup only in patients who received surgical implantation of the marker (p < 0.0001). The maximum dose to the spinal cord was estimated to be 40.6-50.3 Gy after consideration of the rotational setup error, vs. a planned maximum dose of 22.4-51.6 Gy.

CONCLUSION

The RTRT system employing three internal fiducial markers is useful to reduce translational setup error and to estimate the dose to the normal structures in consideration of the rotational setup error. Surgical implantation of the marker to the vertebral bone was shown to be sufficiently rigid for the calculation of the rotational setup error. Fractionated radiotherapy for spinal schwannoma using the RTRT system may well be an alternative or supplement to surgical treatment.

[Paralateral-nasal malignant schwannoma with rhabdomyoblastic differentiation (Triton tumor). Report of a case]

Malignant schwannoma with rhabdomyoblastic differentiation (Triton tumor) is a very rare variant of the malignant tumors arising in the peripheral nerve sheath. In 70% of the cases, the neoplasm is associated with Von Recklinghausen's neurofibromatosis; in the remaining 30% it is the sole morbid finding. Its biological behaviour is, in any case, more aggressive than that of simple malignant schwannoma; its course is rapid and its prognosis is dismal. Local recurrences are frequent, and distant metastases, preferentially situated in the lung and brain, are present in about 50% of the cases. Post-operative radiotherapy is always indicated. We report a case of a 64-year-old man who presented a right paralatero-nasal Triton tumor. Following exeresis, a cycle of high-dose radiotherapy was prescribed; the 10-year follow-up revealed no sign of recurrence or distant metastases.

Management of benign cranial nonacoustic schwannomas by fractionated stereotactic radiotherapy

Schwannomas are the most common tumors of cranial nerves. Nonacoustic schwannomas are very rare tumors, accounting for approximately 10% of intracranial schwannomas. Standard treatment is complete surgical resection if possible. The role of fractionated stereotactic radiotherapy remains to be defined. Thirteen patients with cranial nonacoustic schwannomas underwent fractionated stereotactic radiotherapy. Seven patients had trigeminal schwannomas, three schwannomas of the lower cranial nerves, and three located in the cerebellopontine angle without involvement of the acoustic nerve. Treatment included primary or adjuvant radiotherapy in progressive disease. Tumor volume ranged from 4.5 to 76.0 cc (median 19.8 cc). Median dose was 57.6 Gy with 1.8 Gy/fraction. Median follow-up was 33 months (range 13-70 months). Local tumor control rate was 100% (13/13). Tumor size remained stable in nine patients and decreased in four. Improvement of preexisting neurological deficits was seen in four cases. No patient developed new cranial nerve or brain stem deficits. No patient showed clinically significant complications of irradiation. Fractionated stereotactic radiotherapy is an effective and well-tolerated noninvasive treatment for cranial nonacoustic schwannomas with excellent tumor control rates. It is an option for patients at higher risk for microsurgical resection or in residual and recurrent tumors.

Radiotherapy and radiosurgery for skull base tumors

Tumors arising in the vicinity of the skull base are relatively uncommon; however, lesions that may be successfully treated by radiotherapy and radiosurgery include temporal bone chemodectomas, schwannomas, juvenile angiofibromas, pituitary adenomas, and meningiomas. This article reviews treatment techniques and results and discusses the pertinent literature.

Primary pigmented malignant schwannoma in the posterior mediastinum

This paper describes a rare case of primary pigmented malignant schwannoma arising from the sympathetic trunk in the posterior mediastinum. A 30-year-old woman underwent a thoracoscopic tumor extirpation. A primary pigmented malignant schwannoma was diagnosed histologically. The tumor presented fascicles and whorls of pigmented plump spindle cells and positive immunoreactivity to S-100 protein, vimentin, and HMB-45. Postoperative radiotherapy of the mediastinum was performed. Our case demonstrates the successful thoracoscopic resection and postoperative radiation treatment of a malignant schwannoma.

Correlation of intraoperatively irradiated volume and fibrosis in patients with soft-tissue sarcoma of the extremities

PURPOSE

To investigate the influence of intraoperatively irradiated volume on soft-tissue fibrosis.

METHODS AND MATERIALS

Fifty-three patients with soft-tissue sarcoma of the extremities were treated with intraoperative radiotherapy (IORT) (median dose 15 Gy) and postoperative fractionated therapy (median dose 46 Gy). The median follow-up was 41.5 months (range 18-94). Late toxicity was classified according to the LENT-SOMA criteria. A Cox regression model was calculated to identify the parameters that could influence soft-tissue fibrosis Grade 3 or 4. Five parameters were observed: extent of surgical procedure, IORT in case of recurrence, extent of IORT volume, extent of IORT dose, and extent of postoperative volume. In addition, a logistic regression model was calculated to demonstrate the relationship between the IORT volume and fibrosis development.

RESULTS

The overall survival rate after 5 years was 84%. The actuarial tumor control rate was 90% after 5 years. Eleven patients developed soft-tissue fibrosis. Five patients developed Grade 3 fibrosis and 1 patient developed Grade 4 fibrosis. Only the IORT volume had a significant influence on Grade 3 or 4 fibrosis development. An IORT volume of 210 cm(3) conveyed a 5% risk (confidence interval 1-20%) of the development of severe fibrosis. The risk of severe Grade 3 or 4 fibrosis increased to 50% (confidence interval 15-80%) if a volume of 420 cm(3) was irradiated.

CONCLUSION

The effect of volume in patients treated with IORT was remarkable. The ratio of side effects was relatively low. The risk of soft-tissue Grade 3 or 4 fibrosis increased with the extent of the IORT volume. Compared with the literature, IORT provides excellent local control in these patients.

Patient position reproducibility in fractionated stereotactically guided conformal radiotherapy using the BrainLab mask system

PURPOSE

Dedicated mask systems nowadays allow the use of stereotactic radiotherapy in fractionated regimes, therefore combining the advantages of high precision radiotherapy with the biological benefit of fractionation. Therefore the knowledge of institution specific isocenter accuracy is essential for decision-making about margins to be allowed to form the planning target volume.

PATIENTS AND METHOD

Measurements of isocenter deviations during fractionated treatments were performed in 33 patients using the simulator Simulix-xy (Oldelft) in connection with the BrainLab angiographic localizer-box as well as port-films. In both cases repeated images were overlaid by use of anatomical landmarks with a methodical accuracy in the order of 0.5 mm.

RESULTS

Both methods yield random isocenter deviations of less then 2 mm (standard deviation) in all three directions and no significant systematic deviations. These values are in the order of the accuracy of the method, obtained by comparison of two independent investigators, as well as they are comparable with the literature.

CONCLUSIONS

The accuracy of less than 2 mm indicates safety margins of 3-4 mm as sufficient for clinical routine to cover the target in 95.5% of all set-ups (2 SD).

Malignant schwannoma of the trigeminal nerve

SUMMARY

We present the MR imaging, CT, and clinical findings of a patient with malignant schwannoma of the trigeminal nerve. Local tumor recurrence is frequent and may be mistaken for lymphatic spread. In this report, we emphasize the natural history of this rare tumor and discuss the importance of imaging in diagnosis and surveillance.

[Malignant schwannoma of parotid gland. Case report and review of literature]

The authors described a rare malignant neoplasm of peripheral nerve sheath, sarcomatous neurillemoma, localized in parotid gland in 72-year female. Findings of the computer tomography, nuclear magnetic resonance and Doppler-ultrasound are presented and discussed. A review of world literature, including 14 cases of this tumor, was made.

[Fractionated radiotherapy of intracranial meningiomas and neurinomas]

In most institutions, surgical excision remains the standard treatment of meningiomas and neurinomas; the aim of surgery is complete resection. However, total removal is not always feasible without significant morbidity and in some cases, the patient's condition contraindicates surgery. For incompletely excised tumors, recurrences will have consequences on neurological functions. There are now many reports in the literature confirming the fact that radiotherapy significantly decreases the incidence of recurrence of incompletely resected benign tumors and that it can replace surgery in some situations where an operation would involve considerable danger or permanent neurological damage: about 80 to 90% of such tumors are controlled with fractionated radiotherapy. Stereotaxic and three-dimensional treatment planning techniques increase local control and central nervous system tolerance so that the respective place of surgery and radiotherapy needs to be redefined, considering efficacy and morbidity of these two therapeutic means. In this article, we limit our remarks to fractionated radiotherapy and, after a review of the literature, we discuss the indications, volume evaluations and the techniques currently used.

[Sarcomas of the vulva. Report of 2 cases]

We report two cases of vulvar sarcomas that are our Institutional experience in 29 years. The first case was a teenager of 14 years-old with a low grade leiomyosarcoma surgically treated. Along a 22 years follow-up the disease has had four local recurrences of more than 5 cm each one: two after surgery and two after surgery plus chemotherapy and surgery plus radiotherapy respectively. She is alive disease evidence after two years from the last combined treatment. The second one, was a 26 years-old patient with a malignant schwannoma of 12 cm in diameter treated with combined radical surgery, radiotherapy, and chemotherapy. She is alive and without disease evidence 52 months after surgery. We emphasized that these tumors are very rare and the fact that the first patient is the youngest and with more years of follow up according the bibliography consulted. Treatment of vulvar sarcomas is radical local excision followed mainly by radiotherapy with infiltrating margins. The value of postoperative adjuvant chemotherapy is uncertain. According to the natural history and behavior of vulvar sarcomas, we conclude that the elective treatment of these tumors should be carry out in institutions of high level.

Intensity modulation with the "step and shoot" technique using a commercial MLC: a planning study. Multileaf collimator

PURPOSE/OBJECTIVE

For complex planning situations where organs at risk (OAR) surrounding the target volume place stringent constraints, intensity-modulated treatments with photons provide a promising solution to improve tumor control and/or reduce side effects. One approach for the clinical implementation of intensity-modulated treatments is the use of a multileaf collimator (MLC) in the "step and shoot" mode, in which multiple subfields are superimposed for each beam direction to generate stratified intensity distributions with a discrete number of intensity levels. In this paper, we examine the interrelation between the number of intensity levels per beam for various numbers of beams, the conformity of the resulting dose distribution, and the treatment time on a commercial accelerator (Siemens Mevatron KD2) with built-in MLC.

METHODS AND MATERIALS

Two typical, clinically relevant cases of patients with head and neck tumors were selected for this study. Using the inverse planning technique, optimized treatment plans are generated for 3-25 evenly distributed coplanar beams as well as noncoplanar beams. An iterative gradient method is used to optimize a physical treatment objective that is based on the specified target dose and individual dose constraints assigned to each organ at risk (brain stem, eyes, optic nerves) by the radiation oncologist. The intensity distribution of each beam is discretized within the inverse planning program into three to infinitely many intensity levels or strata. These stratified intensity distributions are converted into MLC leaf position sequences, which can be subsequently transferred via computer link to the linac console, and can be delivered without user intervention. The quality of the plan is determined by comparing the values of the objective function, dose-volume histograms (DVHs), and isodose distributions.

RESULTS

Highly conformal dose distributions can be achieved with five intensity levels in each of seven beams. The merit of using more intensity levels or more beams is relatively small. Acceptable results are achievable even with three levels only. On average, the number of subfields per beam is about 2-2.5 times the number of intensity levels. The average treatment time per subfield is about 20 s. The total treatment time for the three-level and seven-beam case with a total of 39 subfields is 13 min.

CONCLUSION

Optimizing stratified intensity distributions in the inverse planning process allows us to achieve close to optimum results with a surprisingly small number of intensity levels. This finding may help to facilitate and accelerate the delivery of intensity-modulated treatments with the "step and shoot" technique.

[Malignant schwannoma of the neck]

Malignant schwannoma (MS) is a tumor of the peripheral nervous system, extremely rare when settled in head and neck. Conversely these two are preferable locations for benign schwannomata. We report a feminine patient, 74-year-old, with a right laterocervical massa, evolving in 3 months, surgically removed and postoperative radiotherapeutic treatment, which remains asymptomatic since one year and a half.

[Neurilemmoma of the nasal cavity and paranasal sinuses (report of 12 cases)]

OBJECTIVE

To further understand the neurilemmoma of nose.

METHOD

12 cases of neurilemmomas of the nasal cavity and paranasal sinuses were treated successfully by operation, 2 cases of malignant change lesions were treated by extensive resection and radiation.

RESULT

11 in 12 cases were followed up. 9 cases were cured and no any serious complications, 2 cases of malignant tumor were died.

CONCLUSION

Early stage diagnosis is important. CT scan should be made as essential examination, complete surgical resection is the choice of treatment for primary lesions; malignant change lesions should be treated by combined operation with radiation.

Hypofractionated radiation therapy of brain masses in dogs: a retrospective analysis of survival of 83 cases (1991-1996)

There are few reports of radiation treatment for brain tumors in dogs, and the optimal treatment protocol has yet to be established. We completed a retrospective analysis of the survival times of a series of 83 dogs with intracranial masses that were treated by hypofractionated megavoltage radiation therapy. A total tumor dose of 38 Gray was given over 5 weeks as once weekly fractions via 3 perpendicular portals. The median survival time from the start of radiotherapy for the whole cohort was 43.7 weeks (range, 0.1-172 weeks). Extra-axial masses had a better survival time (49.7 weeks) than did other intracranial masses (intra-axial, 40.4 weeks; pituitary, 21.0 weeks). Delayed radiation toxicity was suspected as the cause of death or reason for euthanasia in 12 dogs. The hypofractionated radiation protocol resulted in survival times similar to those obtained using more conventional multifractionated regimens, and this protocol may be a useful, less intensive alternative treatment for brain tumors in dogs.

[Fractionated irradiation of cerebellopontine angle neurinoma: 12 years' experience of the Bordeaux University Hospital Center]

PURPOSE

To evaluate retrospectively the long-term results of fractionated radiation therapy (RT) in cerebello-pontine angle neurinomas (CPA).

METHODS AND MATERIAL

From January 1986 to October 1995, 29 patients with stage III and IV neurinomas were treated with external fractionated RT. One patient was irradiated on both sides and indications for RT were as follows: (1) general contraindications for surgery (16 patients); (2) hearing preservation in bilateral neurinomas after controlateral tumor exeresis (six patients); (3) partial tumor removal (five patients); and, (4) non-surgical recurrence (three patients). A three to four fields technique with coplanar static beams and conformal cerobend blocks was used; doses were calculated on a 95 to 98% isodoses and were given five days a week for a median total dose of 51 Gy (1.8 Gy/fraction). Most patients were irradiated with 6 to 10 MV photons).

RESULTS

Median follow-up was 66 months (seven to 120 months). Seven patients died, two with progressive disease, five from non-tumoral causes. Tumor shrinkage was observed in 13 patients (43.3%), stable disease in 14 (46.6%), and tumor progression in three. Two patients underwent total tumor removal after RT (one stable and one growing tumor). Hearing was preserved in four out of six patients. No patient experienced facial or trigeminal neuropathy.

CONCLUSION

Fractionated RT is a well tolerated and efficacious treatment of large non-surgical CPA neurinomas.