CHAPTER FOURTEEN: TUMORS, CANCER ANDMISCELLANEOUS SKIN CONDITIONS
Introduction The integument is the largest organ in the body. It is constantly exposed to the external environment, making it vulnerable to damage from UV radiation, pollution, environmental pathogens and other harmful circumstances. As the skin is under constant stress it is a common site for the development of abnormal tissue. is defined as an abnormal mass of tissue that is involved in some pathological process. The term tumour does not necessarily refer to cancerous tissue; it can be used to describe any abnormal process. The term or neoplasm is used to describe a cancerous tumour. A The term is used to describe a membrane-bound sac containing fluid, air, or a semi- solid material. Generally, the membrane is responsible for the production of the fill material. Occasionally there will be seen a collection of fluid, air or semi-solid material in a tissue without an enclosing membrane. Such occurrences are called pseudocysts or have a specific name that describes the tissue and the fill material.
Tumorous Skin Diseases
Neoplasia/Neoplasm Neoplasia is the
growth of new, abnormal cells within a tissue. The growth of a neoplasm is uncoordinated with the growth of surrounding, normal tissue, and is usually growing at a rate that exceeds the growth rate of the normal tissue. As a neoplasm grows it forms a lump or tumor in the tissue.
Neoplasia can be caused by a number of factors: Oncogenic
disrupt the genes coding for normal growth resulting in the
uncontrolled multiplication of infected cells. Some genetic mutations affect cell differentiation as well as cell growth rate to produce rapidly multiplying, abnormal masses. Environmental work in two ways. Primary carcinogens cause mutations to occur in the genes resulting in loss of differentiation and uncontrolled growth. Secondary carcinogens affect cell division and growth by mimicking chemical signals that trigger cell division. Environmental carcinogens include UV radiation, x-rays, pollution, asbestos, pesticides and industrial by-products. The normal ageing process may also contribute to neoplasia. As the body ages the mechanisms that check the accuracy of DNA replication become weaker, allowing more mutated cells to persist.
Whatever the cause, the process of neoplasia has the same result. Genetic disruption or mutation causes a loss of differentiation and uncontrolled of cells resulting in the
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