[Biopsies of kidney lesions: when and how?] / Biopsien von Nierenläsionen: wann und wie?

The demand for image-guided renal biopsy has increased due to the better detection of renal lesions; however, despite modern imaging techniques many small renal tumors cannot be classified as benign because they cannot be differentiated from renal cell carcinoma. Ultrasound and computed tomography (CT)-guided kidney biopsy is a safe and accurate method in the diagnostics of renal lesions and can be helpful in the selection of new ablative and pharmaceutical forms of treatment and avoid unnecessary operations. This article describes the clinical indications for an image-guided biopsy and discusses factors which should be considered when performing a biopsy.

Cytogenetic analysis of three oropharyngeal malignant melanomas in dogs.

Three cases of histologically confirmed oropharyngeal malignant melanomas in dogs are presented including clinical examinations and cytogenetic analysis. Case one showed a hyperdiploid karyotype. Case two, a recurrent tumour, had a highly hypodiploid karyotype with supernumerary meta- and submetacentric chromosomes in all metaphases analysed. In the third case, a clonal fusion of chromosome 1 and 25 was observed. Comparing these results with another case of canine cutaneous melanoma as well as with human malignant melanomas reported in the literature, these tumours obviously often show cytogenetic aberrations like aneuploidy and centric fusions.

Cytogenetic investigation of canine lipomas.

Akin to humans, lipomas are common in the dog as well; however, until now there were no reports of cytogenetic investigations on these tumors in the canine. We report our results of cytogenetic investigations on a series of ten canine lipomas. Clonal aberrations were observed in seven cases. In one case a trisomy 27 was evident; in another case a trisomy 13 was present in addition to a marker chromosome. A third lipoma showed a fusion of chromosomes 2 and 13. These cases showed one derivative chromosome each (der(X), der(7), and der(4)), and one case had two derivative chromosomes (der(X) plus der(4)). In the two cases with derivative chromosomes 4, the same region (4q31) was affected. It is tempting to speculate that this region might harbor a gene associated with tumor development. The results are compared to the cytogenetic situation in human lipomas.

Working with canine chromosomes: current recommendations for karyotype description.

There is an increasing interest in genomic research on the domestic dog (Canis familiaris). However, these investigations are complicated by the canine karyotype comprising 76 acrocentric autosomes of similar size and shape and the metacentric sex chromosomes. None of the numerous published ideograms and karyotypes has yet been generally accepted. The present article gives a review of these descriptions of the canine karyotype. The two most recent nomenclatures and the current efforts toward a standardized canine karyotype made by the Committee for the Standardized Karyotype of the Dog are discussed in detail and recommendations for future use of a nomenclature for the canine karyotype are given.

[Oropharyngeal tumors of dogs--a clinical study of 79 cases]. / Oropharyngeale Tumoren des Hundes--Eine klinische Studie über 79 Fälle.

This study presents the data on incidence, TNM-classification and therapy outcome of 79 dogs with oropharyngeal tumors, which were admitted to the Clinic of Small Animals, Hannover School of Veterinary Medicine. 52 neoplasms were examined histologically. The most common tumors were malignant melanoma (n = 17), fibrosarcoma (n = 5), squamous cell carcinoma and peripheral odontogenic fibroma (n = 4). It could be determined that dogs treated by surgery, regardless of tumor type and type of surgery, had longer survival times than untreated dogs. With regard to survival time and the rate of local tumor recurrence, radical surgery (partial mandibulectomy/maxillectomy) led to good results in squamous cell carcinomas and invasive odontogenic tumors, but, keeping in mind the small number of cases, showed no advantage over conservative surgery in malignant melanomas, fibrosarcomas, neurofibrosarcomas and non invasive odontogenic tumors. It could be shown that the clinical staging of the patients was of prognostic relevance.

Trisomy 1 in a canine acute leukemia indicating the pathogenetic importance of polysomy 1 in leukemias of the dog.

We report on a canine acute myeloid leukemia showing a trisomy 1 and a t(X;8) as clonal cytogenetic abnormalities. Comparing these results with similar cases of canine leukemias reported in the literature, one realizes that trisomy 1 is a recurrent cytogenetic finding in canine acute leukemia. Trisomy 1 may be a specific anomaly associated with either etiology or progression of this disease. As with comparable human neoplasms, cytogenetic investigations could be of diagnostic and prognostic significance for canine hematopoietic diseases. Moreover, as trisomies are recurrent cytogenetic findings in human leukemias, as well, comparative gene mapping in future studies may help to focus the etiologic basis of the disease to particular chromosomal segments instead of whole chromosomes.

[Importance of cytogenetic investigations in canine leukemias]. / Die Bedeutung zytogenetischer Untersuchungen bei Leukämien des Hundes.

Like in man, in neoplastic haematopoietic diseases of the dog genetical changes can be detected cytogenetically. In this study, some cytogenetically characterized cases are presented and discussed against the background of comparable cases reported in the literature. In two out of three patients investigated, one or two extra copies of chromosome 1 were detected. Corresponding changes have also been described in two other cases in the literature.

Trisomy 18 in a canine thyroid adenoma.

A canine thyroid adenoma showing trisomy 18 as the sole clonal cytogenetic abnormality (9 of 30 analyzed metaphases) is reported. Because trisomies are a recurrent cytogenetic finding in human benign thyroid tumors as well, it is suggested that the molecular relationship between these trisomies and the development of thyroid tumors can be determined by comparative gene mapping.

Report on the progress of standardization of the G-banded canine (Canis familiaris) karyotype. Committee for the Standardized Karyotype of the Dog (Canis familiaris).

Karyotyping of dog chromosomes is a difficult task owing to the high diploid number of chromosomes (2n = 78) and the similar morphology of autosomes, all of which are acrocentrics. In this report 22 of the 39 G-banded chromosome pairs and their corresponding ideograms have been standardized. The ideogram comprises altogether 235 bands. The need for the introduction of molecular techniques such as chromosome painting and physical mapping of genetic markers for the identification of small acrocentrics is discussed.

An extended nomenclature of the canine karyotype.

In contrast to many other animals, knowledge about the canine karyotype is quite sparse. This is due in part to the rather difficult canine karyotypic pattern. Except for the X and the Y chromosome, there are only acrocentric chromosomes, which appear to be quite small and difficult to identify unambiguously. In previous reports, schematic representations of the canine karyotype have been described. However, a nomenclature comparable to that of the human karyotype or the karyotypes of sheep, cattle, or goats does not yet exist for the dog. Based on high-resolution banding of metaphase chromosomes from canine fibroblasts, we propose an ideogram of the canine karyotype with 460 numbered bands and characteristic landmarks. In addition, the centromere positions of the canine chromosomes are determined by a combined GTG-banding/FISH approach, and the R- and G-banding patterns are compared.

Evidence that metacentric and submetacentric chromosomes in canine tumors can result from telomeric fusions.

We have hypothesized that metacentric and submetacentric chromosomes frequently observed in malignant canine tumors are a result of telomeric fusions. Therefore cells from a canine mammary pleomorphic adenoma were transformed with a plasmid containing the SV40 'early region', known to cause telomeric associations. Compared with non-transformed adenoma cells, the cells had a higher proliferative capacity and expressed the large SV40-T-antigen. Karyotype studies showed the conversion from a normal to an aberrant karyotype with an increase of bi-armed chromosomes resulting from fusions of acrocentric chromosomes. In addition, the length of the telomeric repeats (TTAGGG) was determined for an early and a late passage of the transformed cells by Southern hybridization. The length of the telomeric repeats was apparently longer in the 5th than in the 38th passage. In situ hybridization with a telomere-specific DNA revealed interstitial telomeric repeats in the bi-armed chromosomes. We have concluded that these findings reflect the clonal expansion of head-to-head-telomeric fusions of canine acrocentric chromosomes leading to dicentric chromosomes with a very short distance between the two centromeres. Our results support the idea that the apparent centric fusions that have been described in some canine tumors may in fact be the cytogenetic products of head-to-head-telomeric fusions.