Nucleolar organiser regions as indicators of post-surgical prognosis in canine spontaneous mast cell tumours

Abstract

Summary The average number of nucleolar organiser regions per cell has previously been shown to correlate well with histological grading techniques for a variety of neoplasms in man, and may thus be of value as an aid to post-surgical prognosis. In this study 50 spontaneously arising, subcutaneous canine mast cell tumours were graded and the histological grade compared with the mean AgNOR count. For well differentiated neoplasms the mean count was 1.4 per cell compared with 6 Cutaneous mast cell tumours are the most common histologically confirmed skin neoplasms of dogs in many parts of the world (Bostock, 1986) and are usually amenable to surgical ablation when first presented. It has been shown that, for animals with no clinical evidence of residual tumour immediately following removal, behaviour is closely related to histological grade. Thus, well differentiated tumours carry a favourable prognosis and poorly differentiated lesions a very guarded prognosis (Bostock, 1973;Patnaik et al., 1984). Many tumours, however, fall into an intermediate category in which the prognosis is more difficult to predict, with estimates of tumour related deaths varying between 20 and 50% (Bostock, 1986). Furthermore, the grading of mast cell tumours, particularly those of intermediate differentiation, is somewhat subjective, and there is marked discrepancy in the proportions of the various grades between series from different authors (Table I).Nucleolar organiser regions are present in the nucleus of all cells, where they act as the sites for transcription of rRNA. They can be visualised readily in either impression smears or formalin fixed, routinely processed paraffin sections because of their close association with proteins containing a large number of disulphide bonds, which bind to silver ions . They are, therefore, usually referred to as AgNORs when stained in this way.Crocker and his colleagues have shown that the average number of AgNORs per nucleus correlates well with histological grading methods for a variety of human neoplasms, including lymphomas (Crocker & Nar, 1987), mammary tumours and melanomas (Crocker & Skilbeck, 1987) while others (Derenzini et al., 1988) have similarly demonstrated an increased number in intestinal adenocarcinomas compared with hyperplastic polyps.In view of these correlations we considered that the number of AgNORs might be of value as a prospective indicator of prognosis in canine mast cell tumours, particularly in view of their ease of demonstration and objectivity of measurement.In dogs, most mast cell tumours which are destined to kill their host do so within 6 months of initial excision as a result either of inoperable local recurrence in the scar, or lymphatic metastasis (Bostock, 1973) which follow-up studies in excess of 5 years are normally required. Materials and methodsSpontaneously arising subcutaneous mast cell tumours were excised by veterinary surgeons in general practice, fixed in formal saline and submitted for histological examination. Data supplied at the time of submis...

Mastocitoma cutâneo canino: estudo de 45 casos

“…As lâminas ficaram imersas nessa solução durante 45min em temperatura ambiente. Foram lavadas em água deionizada por 1min, desidratadas, clarificadas e montadas com resina sintética (Bostock et al, 1989;Simões et al, 1994;Kravis et al, 1996). Para definir a freqüência de AgNOR, foram contados os pontos pretos no interior dos núcleos em 100 mastócitos tumorais, em campos aleatórios e representativos de maior aumento (1000X).…”

“…Essa subjetividade é mais acentuada em mastocitomas de diferenciação intermediária (grau II). O prognóstico é mais difícil de predizer, e as mortes relatadas nesses animais variam entre 20 e 50% (Bostock et al, 1989). É descrito que uma proporção dos mastocitomas de grau II possui comportamento biológico de mastocitomas de grau I e outros, de mastocitomas de grau III (Séguin et al, 2001).…”

“…Estudos da técnica em neoplasias humanas mostram que o número de AgNOR por núcleo correlaciona com o grau histológico. Quanto maior o número de pontos argirofílicos intranucleares, pior é o prognóstico (Bostock et al, 1989).…”

E-cadherin in canine mast cell tumors: Decreased expression and altered subcellular localization in Grade 3 tumors

“…Clinical and molecular studies of MCTs have focused on precisely identifying the molecular alterations for each grade and defining the biochemical and biological impact on cancer cell proliferation and differentiation (Bostock et al, 1989;Simoes et al, 1994;Abadie et al, 1999;Leibman et al, 2000;Lana et al, 2000;Bergmann, 2003;Scase et al, 2006;Wu et al, 2004;Webster et al, 2007;Strefezzi et al, 2009). The expression profiles of a variety of biological markers, such as Ki67, c-Kit, Ag-NOR, chymase and tryptase, have been investigated as potential prognostic markers (e.g.…”

“…The expression profiles of a variety of biological markers, such as Ki67, c-Kit, Ag-NOR, chymase and tryptase, have been investigated as potential prognostic markers (e.g. progression, metastasis and life expectancy) (Bostock et al, 1989;Simoes et al, 1994;Abadie et al, 1999;Bergmann, 2003;Scase et al, 2006;Wu et al, 2004;Webster et al, 2007).…”