Epithelial Tumors
Written by Rhiana Devadasan
BENIGN EPITHELIAL TUMORS
They are sub-divided according to their origin from different types of epithelium:
1. Tumor of Integumentary (lining) Epithelium = Papillomas
2. Tumors of the Glandular Epithelium = Adenomas
Papillomas
Characteristics
- Benign tumor
- Originates from skin and mucus membranes
- Looks like a ledge or bush of branching papillae
- Exophytic tumors
- Slow growth
- Base of tumor = CT containing BV
- Continuation of subepithelial CT lined by epithelium
- May be firm or soft
- e.g. Squamous cell papilloma (oral cavity, larynx, etc.)
i) Firm Papillomas
- located on skin & mucus membranes
- lined by multilayered squamous epithelium (mouth, larynx, pharynx)
ii) Soft Papillomas
- consist of thin fibro-vascular cores with thin-walled vessels
- lined by cylindrical, transitional or ciliated epithelium
- thin branching papillae can be easily injured & bleed
- rapid growth
- papillomas of urinary tract can lead to malignancy (found in neck of urinary bladder & region of trigonum)
Adenomas
Characteristics
- Benign epithelial tumor.
- Originates from epithelium of glands & glandular organs.
- Can be found in breast, thryoid gland, liver, ovaries, prostate gland, GIT.
- Adenomas from compact organs (liver, adrenal gland) can be composed of parenchymal cells separated by a thin layer of stroma.
- Thus, adenoma structure = similar to that of the original organ (and therefore functionally similar).
- Adenomas of mucous membranes = mucus
- Adenomas of the medulla of adrenal medulla = noradrenaline
- Adenomas of beta cells of pancreas = insulin
- Adenomas have atypical structure (absence of ducts, variety in shape, size, location, parenchyma:stroma ratio).
- Cystadenomas: in some adenomas, glandular cavities are widened & form large cavities (called cysts) filled with serous fluid or mucus.
- Histologically: can be tubular, trabecular, cystic, villous, papillary or alveolar.
- E.g. Fibroadenoma (benign breast tumors made of stromal & epithelial tissue)
Tubular Adenoma
- glandular cavities resembling ducts in the CT
Papillary Adenoma
- finger-like projections towards the cavity
Cystic Adenomas
- cyst-like dilation of the glands
Alveolar Adenoma
- numerous bubbles lined by ccylindrical / cubic epithelium in CT