In order to understand your skin cancer pathology report, you need to know a little more about human skin. Your skin is quite complex. It replaces itself entirely every 4-6 weeks and consists of several layers.
The thin, uppermost layer is called the epidermis and it’s around <1mm thick even though it's made up of 5 distinct levels. The epidermis is made mostly of cells called Keratinocytes, which migrate up from the stratum Basale, the lowest level of the epidermis. As these cells move upwards, they become thinner & more mature. The maturity of the keratinocyte cells defines the nature of each level of the epidermis.
The 5 layers of the epidermis, from top to bottom, are:
This is the uppermost layer of the Epidermis and consists of dead keratinocytes. In this layer, the cells are filled with keratin, the same tough protein that makes up your hair and nails. The stratum corneum acts as a protective barrier.
A thin layer of dead skin cells that helps the skin stretch and resist friction damage, particularly around the soles of your feet and palms.
The middle layer of the epidermis, consisting of flat Keratinocytes that have no nuclei or centre. When doctors measure melanomas to see how far they’ve penetrated, known as the Breslow thickness, these measurements start from The Stratum Granulosum.
A layer of spiny cells that gives your skin its strength.
The deepest part of the epidermis where cells (keratinocytes) replicate and begin their journey upwards. This layer also contains melanocytes, the cells that produce melanin to determine skin colour.