Tumores del Tracto Gastrointestinal

Gastrointestinal Tract Tumors

• Tumours of the gastrointestinal tract are a significant health concern.
• The oesophagus is a critical part of the digestive system, playing a vital role in transferring food from the mouth to the stomach.
• Oesophageal tumours, specifically adenocarcinoma, often originate as a result of Barrett's oesophagus.
• Increased rates of oesophageal adenocarcinoma correlate with rising incidence of obesity-related gastroesophageal reflux disease and Barrett's oesophagus.
• Other risk factors include tobacco use and radiation exposure.
• The majority of oesophageal adenocarcinomas occur in the distal third of the oesophagus, frequently presenting near the junction with the gastric cardia.
• These tumors frequently feature glands and exhibit an intestinal-type morphology in microscopic examinations.
• A lesser occurrence of infiltrative signet ring cell tumors exists in some patients.
• Esophageal squamous cell carcinomas commonly affect the upper and middle esophagus parts, primarily linked to smoking and alcohol usage.
• Various other risk factors may influence the development of esophageal cancer, encompassing poverty, caustic injury or other injuries, achalasia, poor diet, and Plummer Vinson syndrome.
• Risk factors for esophageal cancer should be identified to implement targeted preventative measures.

Stomach: Anatomy and Histology

• The stomach is a hollow organ involved in the initial stages of digestion.
• Its anatomy comprises the cardia, fundus, body, and pylorus, each with a specific role.
• The stomach's histology reveals distinct layers: mucosa, submucosa, muscularis externa, and serosa.
• The mucosa, containing gastric glands, is essential for secretion and absorption.
• The stomach's muscular layers facilitate churning and mixing of food.

Gastric Polyps

• Gastric polyps are growths in the stomach lining.
• Hyperplastic/inflammatory polyps typically arise in association with chronic gastritis.
• These growths are usually small and numerous, exhibiting an ovoid shape and smooth surface.
• Microscopically, foveolar glands in these polyps are frequently dilated and elongated while the lamina propria typically shows inflammation and possible surface ulceration.
• Individuals with H. pylori gastritis may experience polyp regression after eradicating the bacteria.

Fundic Gland Polyps

• Fundic gland polyps commonly arise in the stomach's fundus and body regions.
• These lesions tend to exhibit a smooth surface and can be singular or multiple.
• Microscopically, fundic gland polyps typically display irregular, dilated glands lined with flattened parietal and chief cells.
• The development of these polyps is frequently linked to proton pump inhibitor treatment, which can alter stomach acid production.
• Fundic gland polyps are typically not a cause for concern.

Gastric Adenoma

• Gastric adenomas are precancerous lesions that frequently develop within the stomach's antrum.
• They typically are solitary and less than 2 cm in size.
• The risk for adenocarcinoma formation increases with larger lesion size, especially above 2cm in diameter.
• High-grade dysplasia can be considered a more serious variant of gastric adenoma exhibiting significant cytological atypia and irregularities in glandular structure.

Gastric Adenocarcinoma

• Adenocarcinoma is the prevailing stomach cancer type.
• This arises frequently from a precursor lesion.
• Early symptoms are often nonspecific (e.g., indigestion, nausea).
• Advanced stages may show weight loss, anorexia, or bleeding.
• Common metastatic sites include the sentinel lymph node and other organs.
• Appropriate diagnostic procedures and management strategies are critical for minimizing complications and improving outcomes.

Gastric Lymphomas- MALT

• A significant cause of stomach lymphomas is chronic gastritis, which often results from $H. pylori infection.
• Commonly located in the mucosa associated lymphoid tissue of the stomach.
• Lymphomas frequently display a dense lymphocytic infiltration of the lamina propria, where the neoplastic lymphocytes display infiltration into the gastric glands.
• MALTomas are categorized as low-grade lymphomas and can potentially evolve into aggressive diffuse large B-cell lymphomas.
• They can be identified by specific markers like B-cell markers such as CD19 and CD20 and CD43.

Gastrointestinal Stromal Tumor (GIST)

• Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors frequently originating in the stomach (more than half), and less commonly in the distal colon and rectum;
• They're characterized by a significant portion (75-80%) harboring oncogenic mutations in the receptor tyrosine kinase KIT.
• Primary gastric GISTs can attain considerable size (up to 30 cm).
• GISTs are typically solitary and encased within the stomach lining.
• Microscopic examination shows a notable diversity in the morphological patterns of GISTs, including spindle-cell type, epithelioid type, and mixed types.
• Diagnosis relies on immunohistochemical staining using markers like CKIT/CD117.

Colon Anatomy

• The human colon is a crucial component of the digestive system.
• It comprises several distinct sections, chief among them being the ascending colon, transverse colon, descending colon, and sigmoid colon.

Colon Histology

• Colon histology reveals distinct layers, including mucosa, submucosa, and muscularis propria.
• Crypts are observed within the mucosal layer.

Colon Polyps (Hyperplastic, Sessile Serrated, and Tubular Adenomas)

• Hyperplastic polyps are common, benign, non-neoplastic growths that are frequently multiple.
• Sessile serrated adenomas (SSAs) are typically found in the right colon, displaying serrated architecture.
• Tubular adenomas are more commonly found in the left side, characterized by packed tubular crypts.
• All three subtypes have the potential to transform into cancerous lesions, emphasizing the importance of regular screening.

Adenomas—Epithelial Dysplasia

• Low-grade dysplasia is a precursor to high-grade dysplasia, which, in turn, can lead to carcinoma.
• Intramucosal carcinoma, where cancerous cells have invaded the lamina propria, arises from epithelial dysplasia.

Colorectal Cancer Progression, including Molecular Defects

• Progression of colon polyps (adenomas) to cancer involves a molecular pathway involving mutations in important genes such as APC, KRAS, TP53, SMAD2 and 4, and MSH2 or MLH1.

Familial Adenomatous Polyposis (FAP)

• A genetic predisposition often resulting in profuse, early-onset adenomatous polyps in the colorectal region.

Hereditary Non-Polyposis Colorectal Cancer (HNPCC)

• A genetic susceptibility to colon cancer not associated with having numerous adenomas.
• Caused by mutations in mismatch repair genes, like MLH1 and MSH2, which have implications for genetic counseling and increased risk of second primary tumors.

Appendiceal Tumors

• Well-differentiated neuroendocrine tumors are the most frequent appendix tumors.
• Appendix tumors are generally believed to be benign.
• Mucoceles (dilated appendices) can result from obstruction.