Mucinous adenocarcinoma of the colon - a histochemical study.

Colorectal carcinoma is a major cause of cancer associated with a high rate of morbidity and mortality in the western world. One of the pathologic features considered to be important for prognostic is mucin production. Many authors confirmed that colon carcinomas with high mucin content tend to re-occur locally and carry a poor prognosis. For histochemical evaluation of mucin content, we investigated 149 patients who underwent surgical resection of sporadic colon adenocarcinomas, all over a 5-year period. For histological classification we used the WHO recommendation (2000) and to be more accurate we sub-classified mucinous adenocarcinomas by morphometrical analysis in three categories: pure mucinous, with extracellular mucin more than 80% of the tumoral volume; mixed type, with 50-80% extracellular mucin; and mixed type with less than 50% extracellular mucin. For histochemical investigation, we used stains such as: mucicarmine, PAS ÷ Alcian Blue and High Iron Diamine ÷ Alcian Blue. Our study proved the predominance of mixed mucinous adenocarcinomas with less than 50% extracellular mucin, followed by the pure mucinous type. From the biochemical composition's point of view, the predominant cases were those with acidic mucins, especially in pure mucinous adenocarcinomas (>90%), while those with mixtures of acidic and neutral mucins were present in 62% of the cases. In addition, our study showed the prevalence of sialomucins over sulphomucins (68%), particularly in pure mucinous adenocarcinomas (77%). Clinical pure mucinous forms were detected mainly in advanced stages, but in terms of lymph node metastasis rate, they were secondary after mixed type with 50-80% extracellular mucin.