Molecular genetic studies of tumor suppressor gene regions on chromosomes 13 and 17 in colorectal tumors.

BACKGROUND: In the majority of colorectal carcinomas, both copies of the tumor suppressor gene TP53 (tumor protein 53) are known to be inactivated. In contrast to a loss of tumor suppressor function, it has been suggested that an increased copy number of the RB1 gene is involved in the progression of these tumors. PURPOSE: To determine genetic alterations at chromosomes 13 and 17 in colorectal tumors, we have studied several loci on these chromosomes, with special focus on the RB1 and TP53 genes at both the level of DNA sequence and the level of gene expression. METHODS: Restriction fragment length polymorphism analysis was performed after alkaline Southern blotting of the DNA fragments and hybridization (in 7% sodium dodecyl sulfate and 0.5 M NaPO4) of the nylon membranes with multiprimed, radioactively labeled probes. Total RNA was extracted from tissue biopsy specimens by homogenization of the samples in guanidinium thiocyanate followed by separation in a CsCl gradient. By use of an image-processing system, x-ray film signals were measured densitometrically. Point mutations within the TP53 gene were detected by use of polymerase chain reaction (PCR) in combination with constant denaturant gel electrophoresis. Direct sequencing of PCR products revealed the exact nature of the mutations. Protein expression of TP53 was seen by immunostaining of sections from paraffin-embedded material using a mouse monoclonal antibody. The two-sided Fisher's Exact Test was used for statistical analysis. RESULTS: An increase in allelic copy number at 13q loci was seen in 10 (32%) of 31 tumors. In the majority of the cases, this increase probably reflected a change in the diploid status of chromosome 13; in some cases, however, only part of the 13q seemed to be involved. The RB1 gene showed an elevated level of RNA compared with the beta-actin signal. Fourteen (48%) of 29 tumors showed loss of heterozygosity at loci on 17p, and base mutations within the TP53 gene were seen in 14 (42%) of 33 tumors. RNA and protein analyses of TP53 revealed an increased level of expression in the tumors compared with normal mucosa. Allelic variations seen at 13q and 17p were not associated (P = .7). CONCLUSIONS: Our results suggest that, in addition to aneuploidy, gain of specific chromosome 13 sequences is involved in the tumorigenesis of the colon and rectum. In addition, they confirm the importance of TP53 mutations for the progression of such tumors and support the view that accumulation of events is more important than the order of events. The genetic changes observed at chromosome arms 13q and 17p seem to be independent of each other.

Expression and characteristics of a novel human osteosarcoma-associated cell surface antigen.

The characteristics of a new osteosarcoma-associated cell surface antigen were studied by means of two murine monoclonal antibodies, TP-1 and TP-3, which were found to bind to two different epitopes on the same antigen, a monomeric polypeptide with a molecular weight of approximately 80,000. Immunohistochemical studies showed that the antigen was present in all osteogenic sarcomas tested, in most cases of malignant fibrous histiocytoma, in two malignant hemangiopericytomas and in a few synovial sarcomas, but not in other main groups of sarcomas and nonsarcomatous malignancies. In normal tissues it was detected only in clusters of cells in the adrenal medulla and in proximal kidney tubules. Also endothelial cells in proliferating capillaries in placenta and in most tumors were stained. The antigen was absent in resting but present in actively proliferating osteoblastic cells. The epitopes were resistant to proteolytic and sugar-cleaving enzymes but sensitive to high temperatures and could not be detected in paraffin-embedded specimens. The tissue distribution and properties of the antigen show that it is different from the sarcoma-associated antigens previously studied. In contrast to previous findings with three other anti-sarcoma monoclonal antibodies, no correlation was found between serum alkaline phosphatase activity and the amount of TP-binding substances in the same sera. Nevertheless, an apparently complex association between alkaline phosphatase and the TP-binding antigen seems to exist. Thus, the Mr 80,000 antigen extracted from an osteosarcoma cell line showed enzyme activity, whereas TP-binding molecules precipitated from patient sera contained alkaline phosphatase activity only in a few of the cases studied. Altogether our data suggest that the antigen defined by the TP antibodies may be a marker of osteoblastic differentiation. The pattern of antigen expression in malignant tumors is unique, inasmuch as the antigen is found selectively in sarcomas and in all 31 osteosarcomas tested.

Somatic mutations in LKB1 are rare in sporadic colorectal and testicular tumors.

Germ-line mutations in a serine/threonine kinase gene, LKB1, were recently shown to underlie Peutz-Jeghers syndrome (PJS), a hereditary disorder that predisposes to benign and malignant tumors of multiple organ systems. Most mutations that have been described thus far dramatically change the predicted protein and are likely to be of an inactivating nature. This observation and a previous observation that the LKB1 locus is often deleted in PJS polyps suggest that the gene may function as a tumor suppressor. We examined whether somatic mutations in this gene are present in sporadic carcinomas of the colon and testis, tumors that are characteristic of PJS. First, 20 randomly selected colorectal and 28 testicular tumors were analyzed by single-strand conformation polymorphism analysis. No mutations in LKB1 were found in colorectal tumors. One testicular tumor displayed a heterozygous missense type variant, in which glycine 163 was changed to aspartic acid. This change was absent in the DNA of normal tissue. To better focus our efforts, we tested 75 additional colon carcinomas for loss of heterozygosity at 19p, where LKB1 is localized. Of 75 samples analyzed, 50 were informative with a closely linked marker, D19S886, and 13 (26%) of these displayed loss of heterozygosity. The 13 tumors were scrutinized for LKB1 mutations by genomic sequencing. This analysis revealed no changes. Together, these findings suggest that somatic mutations of LKB1 are not frequent in colorectal and testicular cancer.

Frequent promoter hypermethylation of the O6-Methylguanine-DNA Methyltransferase (MGMT) gene in testicular cancer.

Testicular germ cell tumours are classified into two major histological subgroups, seminomas and nonseminomas. All tumours display several recurrent chromosomal aberrations, but few target genes have been identified. Previous studies have shown that genome-wide hypermethylation of CpG islands is significantly more prevalent in nonseminomas than in seminomas. We have studied two potential target genes in testicular cancer. A series of 70 tumours were analysed for methylation of CpG sites in the O(6)-methylguanine-DNA methyltransferase (MGMT) gene promoter, and in exon 1alpha of the cyclin-dependent kinase inhibitor 2A gene (CDKN2A). In addition, eight microsatellite markers within and flanking these genes at chromosome arms 10q and 9p, respectively, were analysed for allelic imbalances. Allele alterations were frequently seen at 9p loci (47 out of 70, 67%), but none of the tumours (none out of 55) showed methylation of CDKN2A. On the other hand, a high frequency of MGMT promoter methylation (32 out of 69, 46%) was found, as well as allelic imbalances at 10q markers (50 out of 70, 71%). A significantly higher methylation frequency was found in nonseminomas (24 out of 35, 69%) compared to seminomas (eight out of 33, 24%) (P=0.0003, Fisher's exact test). Immunohistochemical analysis of the MGMT protein in a subgroup (n=20) of the testicular tumours supported the hypothesis of gene silencing being the functional consequence of the promoter methylation. In summary, our data suggest that inactivation of MGMT contributes to development of nonseminomatous testicular cancer.

Treatment of osteosarcoma of the extremities with the T-10 protocol, with emphasis on the effects of preoperative chemotherapy with single-agent high-dose methotrexate: a Scandinavian Sarcoma Group study.

From 1982 to 1989, 97 patients with extremity-localized, high-grade osteosarcoma were treated according to the T-10 protocol. Two thirds of the patients consisted of the near-complete national patient materials from Norway and Finland. Eighty patients (82%) received four courses of high-dose methotrexate (HD MTX, 8 to 12 g/m2) at weekly intervals as their only preoperative treatment, and 77 patients (79%) were assessable for histologic response grading according to Rosen et al (Cancer 49:1221-1230, 1991). Observed histologic response was no certain chemotherapy effect (grade I) in 21%, grade II effect in 62%, and grade III or IV effect in 17%. Nonresponders had significantly lower serum MTX concentrations after 24 and 48 hours than responders; the significance of the difference at 48 hours was maintained in a multivariate analysis. After a median follow-up of 45 months, projected 5-year overall and relapse-free survival for all patients were 64% and 54%, respectively. Patients with a good response to preoperative chemotherapy (grade III/IV) had a significantly better survival than grade I/II responders, despite a switch to postoperative cisplatin/doxorubicin chemotherapy in the latter group. These results were obtained in a largely nonselected group of patients. We conclude that a good initial chemotherapy effect is important for the final outcome in osteosarcoma, and that HD MTX alone is insufficient preoperative treatment for the majority of patients. The individual MTX excretion rate is of importance for tumor response, suggesting a dose-response relationship for HD MTX treatment.

Is postchemotherapy retroperitoneal surgery necessary in patients with nonseminomatous testicular cancer and minimal residual tumor masses?

PURPOSE: At least one third of the patients with metastatic testicular cancer are rendered tumor-free by cisplatin-based chemotherapy. One may question, therefore, the routine use of postchemotherapy retroperitoneal lymph node dissection (RLND), especially if the residual masses are less than 20 mm in diameter. To define the role of such surgery, we analyzed the postchemotherapy histology in testicular cancer patients with minimal residual disease. PATIENTS AND METHODS: Seventy-eight patients with advanced nonseminomatous testicular cancer underwent RLND after three to four cycles of cisplatin- or carboplatin-based chemotherapy. In all patients, the largest diameter of the residual retroperitoneal mass was less than 20 mm. RESULTS: Complete fibrosis/necrosis was found in 51 patients, mature teratoma in 22, and vital malignant germ cell tumor in five. In two of the latter five patients, alphafetoprotein (AFP) had increased immediately before RLND. In the 76 patients with normal pre-RLND tumor markers, the presence of undifferentiated malignant teratoma (MTU) in the primary tumor and normal prechemotherapy tumor markers were independent parameters predicting complete fibrosis/necrosis, which was demonstrated in all 15 patients with these two pretreatment parameters. CONCLUSIONS: Postchemotherapy RLND can be omitted in patients with MTU in the primary tumor who have normal AFP/human chorionic gonadotropin (AFP/HCG) before chemotherapy and whose residual retroperitoneal mass is less than 20 mm in diameter. If the pre-RLND tumor markers are normal, RLND should be performed in all other patients with small residual masses, even in the presence of a normal computed tomography (CT) and particularly if regular follow-up of the patients is not guaranteed.

The treatment of advanced metastatic seminoma: experience in 55 cases.

Thirty-six of 39 previously untreated evaluable patients with advanced metastatic seminoma (stage greater than or equal to IIb) obtained a complete response (CR) and three a partial response (PR) after cisplatin-based combination chemotherapy with or without surgery/radiotherapy (group 1). After a median observation time of 36 months, 33 patients are alive with no evidence of disease (NED). Fifteen additional patients received cisplatin-based chemotherapy due to relapsing seminoma after initial radiotherapy (group 2). Thirteen patients obtained a CR, and two a PR. Patients from group 1 lived significantly longer after the start of chemotherapy than those from group 2. The rate and severity of the treatment-related complications were comparable in both groups. The most frequent nonfatal side effects of cisplatin-based combination chemotherapy were Raynaud-like phenomena, polyneuropathy, and myelosuppression. Four patients developed fatal complications (septicemia, bone marrow aplasia). In three of 12 patients with evaluable postchemotherapy histology, vital malignant seminoma was found. Cisplatin-based combination chemotherapy in advanced seminoma patients is highly effective, but includes a significant risk of severe complications. Less toxic treatment regimens should be explored, at least for patients who have less advanced tumors (stage IIb/limited stage IIc).

Late recurrence of testicular cancer.

The aim of this study is to draw attention to important points concerning the clinical management of late relapses in testicular cancer. From 1972 to 1982 The Norwegian Radium Hospital (NRH) has treated 1,008 patients with testicular cancer. Fifteen (1.5%) of these patients relapsed 36 months or more after their primary treatment. The patients' medical records were reviewed in this retrospective study, and all available histological sections were reevaluated. Six patients had pure seminoma initially and relapsed after an average of 54.5 months. Five of them had subjective symptoms due to recurrent tumor. Four patients relapsing in the supradiaphragmatic lymph nodes only are alive with no evidence of disease after an observation time of 17 to 30 months after treatment. Nine nonseminoma patients relapsed after an average of 85 months (36 to 194 months). Eight of these were aware of subjective signs or symptoms due to recurrent tumor leading to the diagnosis of the relapse. Four of these patients are alive with no evidence of disease after an observation time of 4 to 46 months after treatment. Two of these patients relapsed with pure mature teratoma. Late relapses do occur although they are rare events. Seminoma patients relapsing in the lymph nodes only have a good prognosis, and nonseminoma patients have a slightly poorer prognosis. Active follow-up for relapse detection is not justified. All testicular cancer patients should instead be informed of typical signs and symptoms that can be related to a relapse and encouraged to seek medical help for further investigation.

Prognostic factors in clinical stage I nonseminomatous germ cell tumors of the testis: multivariate analysis of a prospective multicenter study. Swedish-Norwegian Testicular Cancer Group.

Between 1981 and 1986, 279 consecutive patients with clinical stage I (CS1) nonseminomatous germ cell tumors (NSGCT) of the testis underwent pathological staging (PS) with retroperitoneal lymphadenectomy (RPLND). Patients with retroperitoneal metastases (PS2) received adjuvant chemotherapy. The median follow-up time after RPLND was 50 months (range, 30 to 90). Clinical and histopathologic features were registered prospectively and analyzed for association with risk of having PS2, relapse despite pathological stage 1 (PS1) or the combined risk of either event, metastatic disease (MET). Seventy-five (26.9%) of the patients had PS2 disease, and 30 (14.7%) of the 204 PS1 patients relapsed, indicating that at least 105 (37.6%) of this CS1 population had subclinical MET at the time of orchiectomy. Four (1.4%) of the 279 CS1 patients died of testicular cancer. Multivariate analyses showed several variables to be significantly associated with outcome for the CS1 patients; vascular invasion in primary tumor and normal preorchiectomy serum alpha-fetoprotein (Pre-AFP) level indicated PS2 disease. If Pre-AFP was excluded from the model, the absence of teratoma or yolk sac elements in the primary tumor became significant predictors of PS2. Vascular invasion, absence of teratoma, and a short interval between orchiectomy and RPLND indicated increased risk of relapse in PS1 patients. Vascular invasion, normal Pre-AFP, absence of teratoma elements, and a short orchiectomy to RPLND interval were predictive of MET. Our results indicate that prognostic factors useful for stratification of CS1 patients with NSGCT to different treatment options may be established.

Familial/bilateral and sporadic testicular germ cell tumors show frequent genetic changes at loci with suggestive linkage evidence.

Testicular germ cell tumor (TGCT) is the most common tumor type among adolescent and young adult males. Familial clustering and bilateral disease are suggestive of a genetic predisposition among a subgroup of these patients, but susceptibility genes for testicular cancer have not yet been identified. However, suggestive linkage between disease and genetic markers has been reported at loci on chromosome arms 3q, 5q, 12q, 18q, and Xq. We have analyzed primary familial/bilateral (n=20) and sporadic (n=27) TGCTs, including 28 seminomas and 19 nonseminomas, for allelic imbalance (AI) within the autosomal regions. DNA from all tumors were analyzed by fluorescent polymerase chain reaction of 22 polymorphic loci at 3q27-ter, 5q13-35.1, 12q21-ter, and 18q12--ter. All tumor genotypes were evaluated against their corresponding constitutional genotypes. The percentages of TGCTs with genetic changes at 3q, 5q, 12q, and 18q, were 79%, 36%, 53% and 43%, respectively. The frequencies at 3q and 12q in nonseminomas were significantly higher than in seminomas (P=.003 and P=.004). In order to evaluate changes at hemizygous Xq loci, five loci were analyzed by co-amplification with an autosomal reference marker known to reveal retained heterozygosity in the tumor DNA. Gain of Xq sequences was seen in more than 50% of the tumors. The degree of amplification varied among the loci in each of five tumors, and based on these breakpoints, a common region of overlapping gains was found at Xq28. No significant differences were found between the frequencies of genetic changes in familial/bilateral versus sporadic tumors, an observation speaking in disfavor of the existence of a single susceptibility gene for TGCT in any of the analyzed regions. Our data suggest that gain of genetic material at distal Xq and losses at 5q and 18q contribute to establishment of seminomas, whereas imbalances at 3q as well as gain at distal part of 12q are associated with further progression into nonseminomas.

Prevalence and prognostic significance of epilepsy in patients with gliomas.

The aim of this study was to evaluate the prevalence and prognostic significance of epilepsy in 1028 patients diagnosed in the computer tomography (CT) era with histological low- or high-grade intracranial gliomas. Survival analysis included Kaplan-Meier plots, log-rank tests, logistic regression and Cox's analysis as implemented in the SPSS statistical package. Epilepsy was a positive univariate (P < 0.0001) and multivariate, (P < 0.03) prognostic factor for survival in the total patient group (n = 1028, relative risk of death 0.83, 95% confidence interval (CI) 0.70-0.98) as well as in the high-grade patient group (n = 649, relative risk of death 0.80, 95% CI 0.66-0.96), but not in the group of low-grade glioma patients (P > 0.2). The prevalence of epilepsy in glioblastoma patients was 251/512 (49%), 95/137 (69%) in anaplastic gliomas, and 322/379 (85%) in patients with low-grade gliomas, with 97 of the 102 T1 low-grade subgroup (95%) having epilepsy, indicating that the presence of epilepsy may select patients for early radiological diagnosis. The frequency of epilepsy at presentation decreased with age in high-grade glioma patients, and increased with age in low-grade glioma patients to a plateau in the fourth decade of life (P < 0.01). The prevalence of epilepsy in patients with histological intracranial gliomas varied with patient age and tumour histology, with low-grade patients having the highest prevalence. Epilepsy was a significant positive prognostic factor except in patients with low-grade gliomas, and may select low-grade patients for early diagnosis.

Scandinavian Sarcoma Group Osteosarcoma Study SSG VIII: prognostic factors for outcome and the role of replacement salvage chemotherapy for poor histological responders.

From 1990 to 1997, 113 eligible patients with classical osteosarcoma received neo-adjuvant chemotherapy consisting of high-dose methotrexate, cisplatin and doxorubicin. Good histological responders continued to receive the same therapy postoperatively, while poor responders received salvage therapy with an etoposide/ifosfamide combination. With a median follow-up of 83 months, the projected metastasis-free and overall survival rates at 5 years are 63 and 74%, respectively. Independent favourable prognostic factors for outcome were tumour volume < 190 ml, 24-h serum methotrexate > 4.5 microM and female gender. The etoposide/ifosfamide replacement combination did not improve outcome in the poor histological responders. In conclusion, this intensive multi-agent chemotherapy results in > 70% of patients with classical osteosarcoma surviving for 5 years. The data obtained from this non-randomised study do not support discontinuation and exchange of all drugs used preoperatively in histological poor responders. As observed in previous Scandinavian osteosarcoma studies, female gender appears to be a strong predictor of a favourable outcome.

Prognosis in patients with metastatic non-seminomatous testicular cancer.

155 patients with metastatic non-seminomatous testicular cancer were treated with cisplatin-based chemotherapy which in most cases was combined with surgery. The 5 year crude survival was 90% for all patients (98 patients with small volume disease: 97%; 32 patients with large volume disease: 91%; 25 patients with very large volume disease: 64%). High pre-chemotherapy serum tumour marker levels (AFP greater than 500 micrograms/l; and/or HCG greater than 1000 U/l) decreased the survival rates in all groups. Only 4 of 17 relapsing patients were rendered tumour-free by salvage chemotherapy. In a multivariate analysis, a pre-chemotherapy alpha-foetoprotein (AFP) level greater than 500 micrograms/l was associated with poor survival as was the presence of a retroperitoneal tumour greater than 10 cm, lung metastases greater than 3 cm and/or extrapulmonary hematogenous metastases. It is concluded that easily assessable clinical pre-treatment variables can be used to define high risk or low risk patients with metastatic testicular cancer. Treatment intensity should be adjusted in accordance to such prognostic factors.

Prognostic factors in patients with stage I epithelial ovarian cancer.

We analyzed factors predictive of relapse risk in patients with stage I invasive epithelial ovarian cancer: 252 patients from the Princess Margaret Hospital provided a data base for hypothesis generation, and data on 267 patients from the Norwegian Radium Hospital were used for hypothesis testing. The outcomes in most analyses in the two series were very similar, validating the following conclusions. Differentiation (grade) was the most powerful predictor of relapse, followed by dense adherence (which resulted in outcomes equivalent to those in stage II) and, finally, large-volume ascites. When the effects of these three factors were accounted for, then none of the following were prognostic: bilaterality (stage Ib), cyst rupture (stage Ic), capsular penetration (stage Ic), tumor size, histologic subtype, patient age, year of diagnosis, and postoperative therapy. These results allow simplification of stage I substaging, as only differentiation, dense adherence, and large-volume ascites (? peritoneal cytology) need be considered. The 5-year relapse-free rate was 98% in patients with grade 1 tumors in whom both dense adherence and large-volume ascites were absent. These patients are adequately treated by operation alone. Although the relapse risk was high enough in the remaining patients to warrant postoperative treatment, a significant benefit could be shown only for a small subset of patients, namely those with densely adherent tumors treated with abdominopelvic radiotherapy. In grades 2 and 3, none of the therapies used in either series was superior to pelvic radiotherapy or operation alone.

Loss of one chromosome #13 during development of a polyposis tumor.

A cell panel from six different familial cancers, where both normal and tumor tissues were available, was examined for genotypic changes with polymorphic DNA probes. Seventeen probes were tested, representing chromosomes #1, #2, #5, #6, #13, #14, #17, and #19. One probe, p7F12 (D13S1, at 13q12-q14) revealed loss of heterozygosity in two tumors: an osteosarcoma from a patient with retinoblastoma that had been included as a control, and one polyposis tumor that had been established in nude mice from a duodenal carcinoma biopsy. Loss of heterozygosity was observed in the first passage of the mouse tumor. Chromosome analysis in later passages revealed loss of one whole chromosome #13 as the single consistent karyotypic change.

Erroneous diagnosis of pancreatic cancer after radiotherapy of testicular cancer.

BACKGROUND: After radiotherapy with or without chemotherapy radiation-induced normal tissue alteration may mimic cancer and may cause major morbidity. RESULTS: Two patients irradiated for seminoma, in one case combined with cisplatin-based chemotherapy, developed clinical symptoms and radiological signs comparable to pancreatic cancer (stenosis of the ductus choledochus). The non-malignant diagnosis was finally established by revision of the histological specimen (case 1) and per-operatively (case 2). In both patients by-pass operations for biliary tract stenosis resulted in excellent palliation. CONCLUSION: Radiation-induced fibrosis within the upper retroperitoneal space is an important differential diagnosis versus pancreatic cancer in patients with prior radiotherapy for seminoma. Diagnosis based only on clinical and radiological findings may lead to incorrect patient information and registration errors in Cancer Registries.

Leiomyosarcoma (LMS) and endometrial stromal sarcoma (ESS) of the uterus. A survey of patients treated in the Norwegian Radium Hospital 1976-1985.

One hundred and twenty-seven patients with leiomyosarcoma (LSS) or endometrial stromal sarcoma (ESS) were treated at the Norwegian Radium Hospital during the 10-year period 1976-1985. After a review of the histologic slides 14 of the original tumors were reclassified, three as carcinomas and in 11 cases no malignant criteria were found. Five-year survival was 67% and 39% for ESS and LSS, respectively. Malignancy grade was the most powerful prognostic criterion in patients who were considered radically treated with surgery. Patients with grade 1 and 2 tumors had a prognosis similar to patients with endometrial carcinoma in contrast to the very gloomy outlook for patients with grade 3 and 4 (5-year survival 33%). For ESS the mitotic index also influenced the outcome. Despite widespread use of chemotherapy there is no clear indication that the prognosis for patients with the more aggressive types of sarcoma has improved in the period studied.

A mucinous carcinoma of the thyroid.

A primary mucinous carcinoma of the thyroid is reported. The tumour cells, arranged in small nests and trabecules, were surrounded by abundant intercellular substance which was positively stained for mucicarmine, alcian blue and PAS before and after diastase treatment. Diastase-resistant, PAS-positive material was also present in the tumour cells. Electron microscopy revealed neoplastic cells linked by desmosomes and not surrounded by basal lamina; the nuclei had irregular contours, prominent nucleoli and numerous pseudoinclusions; mucin granules and rough endoplasmic reticulum were the prominent organelles in the cytoplasm. Follicles and follicle-like structures were not found, either by light or by electron microscopy. A definite diagnosis could only be established after the disclosure of intense immunostaining for thyroglobulin in several groups of tumour cells. Criteria for the diagnosis are discussed and the question of histogenesis raised.

Genetic alterations in a malignant schwannoma from a patient with neurofibromatosis (NF1).

In a patient with neurofibromatosis (von Recklinghausen disease; NF1), normal lymphocytes, five cutaneous neurofibromas, and tumour tissue from a recurrence of a malignant schwannoma were analysed for genetic alterations. Eleven DNA markers located on chromosome 17 and nine randomly chosen markers representing chromosomes 1, 2, 3, 4, 5, 6, and 11, were analysed. High resolution Giemsa banding of lymphocytes revealed no chromosomal rearrangement. The DNA from the neurofibromas were all found to have the same restricted fragment length polymorphism pattern as the constitutional DNA from the patient. In the malignant schwannoma a complete loss of one allele was found at polymorphic loci on chromosome arm 17p. One gene copy of the TP53 gene (17p13.1) and the NF1 gene (17q11.2) was lost, as was one copy of the PGA gene (11q13). No mutations were detected in the mutational hotspots of the TP53 gene. Partial losses were detected at three loci on chromosomes 1, 2 and 6, indicating a clonal variation within the tumour since histological evaluation disclosed no normal tissue in the analysed specimen. Our data indicate that the NF1 gene may function as a tumour suppressor gene, and that, either by effect of dose reduction or complete inactivation, both the NF1 gene and the TP53 gene may be critical for the progression of a neurofibroma to a malignant schwannoma. The observations made are consistent with the concept of stepwise multigenetic changes in tumour progression.

Intracranial primary leiomyosarcoma arising in a teratoma of the pineal area.

The case of a 33-year-old man with a primary leiomyosarcoma arising in a mature teratoma in the pineal area is presented. The tumor extended into the posterior part of the third ventricle and caused hydrocephalus. Its smooth muscle derivation was confirmed by immunohistochemistry and electron microscopy. The patient has been followed for more than 2 years after surgery and postoperative radiotherapy. He has full working capacity and there are no signs of tumor recurrence. To our knowledge this is the first presentation of a leiomyosarcoma derived from a teratoma in the pineal area.