MRI-guided stereotactic biopsy in the diagnosis of glioma: comparison of biopsy and surgical resection specimen

BACKGROUND: Although there has been a dramatic increase in the accessibility and utilization of high-resolution MRI techniques for the evaluation of brain tumors, there is currently only a single report comparing stereotactic brain biopsy specimen to subsequent resection specimen exclusively in the management of gliomas. METHODS: The diagnoses in 43 cases of astrocytic brain tumors were derived using MRI-guided stereotactic biopsy followed by open resection of the lesion. The histologic diagnoses yielded by biopsy were compared with subsequent histologic diagnosis after open tumor resection. All biopsies and histologic diagnoses were made by the same surgeon and pathologist, respectively. RESULTS: In 23 patients undergoing resection <60 days after biopsy, the biopsy diagnosis was consistent with resection diagnosis in 18 cases (79%) and led to the correct treatment in 22 cases (96%). Recurrent glioblastoma multiforme (GBM) was undergraded as anaplastic astrocytoma in 4 patients. GBM was misdiagnosed as radiation necrosis in 1 patient. MR-nonenhancing lesions [10/10 (100%)] yielded histology that correlated with subsequent craniotomy, while only 8/13 (61%) MR-enhancing lesions yielded histology that was consistent with that at craniotomy (p < 0.05). In 20 patients undergoing resection because of radiologic tumor progression (mean 7 months after biopsy), 6/6 (100%) biopsy diagnoses of a specific glioma grade correlated with resection diagnosis, while only 6/14 (43%) biopsy diagnoses of radiation effect correlated with resection diagnosis (p < 0.01). CONCLUSION: MRI-guided stereotactic brain biopsy specimen accurately represents the grade of the larger glioma mass sufficiently to guide subsequent therapy. Enhancement on MR may be a negative prognostic indicator of biopsy accuracy.     

Pineal region tumours treated with interstitial brachytherapy with low activity sources (192-iridium)

Summary Three patients with tumours of the pineal region underwent interstitial Ir-192 brachytherapy. Histological diagnoses were obtained in all patients, by stereotactic biopsy and included one germinoma, one mixed pineoblastoma/pineocytoma, and one astrocytoma grade III. Our approach to pineal region neoplasms is first to decide whether sterotactic biopsy or surgery should be performed. When a pineal lesion is thought to be benign on the basis of imaging, such as benign teratoma, surgery is performed to resect the entire lesion. When a definitive diagnosis is not possible, stereotactic biopsy is performed to obtain a histological diagnosis for treatment planning, using a Brown-Roberts-Wells (BRW) stereotactic apparatus with computed tomography (CT) or magnetic resonance imaging (MRI). When a lesion is malignant and localized, stereotactic implantation of catheters for interstitial brachytherapy is performed simultaneously. Radioactive Ir-192 seeds are inserted into the catheters and maintained for 5–10 days to give 36 Gy of irradiation at the tumour periphery. Sequential CT scans and MRI after treatment revealed tumour disappearance in two patients with germinoma and high grade astrocytoma and tumour reduction in the patient with mixed pineoblastoma/pineocytoma. No significant morbidity or mortality occurred in any of these patients after stereotactic biopsy and brachytherapy. The technique and the advantages of this therapeutic approach to selected pineal region tumours are described and discussed.     

Stereotactic biopsy of brain stem lesions.

The successful therapy of space-occupying lesions of the brain stem, depends on precise histological diagnosis. Although the clinical management and contemporary imaging techniques (computerized tomography and magnetic resonance imaging) are now able to reveal and approach the diagnosis in these cases, only the combination of these two with the use of contemporary stereotactic systems, is able to secure the precise histological diagnosis for the patient with a good degree of safety. This study presents the first five patients in Greece with space-occupying lesions of the brain stem, in whom a stereotactic biopsy was carried out. All patients were subjected to CT-guided stereotactic biopsy, via the frontal approach in 4 patients with lesions in the superior pons and the mesencephalon and in one patient via the transcerebellar approach, for a lesion in the lateral surface of the pons. Precise histological diagnosis was possible and on the basis of a reliable choice of histological criteria the appropriate therapeutic approach was chosen, thus avoiding the old "empirical" treatment.     

Stereotactic biopsy in the diagnosis of brain masses: comparison of results of biopsy and resected surgical specimen

We report the pathological accuracy of image-directed stereotactic brain biopsy in 30 patients who had mass lesions of the brain and subsequently underwent resection of the mass. The histological diagnosis at stereotactic biopsy was appropriate for direction of clinical management in 28 of 30 patients. Correlation between the stereotactic and resection diagnoses was exact in 19 of 30 cases. These included 11 of 12 nonastrocytic neoplasms and 8 of 13 astrocytic neoplasms. Correlation was imperfect in 9 of 30 cases, but not to the extent of having significant clinical impact. These included 2 cases of anaplastic astrocytoma that were upgraded to glioblastoma multiforme, 2 cases of astrocytoma that had a significant oligodendroglial component, and 5 non-neoplastic lesions that were reported on biopsy as showing nonspecific reactive changes. In 2 of 30 patients, the stereotactic biopsy was not accurate. This included one patient who had glioblastoma multiforme whose stereotactic biopsy showed only necrotic tissue. Serious diagnostic error that resulted in clinical mismanagement occurred in one patient who had a pineal germinoma that had large areas of granulomatous inflammation at which the stereotactic biopsy was directed. This study provides evidence that, with careful target placement, stereotactic biopsy can provide biopsy material that represents the entire lesion with an accuracy that is sufficient for clinical management.     

Primitive neuroectodermal tumour arising within low grade astrocytoma: transformation, de novo or radiation induced? Report of three cases and review of literature

The transformation from low grade to aggressive astrocytoma is well known. However, the development of a completely different tumour such as a primitive neuroectodermal tumour (PNET) within a low grade astrocytoma (LGA) is rare. Only two cases have been reported to date. We present three cases and review the literature. One case was identified at presentation. A subsequent review of our histopathology database revealed two further cases. All three patients had histologically proven low-grade astrocytoma and received radiotherapy following biopsy. The tumour location was infratentorial in one and supratentorial in two. The mean age at presentation with initial tumour was 20 years. Two patients underwent partial resection for recurrence, one at five and the other ten years later with histological confirmation of low-grade astrocytoma. At subsequent recurrence eight and thirty years following original presentation and eleven years later for the third patient, further tumour debulking was performed. Histology now revealed high grade PNET. Cytogenetics showed a complex karyotype with multiple chromosomal abnormalities in all three patients. All patients died within 1 year of final surgery. Among the six reported cases of PNET arising following prophylactic radiation therapy to low grade astrocytomas, only two occurred within the original tumour. Whether these cases represent transformation of low-grade astrocytoma, de novo formation of new tumour or radiation induced neoplasm is uncertain.     

Diagnosis and management of pediatric brain-stem gliomas

The authors reviewed the cases of 49 children, ranging in age from 9 months to 15 years, who were diagnosed by computerized tomography (CT) as having brain-stem glioma. Four distinct groups of brain-stem gliomas were identified based on CT scan characteristics: Group I included isodense contrast-enhancing tumors that were dorsally exophytic into the fourth ventricle; Group II(a) included hypodense nonenhancing intrinsic tumors of the brain stem; Group II(b) included intrinsic tumors of the brain stem with hyperdense exophytic components extending ventrally and laterally into the cerebellopontine and prepontine cisterns; Group III included intrinsic cystic tumors with contrast-enhancing capsules; and Group IV included focally intrinsic tumors of the brain stem that were isodense and enhanced brightly on administration of contrast medium. The clinical presentation, efficacy of surgical intervention, pathology, and prognosis of these tumors were correlated within these groupings. Eleven patients had Group I tumors, all of which were surgically resected; 10 of the 11 lesions were proven to be low-grade gliomas. These patients had an excellent prognosis; 10 of the 11 survived, with a mean follow-up period of 4.5 years. There were 18 patients with Group II(a) tumors; although tumor biopsy was attempted on eight of these, pathological diagnosis at the time of surgery was made in only one case. These patients did poorly; the mean survival time was 6.2 months. The seven Group II(b) tumor patients demonstrated a similarly poor prognosis: all of them died within 23 months of diagnosis, with a mean survival time of 12 months. Only two of six patients undergoing biopsy had sufficient tissue for histological verification. Three of the four patients with Group III tumors died; their mean survival time was 11.5 months. Successful histological examination was carried out in all four cases. The nine Group IV tumor patients did reasonably well; seven of these patients remain alive, with a mean follow-up period of 2.3 years. Histological diagnosis was obtained in three of the seven patients who were explored in this group. This classification system has proven to be of value in determining prognosis and efficacy of surgical intervention.     

Is it appropriate to redefine the indication for stereotactic brain biopsy in the MRI Era? Correlation with final histological diagnosis in supratentorial gliomas.

BACKGROUND: The aim of this study was to evaluate the advisability of modifying the indications for stereotactic brain biopsy (SBB) in high- and low-grade supratentorial glial tumors in correlation with the diagnostic accuracy of magnetic resonance imaging (MRI). MATERIALS AND METHODS: We analyzed 174 cases of supratentorial glial lesions diagnosed by MRI before biopsy. On the basis of the MRI findings the patients were divided into two groups: high-grade (n=107) and low-grade (n=67) gliomas. All patients underwent CT-guided biopsy. Only one preoperative diagnosis was allowed. RESULTS: A final histological diagnosis was achieved in 95% of the 174 cases. In the group of high-grade gliomas (HGG) there was diagnostic coincidence in 87% of cases, reaching 100% in lesions of the corpus callosum. In 11 cases (10%) the histological analysis changed the presumptive diagnosis and the consequent management. In the group of low-grade gliomas (LGG) there was diagnostic coincidence in 63% (42 cases), whereas there was discordance in 30%: 10 cases were upgraded to anaplastic astrocytoma, and in 10 cases no tumors were observed at all. CONCLUSIONS: In the future, the histological diagnosis of glial tumors will include molecular genetic definition, thus making it crucial for management using the new therapeutic options. Today, the indications for biopsy in lesions mimicking high-grade gliomas are mainly linked to the site of the tumor, coexisting differential diagnoses or more than one treatment option. In lesions of the corpus callosum, histological analysis seems not to be required in order to proceed to complementary therapies. On the contrary, in lesions where MRI findings indicate low-grade gliomas, grading is crucial also in order to avoid treatment inappropriate in non-neoplastic lesions.     

Molecular analysis of astrocytoma associated with Turcot syndrome type 1--case report

A 49-year-old man presented with a brain tumor and colon carcinoma. The patient had been treated under diagnoses of hereditary non-polyposis colorectal cancer syndrome and Muir-Torre syndrome. Magnetic resonance imaging revealed a mass lesion in the right frontal lobe with diffuse high intensity on T2-weighted and fluid-attenuated inversion recovery images. A few small lesions were enhanced by gadolinium on the T1-weighted images. Histological examination revealed the brain neoplasm was astrocytoma grade III according to the World Health Organization classification. Molecular genetic analysis detected microsatellite instability and p53 mutation only in the tumor tissue, indicating a failure of the deoxyribonucleic acid mismatch repair system. These results suggest that inactivation of mismatch repair system and p53 is closely associated with the tumorigenesis of this neoplasm. The final diagnosis was Turcot syndrome type 1.     

Classification of Severe Head Injury Based on Magnetic Resonance Imaging

OBJECT: In 1991 a new pioneering classification of severe head injuries had been proposed, based on CT findings. Unfortunately CT cannot visualise all lesions. Especially brain stem lesions may escape CT in spite of modern equipment, but may be demonstrated by MRI. The high incidence of CT negative but MRI positive posttraumatic brain stem lesions has already been demonstrated in a limited number of cases. A statistically significant evaluation is still missing. Therefore we have investigated a series of 102 comatose patients, in whom a statistical evaluation of MRI findings and their correlation with mortality and outcome of survivors was possible. PATIENTS AND METHODS: MRI was obtained within 8 days after servere head injury in 102 patients with a minimum of 24 hours of coma. The location of the lesions. identified by a neuroradiologist who was unaware of the clinical findings, was correlated with mortality, outcome of surviors and duration of coma. The correlation was analysed statistically. Follow-up ranged from 3 months to 3 years with a mean of 22 months. Four groups of lesions gave significant correlations: Grade I lesions were lesions of the hemispheres only; Grade II lesions were unilateral lesions of the brain stem at any level with or without supratentorial lesions; Grade III lesions were bilateral lesions of the mesencephalon with or without supratentorial lesions. Grade IV lesions were bilateral lesion of the pons with or without any of the foregoing lesions of lesser grades. RESULTS: Mortality increased from 14% in grade I lesions to 100% in grade IV lesions. The Glasgow outcome score differed significantly for each grade. The mean duration of coma increased from 3 days in grade I patients to 13 days in grade III. The correlations between the lesions grade I to IV with mortality, outcome of survivors and duration of coma were highly significant. CONCLUSION: The statistically significant correlations between the 4 groups of severe head injury patients, as identified by MRI, with mortality and outcome of survivors justify a new classification based on early MRI findings.     

Needle biopsy under computerized tomographic control: a method for tissue diagnosis in intracranial lesions

Thirteen patients with intracranial lesions were submitted to a twist drill needle biopsy under computerized tomographic (CT) control, with sedation and local anesthesia. (The patients' ages ranged from 12 to 81 years.) The final diagnoses were glioblastoma in 7 patients and 1 case each of anaplastic astrocytoma, low grade astrocytoma, thrombosed arteriovenous malformation, cerebral infarct, 3rd ventricular epidermoid, and degenerative disease of the brain. Definitive diagnosis was obtained in all but 2 patients with this technique. Appropriate therapy was subsequently instituted in 11 patients without further operation. Transiently increased weakness of the previously affected limbs was the only untoward effect (4 patients). Intracranial hematoma after this procedure was seen in 1 patient in this series, as detected by the postprocedure CT scan, but there was no change in the clinical course. All patients were treated with dexamethasone for 24 to 48 hours before and for several days after the procedure to avoid decompensation of intracranial dynamics because of edema. The procedure, including appropriate level CT scans of the lesion area, was performed in approximately 1 hour in all patients. (Neurosurgery, 5: 671--674, 1979).     

Frequency of positive biopsies after visual disappearance of superficial bladder cancer marker lesions.

INTRODUCTION AND OBJECTIVES: In phase II trials in superficial bladder cancer, marker lesions have been used to test the ablative activity of intravesical chemo- or immunotherapy. These studies provide important knowledge about drug activity and toxicity without exposing hundreds of patients in phase III trials to drugs which ultimately may not be successful in preventing tumour recurrence or progression. After treatment a deep biopsy was necessary at the site of the marker lesion even in the absence of any visual tumour. The question is if this biopsy, in the absence of any visual tumour, should be done. MATERIAL AND METHODS: The ablative effect of MMC, epirubicin, and quarter dose BCG instillations was evaluated in three different studies on a papillary marker lesion. Patients with multiple, primary or recurrent superficial bladder tumours were included. All visible Ta-T1 lesions were resected except for one marker lesion not exceeding 1 cm. TIS was excluded. In the last study, patients with T1 G3 tumours or multiple tumours >10 were also excluded. If the marker lesion disappeared completely, a deep biopsy was performed at the scar in order to prove histological disappearance of the tumour. RESULTS: 185 patients were evaluated. No visual tumours were seen in 110 patients and a TUR was performed in 101 of them. It revealed only 3 Ta lesions. In the 9 others no biopsy was performed but follow-up cystoscopy revealed no lesions. CONCLUSIONS: In the absence of any visual tumors, TUR and deep biopsy at the site of the scar of the marker lesion only rarely revealed (3 out of 110) the histological presence of a tumour. Therefore, this biopsy can be omitted in new marker lesion protocols in patient with Ta-T1, G1 G2 papillary superficial bladder tumours at intermediate risk for recurrence and low risk for progression.     

Radiation-induced astrocytoma with rapid malignant transformation: case report

A 23-year-old man was admitted with a rare case of radiation-induced astrocytoma manifesting as 3-month history of unstable gait. He had received 50 Gy of irradiation therapy for a germ cell tumor in the right basal ganglia 13 years earlier. Magnetic resonance (MR) imaging on admission showed a non-enhanced mass lesion in the right cerebellar hemisphere with expansion to the vermis. The histological diagnosis of the stereotaxic biopsy specimen was grade II astrocytoma. Two months later, he developed drowsiness, and MR imaging demonstrated that the tumor had enlarged and was enhanced after gadolinium injection. The clinical diagnosis was high-grade glioma resulting from malignant transformation. The tumor had compressed the mesencephalic aqueduct, leading to obstructive hydrocephalus. Endoscopic third ventriculostomy was performed to improve the cerebrospinal fluid circulation. He underwent chemotherapy with temozolomide postoperatively, but died 8 months after the initial diagnosis of astrocytoma. The clinical course of radiation-induced astrocytoma is not benign. The potential for malignant transformation necessitates careful postoperative follow up for patients with this tumor.     

Image directed stereotactic surgery for brain stem lesions

Summary Advances in neurological imaging may have increased the diagnostic accuracy and the detection rate of intrinsic brain stem lesions, but a histological diagnosis is still an essential requirement for rational and appropriate management. Open exploration allows biopsy and resection in cases where an exophytic component is present. The surgical inaccessibility and the resultant morbidity of these approaches, however, associated with a low diagnostic yield in cases with no visible surface abnormality, are important limiting factors.A series of 45 brain stem lesions stereotactically approached with CT or MRI guidance is presented. A transcortical frontal pre-coronal trajectory was used in all of them. Haematoma was preoperatively diagnosed in 10 cases and the procedure was for therapeutic aspiration. Of 35 cases where the diagnosis was uncertain, although intrinsic tumour was suspected, positive results were obtained in 33, while unexpected findings of granuloma, lymphoma, angioma, leucoencephalopathy, vasculitis and radiation necrosis were found in over 10% of the cases. There were no operative deaths and the morbidity was low. In no case was there a permanent neurological deterioration directly related to the procedure, although there was a transient deterioration in two patients and one patient required early reaspiration of a haematoma.Image directed stereotactic approaches to brain stem lesions can combine a high degree of accuracy (offering positive histological diagnoses) with a low operative morbidity. MRI directed biopsies can complement CT guided ones thus increasing the number of suitable cases and improving the success rate. The frontal precoronal transcortical trajectory provides safe access to the majority of the brain stem targets.Invited Lecture, presented at the European Congress of Neurosurgery, Moscow, June 23–29, 1991.     

Accuracy of stereotactic brain tumor biopsy: Comparison of the histologic findings in biopsy cylinders and resected tumor tissue

Appropriate treatment for intracranial mass lesions depends upon accurate morphological diagnosis. In 47 of 360 patients the findings in stereotactically obtained tissue cylinders were compared with tumor resection (n=38) or autopsy (n=9) tissue material to define the accuracy of our stereotactic biopsy method. These biopsies were performed using the LEKSELL CT stereotactic frame and a spiral needle which procured about 10-mm-long tissue cylinders. Usually, three to four successive biopsy specimens were taken along the target trajectory placed through the whole lesion and its margins according to the CT imagings. Final morphological diagnosis was exclusively based on the histological findings of permanent paraffin sections.In 42 cases (89%), the histological results in biopsy and resection/autopsy tissue were identical, including mainly cases of low and high grade gliomas as well as some brain lymphomas, metastases, and cases of inflammatory brain lesions (aspergillosis, toxoplasmosis). In 3 patients with a diagnosis of brain lymphoma and low grade glioma on the basis of the surgical specimens, stereotactic biopsy revealed only unspecific reactive tissue changes. In two cases of the early part of the study, sampling errors occurred. This study provides evidence for the high diagnostic accuracy of the established stereotactic biopsy method which is characterized by representative tissue sampling and histological processing of the specimens.     

Stereotactic biopsy of brain stem masses: Decision analysis and literature review

BACKGROUND: Adult brain stem tumors are rare, and diverse pathology can be found in this location. Stereotactic biopsy of lesions in the brain stem has been performed since the 1960s with high diagnostic and low complication rates. Advances in imaging technology have raised questions regarding the utility of biopsy. We perform decision analysis to aid clinicians in their approach to management of adult brain stem lesions. METHODS: A structured literature search revealed 20 publications with 457 patients who had undergone brain stem lesion biopsy. These publications were reviewed to determine diagnostic rates and the incidence of complications. Standard decision analytic techniques were applied to the case of a virtual adult patient with a lesion in the brain stem. RESULTS: A 1-way sensitivity analysis revealed the likelihood that the preoperative diagnosis was correct and the rate at which incorrect treatment was based on faulty empirical diagnosis as the 2 factors with the greatest effects on patient outcome. The diagnostic rate and complication rate of biopsy, within the ranges reported in the literature, had lesser effects. A threshold analysis was constructed to compare outcomes from stereotactic biopsy vs empiric therapy for a brain stem lesion. The probability that the preoperative diagnosis is correct is plotted vs the probability that empirical treatment based on an incorrect diagnosis will have adverse effect. CONCLUSIONS: Management of lesions in the adult brain stem requires careful consideration of multiple preoperative factors including clinical and radiographic diagnostic certainty, consequences of empiric therapy, and the surgeon's complication rate.     

Surgical approach to pineal tumours

During a period of 10 years (1977-1986) 40 cases of tumour of the pineal region have been treated at the Istituto Neurologico "C. Besta"-of Milan. Out of these 40 cases, 27 (67.5%) were in the paediatric (10-15 years) or juvenile (15-20 years) age at the time of operation. Since 1983 a specific diagnostic and therapeutic protocol has been adopted and thereafter direct surgical removal of the tumour was performed only when the neuroradiological investigations were highly suggestive of a benign extrinsic lesion. Sixteen cases in this series underwent direct surgical removal; in the remaining 24 cases stereotactic biopsy of the tumour was performed in the first instance. On the basis of the histological diagnosis obtained by this procedure surgical excision of the tumour (9 cases) or radiotherapy (15 cases) was then performed. 25 cases underwent surgical removal of the lesion. In all the cases the infratentorial supracerebellar approach as introduced by Krause and then modified by Stein was adopted. On analysis of the data of this series it was observed that in 25% of the cases completely benign resectable tumours were found; in 25% of the cases astrocytoma (grade I-II) which could be treated at least by partial removal were present; in 30% of the cases radiosensitive lesions were encountered. In the remaining 20% of the cases highly malignant tumours were found which should be treated only by radiotherapy and/or chemotherapy.     

Multicentric malignant glioma.

Multicentre gliomas are a well recognized entity but the occurrence of such tumours both above and below the tentorium remains uncommon. We report the case of an 11-year-old boy who underwent stereotactic biopsy of a brain stem ring enhancing tumour with histology of an anaplastic astrocytoma (Grade 3). Nine months following his radiotherapy a large left frontal mass was biopsied and found to be a malignant glioma (Grade 4). Advances in neuroradiological imaging will readily show multiple cerebral lesions and multicentre glioma should be considered in the differential diagnosis of such lesions and biopsy is indicated.     

Lytic bone lesions in an Australian population: the results of 100 consecutive biopsies

BACKGROUND: The identification of a lytic bone lesion is often perceived as a harbinger of malignancy, especially in an older patient. This study reviews the results of 100 consecutive biopsies of patients who presented with either a solitary lesion or multiple lytic bone lesions in the absence of a history of malignancy. METHODS: Following preoperative planning, including plain radiographs, bone scan and computed tomography scanning, an open biopsy was carried out. RESULTS: The most common site affected was the pelvis (20 patients), followed by the femur (19) and tibia (15). The lesions were solitary in 88 patients and multiple in 12. The most common diagnosis was a secondary carcinoma presenting as a bone lesion, which was found in 25 patients. The carcinomas were a widely distributed group, but the most common among them were renal cell carcinoma (seven patients), breast carcinoma (five patients) and lung carcinoma (five patients). The most common primary bone tumour was a giant cell tumour (16) followed by myeloma (10). Multiple lesions were not universally an indication of a malignant process. In 14 patients the lesion was not a tumour. CONCLUSION: This study emphasizes the importance of obtaining a tissue diagnosis.     

Biopsy procedures, primary wide excisional surgery and long term prognosis in primary clinical stage I invasive cutaneous malignant melanoma.

281 patients managed for primary clinical Stage I invasive cutaneous malignant melanoma at one Plastic Surgery Unit were followed up to a minimum of 10 years after primary surgical treatment. Sixty-three (23%) had received an initial biopsy procedure prior to definitive wide margin excisional surgery. One third of all lesions initially treated by so called incisional biopsy were rendered histologically unassessable on current histopathological criteria. Incisional biopsy significantly interfered with the accurate histopathological staging of the tumours. Of the assessable incisional biopsy specimens the majority were greater than 4.0 mm thick. When the incidences of local tumour recurrence and mortality were related specifically to maximal tumour thickness of the primary lesion, prognosis at minimum follow up of 10 years was not significantly different between patients treated initially by either incisional biopsy, minimal margin excisional biopsy or primary wide excisional surgery. Whether or not incisional biopsy adversely affects prognosis in cutaneous malignant melanoma, the technique should be avoided since it compromises accurate histopathological microstaging which represents one of our most valuable prognostic guides. Clinical doubt over the diagnosis of cutaneous malignant melanoma should be resolved by a total excisional biopsy of the lesion in question.     

Acute demyelination: diagnostic difficulties and the need for brain biopsy

Summary ¶Background. Despite the rapid development in neuro-imaging over the past two decades, ring like contrast-enhancing lesions on CCT or MRI still may pose a diagnostic challenge. The main differential diagnoses of these lesions include metastatic carcinoma, high-grade glioma and brain abscess. Acute demyelination seldom turns out to be the underlying pathology. Method. Retrospective analysis was done on six patients with acute demyelination treated at our neurosurgical department between 1990 and 2001. Clinical, radiological, PET, intra-operative and histological findings were evaluated. Findings. In five patients, the diagnosis of acute demyelination was established by histopathological evaluation of stereotactic biopsy specimen, in the sixth patient following microsurgical extirpation of the lesion. Neuropathology revealed demyelination with the presence of myelin-phagocytosing macrophages. In addition, lymphocytic infiltrates were present. Symptoms and signs improved significantly after high-dose steroid therapy. Conclusions. Despite CNS tissue destruction, necrosis and cyst formation are not usually found in demyelinating disease, being rather more common in young patients with ring-like contrast-enhancing lesions on CCT and MRI. Though an incorrect diagnosis can lead to a potentially fatal therapeutic intervention, histological diagnosis should be made in all cases. Due to minimum morbidity, stereotactic biopsy is the method of choice to obtain representative specimens for histological diagnosis. Open microsurgery of these lesions is not indicated since conservative medical treatment with steroids results in a favourable outcome in most cases.Published online October 13, 2003