RESUMO

The purpose is to present the studies of RET gene expression and acetylcholinesterase activity in 23 patients operated for Hirschsprung's disease (HD). The patients underwent either transanal endorectal pull-through or Duhamell's procedure. Full-thickness intestinal samples from the three different segments (ganglionic, intermediate and aganglionic) were collected. Each tissue sample was divided in two portions, one for AChE histochemical staining and the other for examination of RET mRNA expression level. All patients had an uneventful postoperative recovery. In all patients, the AChE stainings demonstrated the absence of activity in the ganglionic area, the marked increase of positive fibers in the aganglionic area, and little increase of positive fibers in the intermediate area. In the ganglionic and intermediate areas, all patients (100%) showed significant RET gene expression. In the aganglionic area, 18 patients (78.3%) did not present gene expression and the other five patients (21.7%) presented gene expression that was similar to the ganglionic and intermediate areas. The results reinforce the conclusion that the method of AChE staining is effective for the diagnosis of intestinal aganglionosis and confirm the knowledge that genes beyond RET may be implicated in the genesis of sporadic cases of HD.

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RESUMO

Suction rectal biopsy with acetylcholinesterase (AChE) histochemistry has been recognized as a reliable method for the diagnosis of Hirschsprung's disease (HD). This study compares the final pathologic diagnosis made on paraffin embedded material of 68 colectomy specimens with the histochemical AChE reaction from the same patients previously diagnosed as HD by rectal suction biopsy at the Hospital Infantil Pequeno Príncipe (Curitiba, Brazil) from 1988 to 1999. The group included 58 male and ten female patients with ages ranging from 7 days to 10 years. Thirty-six patients (52.94 percent) where under 1 year of age at time of surgery. Two of the 68 patients had previous normal histochemical reactions for AChE: one of them resulted a normal ganglionic segment of bowel and the other one was a 15-day-old boy with total colonic aganglionosis, the only false-negative result in this series. Two patients had inconclusive results and because untreatable clinical symptoms also received surgical treatment. One of them resulted a normal ganglionic bowel and the other one was diagnosed as HD. All surgical specimens from the other 64 patients resulted in various extents of aganglionosis presenting prominent nerve trunks in the submucosal and myenteric plexuses, confirming the previous AChE histochemical diagnosis. In three cases there was total colonic aganglionosis. In this study the rectal suction biopsy associated with the histochemical method of AChE, performed days, months or sometimes years before surgery, resulted in a diagnostic accuracy rate of 95.59 percent, a positive predictive value of 100 percent and there were no false-positive results.

A biópsia de reto por sucção associada à histoquímica enzimática pela acetilcolinesterase (AChE) tem sido reconhecida como um método confiável para o diagnóstico da doença de Hirshsprung (HD). Este estudo compara o diagnóstico patológico final de 68 peças de colectomias incluídas em parafina com o diagnóstico prévio de HD através da reação histoquímica da AChE em biópsia por sucção retal dos mesmos pacientes, todos operados no Hospital Infantil Pequeno Príncipe, de Curitiba, entre 1988 e 1999. No grupo há 58 pacientes masculinos e dez femininos com idades variando entre 7 dias e 1 ano, sendo que 33 pacientes (52,94 por cento) tinham menos de 1 ano de idade no momento da cirurgia. Dos 68 pacientes, dois tiveram reação prévia normal pela AChE, porém, como persistiam com quadro de suboclusão intestinal, foram levados à cirurgia; um deles resultou HD, padrão aganglionose total do cólon, o único caso falso-negativo deste estudo. Outros dois pacientes tiveram resultado inconclusivo pela AChE, e um deles resultou HD no exame da colectomia. Todas as colectomias dos demais 64 pacientes resultaram agangliônicas (HD), apresentando proeminência de troncos nervosos nos plexos submucoso e mioentérico, confirmando o diagnóstico histoquímico prévio pela AChE. Em três casos havia aganglionose colônica total. Neste estudo a biópsia retal por sucção associada ao método histoquímico da AChE, realizado dias, meses ou anos antes da cirurgia, apresentou taxa de acurácia diagnóstica de 95,59 por cento, valor preditivo positivo de 100 por cento e nenhum resultado falso-positivo.

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