[Early carcinomas of the upper gastrointestinal tract: diagnostic problems].

Problems arising when diagnosing biopsy material from the upper gastrointestinal tract are encountered in particular with changes that might minic a carcinoma. In the squamous epithelium of the oesophagus, such problem lesions are viral infections, regenerative changes in reflux disease, and pseudoepitheliomatous hyperplasia in subepithelial lesion. In Barrett's mucosa, regenerative changes are often overdiagnosed as low grade dysplasia, and will-differentiated adenocarcinomas underdiagnosed as high grade dysplasia. In the stomach, the regenerative mucosa at the margins of erosions and ulcers--in particular in the case of NSAID/ASA-induced lesions--is the most common cause of the wrong diagnosis of carcinoma. Such misdiagnoses can usually be avoided by taking careful account of the endoscopic findings. In the case of doubt, a second pathological opinion, an extensive endoscopy/biopsy follow-up examination (after treatment), or a diagnostic endoscopic mucosectomy, is to be recommended.