A 58-year-old Indian man presents with a 4-month history of progressive dyspepsia, early satiety, and unintentional weight loss of 8 kg. He has a 20-year history of chronic atrophic gastritis. On examination, he is pale and has a palpable left supraclavicular lymph node. Upper endoscopy reveals a large ulcerated lesion in the gastric antrum. Biopsy shows adenocarcinoma with signet-ring cells. CT staging shows no distant metastases but regional lymph node involvement. What is the most likely histological type and its association with this patient's gastric pathology?

Explanation

## Histological Classification and Pathogenesis ### Lauren Classification Gastric adenocarcinomas are classified into two main types: | Feature | Intestinal Type | Diffuse Type | |---------|-----------------|---------------| | **Histology** | Well-formed glands, cohesive cells | Signet-ring cells, scattered infiltration | | **Precursor** | Intestinal metaplasia → dysplasia | Chronic atrophic gastritis; no clear precursor | | **Growth pattern** | Localized, mass-forming | Infiltrative, diffuse | | **Prognosis** | Generally better | Worse, often advanced at diagnosis | | **Geographic association** | High in endemic areas | Hereditary (CDH1 mutations) | **Key Point:** The signet-ring cell morphology with scattered infiltration defines the diffuse type, which arises in the setting of chronic atrophic gastritis—exactly this patient's background. ### Pathogenic Sequence in This Case 1. **Chronic atrophic gastritis** (20-year history) → loss of normal gastric glands 2. **Intestinal metaplasia** → replacement of gastric mucosa with intestinal-type epithelium 3. **Dysplasia** → malignant transformation 4. **Diffuse-type adenocarcinoma** → signet-ring cells infiltrate the gastric wall **High-Yield:** Signet-ring cell carcinoma = diffuse type = poor prognosis = often presents at advanced stage with lymph node involvement (as in this patient's left supraclavicular node). ### Clinical Correlation **Clinical Pearl:** The presence of a palpable left supraclavicular lymph node (Virchow node) indicates metastatic spread and is a sign of advanced gastric cancer. The diffuse type is notorious for early lymphatic and peritoneal spread. **Warning:** Do NOT confuse diffuse-type gastric cancer with hereditary diffuse gastric cancer (HDGC), which is associated with CDH1 mutations and occurs in younger patients without a precursor lesion. This patient's cancer arose from chronic atrophic gastritis, making it sporadic diffuse-type cancer. ## Why Signet-Ring Cell Morphology Matters **Mnemonic: SRC = Scattered, Rare cohesion, Cytoplasm-filled** - Signet-ring cells have abundant intracytoplasmic mucin that displaces the nucleus to the periphery - They infiltrate individually through the gastric wall (linitis plastica pattern) - This explains the poor prognosis and advanced stage at presentation [cite:Robbins 10e Ch 17]