1. Benign Tumours of Epithelial Origin
Papilloma
C/f
Age 2-5th decade of life
More in males, can affect an sex
Most common site is tongue, followed by buccal mucosa, lip, gingiva
Clinically- cauliflower like growth, having finger like projections, usually pedunculated, may be sessile, pinkish in colour; if keratinized, then colour is greyish white
Usually painless unless secondarily infected
Resembles verucca vulgaris occuring on fingers, caused by HPV

2. Papilloma Contd.. Histological Features
Each finger like process has a connective tissue core covered by epithelium which is hyperplastic
If keratinized, then para or ortho keratinization is found on the surface of projections
Inflammatory cells may be present if ulcerated surface

3. Keratoacanthoma or self healing carcimoma
It is a benign epithelial neoplasm which histologically resembles carcinoma
Etiology unknown, suggested to be viral, genetic, chemical carcinogens etc.

4. Keratoacanthoma CLINICAL FEATURES:
Usually occurs on external surface like lip, nose, cheek, Zygoma etc.
Age 5th to 7th decade of life
More common in males
1.5 to 2 cm in diameter

5. Keratoacanthoma: Clinical course
Initially appears as nodule, which ulcerates and becomes crater like ulcerated nodule, keratin is present within the ulcer
It grows to its full size in 4-8 weeks, remains static, then in following 6-8 weeks, it expels the central keratin core and heals, hence called as self healing carcinoma, recurrence is rare.

6. Keratoacanthoma Histological Features:
Hyperplastic squamous epithelium growing into underlying connective tissue
Surface covered by thick layer of ortho & para Keratin with central plugging
Occasional dysplastic features are seen in the epithelial cells
At the leading margin of tumour, islands of epithelium appear to be invading connective tissue and it is almost impossible to differentiate it from Squamous cell Carcinoma
Perineural invasion has also been reported, but does not have an adverse effect on biological nature of tumour

7. Keratoacanthoma H/F Contd..
Connective tissue is infiltrated with chronic inflammatory cells
At the margin of the lesion, the normal adjacent epithelium is elevated towards the central portion of crater, then an abrupt change of normal epithelium occurs into Hyperplastic Acanthotic epithelium
Hence, Inclusion of the adjacent border of specimen is must in the biopsy to reach a conclusion.

8. Benign Epithelial Tumors Contd..
Pigmented Cellular Nevus
Nevus is a developmental tumor like malformation, composed of nevus cells.
Melanin pigment is present in tumor cells

9. Pigmented Cellular Nevus
Two types
Congenital
Small cms in size
Garment - more than 10 cms in size
Acquired
Intradermal
Junctional
Compound
Spindle cell type
Blue Nevus

10. Pigmented Cellular Nevus
Congenital Nevus
These are macules, Pale or coloured and are raised or elevated
These subsequently show hair growth on their surface
Are present at birth
Acquired Nevus
Present 2-3 yrs after birth
Number increases till 3rd decade of life, then decrease in number
Usually small in size
Pigmented
With or without hair growth on surface
This type is mostly seen in oral cavity, common sites are palate & gingiva

11. Histopathology:
Main cell is nevus cell. These are large ovoid cells with vesiculated nuclei, and pale cytoplasm
They are derived from neural crest cells

12. Melanocytes in Normal epithelium

13. Normal & benign lesions (melanocyte related)

14. Junctional nevus

15. Compound Nevus Shows junctional activity
& nests of nevus cells in connective tissue.

16. Intradermal Nevus

17. Blue Nevus