Benign epithelial tumours
How benign tumours of surface epithelium (papillomas) and of glands (adenomas) arise, why an intact basement membrane keeps them confined, how they still obstruct, bleed or secrete, and why some adenomas can progress to carcinoma.
By the end, you can
- Distinguish papillomas from adenomas by the epithelium they copy, and give examples from several organs.
- Describe the gross and microscopic appearance of a papilloma, a gut adenoma and an encapsulated adenoma of a solid gland.
- Explain why a benign epithelial tumour stays above an intact basement membrane and does not metastasise.
- Relate obstruction, bleeding and hormone excess from benign epithelial tumours to their growth and function.
- Explain the adenoma-carcinoma sequence and the features that raise the risk of progression.
What it is
A benign epithelial tumour is a clonal growth of epithelial cells that stays above an intact basement membrane: it does not invade or metastasise. Tumours of surface (covering) epithelium growing as fronds are papillomas; tumours that form glands or arise from glandular epithelium are adenomas. Some, notably adenomas of the gut, are precursors of carcinoma.
4 types to tell apart
- Papilloma
- Exophytic fronds of surface epithelium (squamous or urothelial) on fibrovascular cores: squamous papilloma, common wart, urothelial papilloma, intraductal papilloma of the breast.
- Adenoma of the gut lining
- A mucosal polyp of dysplastic glandular cells, tubular, villous or tubulovillous, with low- or high-grade dysplasia; a recognised precursor of adenocarcinoma.
- Adenoma of a solid gland or organ
- A well-circumscribed, often encapsulated nodule of cells resembling the parent gland (thyroid, parathyroid, adrenal cortex, liver), often functioning; seldom progresses.
- Cystic and mixed forms
- Cystadenomas form cysts (ovary); a fibroadenoma (breast) includes stroma, and a pleomorphic adenoma (salivary gland) mixes epithelium with myxoid matrix.
US spelling: tumours → tumors, tumour → tumor, oesophagus → esophagus.
Normal function
Surface linings and glands on a basement membrane
Epithelium covers surfaces, lines cavities and forms glands. Covering epithelium suits each site: where a surface is rubbed (skin, mouth, oesophagus, cervix), where it must stretch (urinary tract) and where it absorbs and secretes (stomach and intestine). Glandular epithelium grows down from a surface into ducts and secretory units: exocrine glands such as the breast and salivary glands release their product through ducts, and endocrine glands such as the thyroid, parathyroid and adrenal cortex release hormones into the blood.
Every epithelium rests on a , a thin sheet of matrix that anchors it and separates it from the beneath. Epithelium has no blood or lymphatic vessels of its own; its cells are fed by diffusion from capillaries below the membrane, hold tightly to one another, renew from a dividing basal or crypt compartment and mature as they move away from it.
These two families, surface and gland, are the basis of naming: a benign tumour that copies a surface epithelium is usually a papilloma, and one that copies a gland is an adenoma.
Underlying change · Step 1 of 5
A clone that grows but keeps its place
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 9 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
Papillomas: fronds of surface epithelium
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 9 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 3 of 5
Adenomas: tumours that copy glands
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 9 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
Why they stay confined, and how they still cause harm
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 9 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
From adenoma to carcinoma
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 9 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 9 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 9 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 9 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 .