Anke Dam

High frequency of TP53 mutations in juvenile pilocytic astrocytomas indicates role of TP53 in the development of these tumors.

In adults, the TP53 tumor suppressor gene is frequently mutated in astrocytic brain tumors which is supposed to represent an early event in their development. In juvenile pilocytic and low‐grade astrocytomas, however, TP53 mutations have until now been reported as rare, which has led to the suggestion that these tumors may follow a different molecular pathogenesis with an involvement of genes other than TP53. Our analysis of 20 pilocytic and two lowgrade astrocytomas of childhood, based on a comprehensive denaturing gradient gel electrophoresis (DGGE) mutation detection assay of the entire coding region, including all splice site junctions of TP53, showed mutations considered as causative in 7 of the 20 (35%) pilocytic astrocytomas and in one of the two low‐grade astrocytomas. Our finding is significantly different from the mutation frequency of 1.3% (2/155) previously reported for these tumor types. This may be attributed to the mutation detection system used, which also detects mutations occurring outside the evolutionary conserved region of TP53. Our results suggest that, contrary to the present notion, TP53 mutations may well play a role in the development of juvenile astrocytomas. Furthermore, no mutations were found in tumors of patients with progression of residual tumor after postoperative follow‐up. This suggests that TP53 mutations may be associated with less aggressive forms of juvenile astrocytomas, analogous to the situation in adult astrocytomas.

Cytogenetics of thyroid follicular adenomas.

We present the results of a cytogenetic study of three cases of follicular adenoma of the thyroid. All three cases had a numerical strongly abnormal karyotype with most abnormalities (eg, +4 or +5, +7, +9, +12, +16) in common, possibly indicating that this cluster of abnormalities might be specific for follicular adenomas. For benign tumors, the three cases showed a remarkably abnormal karyotype. These cases are another example of benign tumors with chromosomal abnormalities that might be specific for follicular adenomas.

Cytogenetics as a tool in the histologic subclassification of chondrosarcomas

Chondrosarcomas are a heterogeneous group of bone neoplasms of which the basic neoplastic tissue is cartilaginous. Frequently the histologic diagnosis and grading of chondrosarcomas is difficult and the histologic appearance does not always reflect the biologic behavior of these tumors. Therefore, it is important to find other parameters that can be of help in the proper diagnosing and grading of these neoplasms. To this end, we attempted to correlate the chromosomal pattern of chondrosarcomas to their histologic subtypes and grades. The cytogenetic analysis of two intermediate-grade chondrosarcomas of bone, and a review of the literature, are presented.

An important role for chromosome 17, band q25, in the histogenesis of alveolar soft part sarcoma

A cytogenetic study of two cases of alveolar soft part sarcoma showed near-diploid karyotypes with multiple chromosomal rearrangements. An abnormality of the long arm of chromosome 17, involving band q25, is present in both cases and in 2 of 4 cases in the literature. This recurrent structural abnormality probably plays an important role in the histogenesis of this unusual neoplasm and therefore is important for further molecular investigation.

Genetics as a diagnostic tool in sarcomatoid renal-cell cancer.

Renal‐cell cancer comprises a heterogeneous group of tumors, which currently can be sub‐divided into morphologically distinct entities, each characterized by a specific combination of genetic changes. Sarcomatoid transformation might occur in any of the sub‐types, resulting in tumors consisting of both carcinomatous and sarcomatous components. The specific diagnosis of these neoplasms, as to tumor sub‐type, is usually made on the histologic properties of the carcinomatous tissue present. However, this might not reflect the true nature of the sarcomatous component. Since the genetic changes associated with the development of the different sub‐types of renal‐cell cancer are well established, this knowledge might serve as a tool in diagnosing sarcomatoid tumors. Assessing the genetic constitution of the latter may lead to correct diagnosis. It may also provide valuable information about the genetic changes associated with sarcomatoid transformation. Hence we performed a genetic characterization of a case of sarcomatoid renal‐cell cancer, histologically diagnosed as being of the chromophilic type. The observed genetic changes included loss of 3p, 6q, 8p, 9, 13, 14 and 17p, and gain of 5, 12 and 20, as well as a mutation in the coding region of the p53 gene. This combination of genetic changes points to clear‐cell rather than chromophilic origin of the sarcomatoid tumor investigated, indicating that the genetic constitution of sarcomatoid tumors may be a more reliable indicator of tumor sub‐type than histologic appearance. Int. J. Cancer 72:265–269, 1997.

Chromosomal aberrations in follicular thyroid carcinoma: Case report of a primary tumor and its metastasis☆

We present the result of a cytogenetic study of a case of follicular carcinoma of the thyroid and its metastasis. Both tumors have a low number of chromosomes. The primary tumor is characterized by a idic(22;22)(p11;p11). The skeletal metastasis has also structural abnormalities of chromosome 22.

Comparison of the chromosomal pattern of primary testicular nonseminomas and residual mature teratomas after chemotherapy

About 70 to 75% of patients with nonseminomatous testicular germ cell tumors (NSs) present with metastases. When these metastases are treated with chemotherapy, often residual mature teratoma (RMT) is left. RMT is composed of fully differentiated somatic tissue. Untreated metastases of NSs rarely consist exclusively of mature somatic tissue. Apparently, after chemotherapy treatment there is a shift towards higher degrees of differentiation. Investigating tumor progression and the mechanism(s) involved in therapy-related differentiation, we compared the cytogenetically abnormal karyotypes of a series of 70 NSs with those of 31 RMTs. In NSs and RMTs, the modal total chromosome number does not differ and is in the triploid range. Both the frequency and the average copy number of i(12p) are the same, and the pattern of chromosomal over- and underrepresentation and distribution of breakpoints do not differ significantly in these series. So, we found the chromosomal pattern of RMTs as abnormal as those of primary NSs. Based on cytogenetics, we found no indication that specific chromosomal alterations parallel metastasis and therapy-related differentiation of the metastases. The cytogenetic data suggest that both induction of differentiation of (selected) cells or selection of cells with capacity to differentiate are possible mechanisms for the therapy-related differentiation of RMTs.

Significance of aneuploid stemlines in testicular nonseminomatous germ cell tumors

Background. Hyperpentaploidy in testicular nonse‐minomatous germ cell tumors (TNSGCT) has been associated with progression of disease of patients who initially had TNSGCT in Stage I.

Clinical outcome of patients with previously untreated soft tissue sarcomas in relation to tumor grade, DNA ploidy and karyotype

The most important prognostic factor in soft tissue sarcomas (STS) is tumor grade. Since most grading methods are subject to the interpretation of the individual pathologist, there is a need for objective criteria such as DNA ploidy and karyotype, which are of prognostic value in several types of malignancy. We have analyzed the relationships among tumor grade, DNA ploidy, cytogenetic abnormalities and the clinical outcome of 44 previously untreated patients with 12 different histological types of primary STS. The tumors were graded according to the method of Coindre, which resulted in 9 grade I (20%), 18 grade II (41%) and 17 grade III (39%) STS. DNA flow cytometry and chromosomal analysis were performed using standard techniques. After a median follow‐up time of 39 (range, 2–124) months, Kaplan‐Meier survival analysis was performed. Significant differences in 5‐year overall survival were found between patients with grade I or II and grade III STS (p < 0.05). Seventeen STS were aneuploid and 26 were euploid. In 21 of 39 successfully cultured STS an abnormal karyotype was found. There were no significant differences in survival in relation to DNA ploidy or the presence of chromosomal abnormalities. Our results show that grading had higher prognostic value than DNA ploidy or the presence of cytogenetic abnormalities in this heterogeneous group of STS. Int. J. Cancer 74:396–402, 1997.

CYTOGENETIC STUDY OF A NODULAR HYPERPLASIA OF THE THYROID AFTER IRRADIATION FOR HODGKIN'S DISEASE

We describe cytogenetics of a case of nodular hyperplasia of the thyroid with papillary microcarcinoma following radiotherapy for Hodgkins disease. The chromosomal pattern found was very heterogeneous with a clonal abnormality of chromosome 10, among others. Together with some recent data from the literature, this finding may point to an important role of chromosome 10 abnormalities in the pathogenesis of benign and malignant thyroid neoplasms.