Squamous cell carcinoma :
It is the malignant tumour arising from the squamous cells. In the case of skin, it is the prickle cell layer from where Squamous cell carcinoma arises. It also arises from the stratum basale of the epidermis.
1. Any part of the skin or its appendages, e.g in face, dorsum of the hands, sole, palm etc.
2. Junctional region of the skin and mucous membrane e.g lip, penis, anal region, vulva etc.
3. Mucous surface covered by stratified squamous epithelium e.g
I. Upper air passage or food passage- tongue, buccal cavity, pharynx, larynx, oesophagus.
4. Occasionally it may arise from the columnar cells undergoing metaplasia, e.g in gall bladder, bronchus, cardiac end of the stomach etc.
- SCC is the 2nd most common form of skin cancer.
- It usually affects the elderly.
- It is twice as common in men.
- It is relatively common in white- skin individuals living nearer the equator.
- It is more malignant and rapidly growing than BCC and 4 times less common than BCC.
a) De novo, i.e. it may arise in a previously normal area exposed to sunlight.
b) On some pre-existing skin lesion e.g.
- Senile keratosis
- Bowen`s disease
- Erythroplasia of queyrat
- Xeroderma pigmentosum
- Lupus vulgaris
c) SCC is also associated with chronic inflammation (chronic sinus tracts, pre-existing scars, osteomyelitis, burns, vaccination points). When a SCC occurs in a burn scar, it is called a Marjolin ulcer. This lesion may appear many years after the original burn. It tends to aggressive and prognosis is poor.
d) SCC is associated with immunosuppression (organ transplant recipients)
e) Exposure to ionizing radiation.
f) Prolong exposure to certain chemicals ( carcinogens) e.g. pitch, tar, arsenicals etc.
g) Infection with HPV5 and HPV16.
h) Current and previous tobacco use doubles the risk of SCC.