A 62-year-old woman is diagnosed with endometrial carcinoma on hysterectomy specimen. Histopathology shows Grade 2 endometrioid adenocarcinoma invading the inner half of the myometrium. Which is the most common site of metastasis in endometrial carcinoma?

Explanation

## Metastatic Pattern in Endometrial Carcinoma **Key Point:** Pelvic and para-aortic lymph nodes are the most common sites of metastasis in endometrial carcinoma, reflecting the anatomical lymphatic drainage of the uterus. ### Lymphatic Drainage of the Uterus 1. **Primary drainage:** Pelvic lymph nodes (internal iliac, external iliac, obturator) 2. **Secondary drainage:** Para-aortic (lumbar) lymph nodes via the ovarian vessels 3. **Tertiary spread:** Distant organs (lungs, liver, bone) ### Frequency of Metastatic Sites in Endometrial Carcinoma | Site | Frequency | Pathway | Clinical Significance | | --- | --- | --- | --- | | **Pelvic lymph nodes** | **40–60%** | **Lymphatic (primary)** | **Most common; staging critical** | | **Para-aortic lymph nodes** | **10–20%** | **Lymphatic (secondary)** | **Indicates advanced disease** | | Lungs | 5–10% | Hematogenous | Late finding | | Liver | 2–5% | Hematogenous | Late finding | | Bone | 1–3% | Hematogenous | Rare | | Peritoneum | 5–10% | Direct/transcoelomic | Variable stage | **High-Yield:** Lymph node metastasis is the most important prognostic factor after grade and myometrial invasion. **Pelvic lymphadenectomy** is a standard part of surgical staging for endometrial carcinoma. ### Why Lymph Nodes Are the Most Common Site - Endometrial carcinoma spreads first via **lymphatic channels** before hematogenous dissemination - The uterus has rich lymphatic drainage to pelvic and para-aortic nodes - Lymph node involvement occurs in ~15–20% of apparent Stage I disease (occult metastasis) - Distant organ metastases (lungs, liver, bone) occur late and are less frequent **Clinical Pearl:** A patient with Grade 2 endometrioid carcinoma with inner myometrial invasion is at intermediate risk for lymph node metastasis. Staging should include pelvic and para-aortic lymphadenectomy or imaging to assess nodal status. **Mnemonic:** **PLB** — **P**elvic nodes → **L**ungs → **B**one (order of frequency in endometrial cancer spread).