A 58-year-old man from rural India presents with progressive dysphagia and epigastric pain for 4 months. He reports early satiety and unintentional weight loss of 8 kg. On examination, he appears cachectic. Upper endoscopy reveals a large, ulcerated lesion in the antrum with rolled edges and surrounding erythema. Biopsy shows adenocarcinoma with signet-ring cells. CT abdomen shows thickening of the gastric wall with involvement of regional lymph nodes but no distant metastases. Which histological subtype carries the worst prognosis in this patient?

Explanation

## Histological Classification of Gastric Carcinoma **Key Point:** The Lauren classification divides gastric adenocarcinoma into intestinal and diffuse types, with diffuse type (including signet-ring cell carcinoma) having significantly worse prognosis. ### Comparison of Histological Subtypes | Feature | Intestinal Type | Diffuse Type (Signet-Ring) | Mucinous | Neuroendocrine | |---------|-----------------|----------------------------|----------|----------------| | **Location** | Distal/antrum | Throughout stomach | Antrum/body | Variable | | **Precursor** | Intestinal metaplasia | No clear precursor | Mucous glands | Neuroendocrine cells | | **Prognosis** | Better (Stage I: ~60% 5-yr survival) | Worse (Stage I: ~30% 5-yr survival) | Intermediate | Variable | | **Growth pattern** | Infiltrative with ulceration | Diffuse infiltration, linitis plastica | Mucin pools | Nested/trabecular | | **Signet-ring cells** | Absent/rare | Present (defining feature) | Absent | Absent | | **Metastasis** | Regional lymph nodes early | Peritoneal, hematogenous | Peritoneal | Lymph nodes | **High-Yield:** Signet-ring cell carcinoma (diffuse type) is characterized by: - Individual cells with eccentric nuclei pushed to periphery by mucin - Diffuse infiltration of gastric wall (linitis plastica when extensive) - Higher propensity for peritoneal seeding and ascites - Earlier presentation at advanced stages - 5-year survival ~20% vs. ~40% for intestinal type **Clinical Pearl:** The patient's presentation with early satiety and weight loss suggests advanced disease; signet-ring cell carcinoma frequently presents this way because it infiltrates diffusely without forming a discrete mass, making early detection difficult. ### Why Diffuse Type Has Worse Prognosis 1. **Diffuse infiltration** — Spreads through submucosa and muscularis propria without forming a localized mass 2. **Peritoneal involvement** — Higher rate of peritoneal carcinomatosis and ascites 3. **Advanced stage at diagnosis** — Often T3/T4 at presentation due to lack of early warning signs 4. **CDH1 mutations** — Associated with hereditary diffuse gastric cancer (HDGC); aggressive biology **Mnemonic:** **SIGNET** = **S**pread diffusely, **I**nfiltrative growth, **G**ene CDH1 mutations, **N**o localized mass, **E**arly peritoneal seeding, **T**errible prognosis [cite:Robbins 10e Ch 17]