ABSTRACT
OBJECTIVE: Chronic infection with Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis) has been proposed as a cause of Crohn's disease. Although numerous investigators have examined the link between M. paratuberculosis and Crohn's disease, the evidence remains controversial. The aim of this study was to examine intestinal granuloma from Crohn's patients for M. paratuberculosis using a semi-nested M. paratuberculosis-specific IS900 polymerase chain reaction (PCR). MATERIAL AND METHODS: Paraffin-embedded ileal or colonic tissues of patients with Crohn's disease were analyzed. Microdissection of this tissue into "granulomas" and "not granulomas" was performed. On the basis of sequences reported in GenBank alignments, we designed primer sets specific for M. paratuberculosis. The presence of the M. paratuberculosis was examined by semi-nested IS900-specific PCR with human beta-actin gene as a control for DNA quality. RESULTS: Biopsies from 20 Crohn's patients were examined. Human beta-actin gene was amplified in all samples. M. paratuberculosis DNA was detected in the microdissected granuloma in 1 (5%) patient with Crohn's disease and in none of the "not granuloma" tissues. CONCLUSIONS: M. paratuberculosis DNA can rarely be detected within Crohn's granuloma. These results do not support M. paratuberculosis as the primary etiology of Crohn's disease.
Subject(s)
Crohn Disease/microbiology , DNA, Bacterial/analysis , Granuloma/microbiology , Mycobacterium avium subsp. paratuberculosis/isolation & purification , Paratuberculosis/diagnosis , Adult , Base Sequence , Crohn Disease/pathology , Female , Granuloma/pathology , Humans , Intestinal Mucosa/microbiology , Intestinal Mucosa/pathology , Male , Middle Aged , Molecular Sequence Data , Paraffin Embedding , Polymerase Chain Reaction , Probability , Reference Values , Retrospective Studies , Sensitivity and SpecificityABSTRACT
The development of adenocarcinoma or carcinoid tumors in atrophic gastritis is widely documented. We report the simultaneous occurrence of gastric adenocarcinoma and carcinoid (composite tumor) in atrophic gastritis, a finding reported only twice before in the literature. This 52-yr-old man with rectal bleeding, epigastric pain, and iron deficiency anemia was noted to have multiple polypoid masses on upper endoscopy. Biopsy revealed features of both adenocarcinoma and carcinoid tumor in a background of atrophic gastritis, leading to a total gastrectomy, lymph node dissection, and liver biopsy. The gastrectomy specimen was characterized by a 6 cm pedunculated polyp and multiple sessile nodular masses between 0.4 and 2.5 cm in the background of a granular mucosa. On microscopic examination, the large polypoid mass corresponded to a well-differentiated adenocarcinoma, intestinal type, infiltrating the wall. The smaller nodules were composed of carcinoid tumors, restricted to the mucosa, or infiltrating the gastric wall. Carcinoid tumor was also seen in the large polypoid mass closely intermingled with adenocarcinoma. The carcinoid tumor metastasized to the liver. Lymph nodes showed both adenocarcinoma and carcinoid tumor. The gastric mucosa was characterized by atrophic gastritis with intestinal metaplasia, neuroendocrine hyperplasia, and microcarcinoids. The adenocarcinoma stained strongly for CK7, CK 20, MIB-1, and focally for chromogranin and synaptophysin. The carcinoid tumor was negative for CK7, CK 20 and MIB-1, and was positive for chromogranin and synaptophysin. Overexpression of p53 was noted only in the adenocarcinoma. Electron microscopy revealed neurosecretory granules in the carcinoid characteristic of a neuroendocrine tumor. Composite tumor can occur in the setting of atrophic gastritis. The findings in this patient reinforce the concept that the epithelial and neuroendocrine cells of the gastrointestinal tract both result from multidirectional differentiation of a primitive cell.
