PATHOLOGY PRACTICAL

• Introduction• Most common skin cancer arising from the �

basal layer of epidermis and its appendages• Low metastatic potential�• Locally invasive, aggressive, and destructive �

to skin and bone

• Epidemiology• Skin cancer: approx. 1.5 million cases per year�• BCC is most common skin cancer 80% is BCC�• White >> Black �• Men >> women�• BCC increase with age�• Aged 55--70 has 100 fold higher �• incidence of BCC than age 20 and younger• Striking geographic variation�• Higher incidence closer to the �• equator• *Australia is 40X that of Finland 80%�

• Clinical presentation • A round, nodular, pearly tumour is present

on the left cheek. • The presence of dilated, sub epidermal blood

vessels (telangiectasia's) is characteristic of basal cell carcinomas.

BASAL CELL CARCINOMA

• Macroscopic examination of the slide shows a section of skin and underlying subcutaneous tissue.

• Immediately beneath and elevating the epidermis is a blue cellular tumour composed of multiple variable sized islands of basophilic tissue

• . The margins of the tumour appear smooth and rounded.

• Microscope shows nodular masses of tumour cells (1) extending from the epidermis into the underlying dermal connective tissue and elevating the overlying focally ulcerated epidermis.

• The tumour cells have a fairly uniform monotonous appearance - they are spindle in shape with indistinct eosinophilic cytoplasm and oval basophilic nuclei with indistinct nucleoli (2).

• A characteristic feature of basal cell carcinoma is the tendency of the cells at the periphery of the tumour nests to become vertically orientated (2) and form a palisaded layer.Frequent mitotic figures are seen and this is also a feature of basal cell carcinoma.

• Basal cell carcinomas are believed to arise from a pluripotential cell in the basal layer of the epidermis which has the capacity to differentiate into epidermis and any of its adnexal structures.

• Thus in basal cell carcinomas one may see evidence of keratinisation, hair follicle formation, or sebaceous differentiation.

• These tumours tend to locally infiltrate and ulcerate but rarely metastasise.

Psoriasis