## Histological Classification of Gastric Carcinoma **Key Point:** The Lauren classification divides gastric carcinoma into two main types with distinct clinicopathological features and prognoses. ### Diffuse Type (Signet-Ring Cell Carcinoma) - Characterized by infiltrative growth of individual cells or small clusters - Signet-ring cells: mucin-filled cells with eccentrically placed nuclei - **Poorest prognosis** — early invasion of muscularis propria and beyond - Often presents at advanced stage (Stage III–IV) - Associated with CDH1 gene mutations (hereditary diffuse gastric cancer) - Rapid progression, high mortality ### Intestinal Type (Tubular/Papillary Adenocarcinoma) - Forms cohesive glandular structures - Better prognosis than diffuse type when matched for stage - Associated with intestinal metaplasia, chronic gastritis, H. pylori - More common in older patients, endemic areas - Slower growth, better response to surgery ### Comparison Table | Feature | Diffuse Type | Intestinal Type | | --- | --- | --- | | **Growth pattern** | Infiltrative, scattered cells | Cohesive glands | | **Cell morphology** | Signet-ring cells | Tubular/papillary | | **Prognosis** | Poor (5-year survival ~20%) | Better (5-year survival ~40%) | | **Stage at diagnosis** | Advanced (III–IV) | Often earlier | | **Genetic association** | CDH1 mutations | TP53, APC alterations | | **Risk factors** | Family history, hereditary | H. pylori, intestinal metaplasia | **High-Yield:** Signet-ring cell carcinoma is the hallmark of diffuse type gastric cancer and carries the worst prognosis due to its propensity for early transmural invasion and peritoneal seeding. **Clinical Pearl:** Hereditary diffuse gastric cancer (HDGC) syndrome with CDH1 mutations presents with diffuse signet-ring cell carcinoma and warrants prophylactic total gastrectomy in carriers. [cite:Robbins 10e Ch 17]
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