Benign and malignant tumours of the uterine body
Which cells of the uterine body give rise to which tumours, how unopposed oestrogen or an early TP53 mutation leads to endometrial carcinoma, how it invades and spreads, and why bleeding is so often its first sign.
By the end, you can
- Relate the endometrial glands, endometrial stroma and myometrium to the benign and malignant tumours each gives rise to.
- Explain how unopposed oestrogen drives the pathway from hyperplasia to endometrioid carcinoma.
- Contrast endometrioid and serous carcinoma, and describe the four molecular groups of endometrial carcinoma.
- Describe how endometrial carcinoma invades and spreads, and what grade and stage measure.
- Distinguish leiomyosarcoma from leiomyoma and explain why abnormal bleeding is an early sign of endometrial carcinoma.
What it is
Tumours of the uterine body (corpus) arise from its three tissues: the glandular epithelium of the endometrium, the endometrial stroma, and the smooth muscle of the myometrium. The commonest benign growths are leiomyomas (fibroids) and endometrial polyps. The commonest malignant tumour is endometrial carcinoma, a cancer of the glandular epithelium; uterine sarcomas (from muscle or stroma) are rare.
5 types to tell apart
- Endometrial polyp
- A benign, localised overgrowth of endometrial glands and stroma around thick-walled vessels, projecting into the cavity; it can bleed, and occasionally harbours hyperplasia or carcinoma.
- Endometrioid carcinoma
- The commonest type: glands resembling proliferative endometrium, usually arising from atypical hyperplasia in an oestrogen-rich setting; most are low grade and found early.
- Serous and clear cell carcinoma
- High-grade carcinomas, usually in older women with a thin (atrophic) endometrium; serous carcinoma carries an early TP53 mutation and can spread across the peritoneum early.
- Carcinosarcoma
- An aggressive tumour with both malignant epithelium and malignant mesenchymal tissue; formerly called malignant mixed Müllerian tumour, it is now classed as a carcinoma whose cells have taken on a sarcoma-like form.
- Uterine sarcomas
- Rare malignant tumours of the myometrium (leiomyosarcoma) or endometrial stroma (endometrial stromal sarcoma, low or high grade), and adenosarcoma, with benign glands in a malignant stroma.
US spelling: tumours → tumors, tumour → tumor, oestrogen → estrogen, behaviour → behavior.
Normal function
Endometrium and myometrium
The and of the uterus have a thick wall of smooth muscle, the myometrium, lined by the endometrium: tubular glands of simple columnar epithelium set in a cellular stroma. The lower basal layer stays through each cycle; the upper functional layer grows and is shed at each period, then rebuilt from the basal layer.
Two ovarian hormones control the lining. Oestrogen, in the first half of the cycle, makes glands and stroma proliferate. After ovulation, progesterone stops this proliferation and turns the lining into a secretory, differentiated tissue ready for implantation. When progesterone falls, the functional layer is shed through the .
Each tissue can give rise to its own tumours, benign or malignant, and their behaviour follows the cell they came from.
| Feature | Benign | Malignant |
|---|---|---|
| Endometrial glands | Polyp (with stroma); hyperplasia is a non-neoplastic precursor setting | Endometrioid, serous and clear cell carcinoma |
| Endometrial stroma | Endometrial stromal nodule | Endometrial stromal sarcoma, low or high grade |
| Myometrial smooth muscle | Leiomyoma (fibroid) | Leiomyosarcoma |
| Glands and stroma together | Polyp; adenomyoma | Adenosarcoma (malignant stroma); carcinosarcoma (both malignant) |
Simplified from the WHO classification. Carcinosarcoma is classed with the carcinomas because its sarcoma-like part derives from the carcinoma.
Underlying change · Step 1 of 5
Unopposed oestrogen: the endometrioid route
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
Serous carcinoma and the molecular groups
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
Invasion and spread
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 5
Sarcomas of muscle and stroma
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
Why bleeding comes early
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 8 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .