Neoplasms in the body can be of two types. These are benign as well as malignant neoplasms. In skin neoplasms are also observed benign as well as malignant kinds of tumours. In certain cases benign neoplasms can be premalignant. Namely, they can predispose to malignancy or become malignant under certain conditions.
Dysplasia of the skin epithelium such as dysplastic nevus is a premalignant medical condition which can tarnsform to a malignant tumour with time. Neoplasms of the skin whether they are benign or malignant can occur in any type of cells that populate the epidermis and the dermal layer of the skin.
These cells range from keratinocytes and melanocytes to cells of the nervous system such as merkel cells and cells of the immune system which are located in the dermal layer of the skin.
An example of a benign tumour that can affect keratinocytes in the epidermis is a viral infection which is called molluscum contagiosum. An example of a malignant tumour that can affect keartinocytes is basal cells carcinoma and squamous cells carcinoma of the epidermis.
An example of a benign tumour that can affect the pigment melanin secreting cells which are melanocytes is a black nevus or mole or a blue nevus or mole. These moles can be congenital or acquired or it can be dysplastic. Both forms of nevi, namely the congenital and the dysplastic forms are potentially likely to transform into malignant tumours.
An example of a malignant tumour that can affect cells of the nervous system in the skin is merkel cells carcinoma. An example of a benign tumour that can affect the nerve endings of nervous system cells in the skin is lack of sensation in tactile nerve endings or in heat nerve receptors in the skin surface.
The immune system cells in the skin can also be target for for neoplasms. A malignant neoplasm that can affect the skin and which involves T cells is cutaneous T-cells lymphoma. On the other hand, a benign tumour that can affect the lymphatic cells in the skin is called lymphomatoid papulosis
Benign neoplasms of the skin keratinocytes are many in number. I will discuss here several of them. Viral infection of keratinocytes of the skin is a benign neoplasm that have under this heading several disorders.
These are first verruca vulgaris or the common warts. This benign condition of the skin is caused by the papillomavirus and is a contagious disease which is transmitted from person to person by skin contact. The fingers are the common site of infection for this disorder. Verruca vulgaris has a distinct skin symptoms on the skin of affected individuals.
Another viral infection which is related to verruca vulgaris and which is called condyloma acuminatum involves the keratinocytes of the epidermis. It is the same as verruca vulgaris with the exception of the warts being larger in condyloma acuminatum. It is caused by a different serotype of the papillomavirus and is transmitted via sexual contact.
Another benign viral infection which affects also keratinocytes is called molluscum contagiosum. It is caused by a virus of the poxvirus group. Spider angioma is a benign condition that is manifested as arterioles telangiectasia which appears on the skin in the form of spiders. It is caused in females during pregnancy. In addition it is also caused due to hepatic failure in affected individuals.
Another benign skin condition that affects keratinocytes is keratoacanthoma. It can mimic cancer in its shape especially basal cells carcinoma. it is characterized by a solitary nodule that can grow rapidly. It remits spontaneously over a period of time.
Benign skin disorders that can affect melanocytes are called nevi. They are usually pigmented due to the presence of the pigment melanin. Nevus that can predispose to cancer are either congenital that is present on the skin from birth or dysplastic or atypical that are acquired. Both of these nevi can become malignant with time.
Malignant tumours that can affect kertinocytes primarily are basal cells carcinoma and squamous cells carcinoma. Both forms can be nodular but basal cells carcinoma can adopt several forms.
Melanocytes malignancy can occur in a preexisting congenital or dysplastic nevus. It is characterized by a lesion that is colored with different types of colors such as black and red and blue.
Melanocytes malignancy is called melanoma. It can have several forms all are colored. One of them is nodular melanoma which is characterized by the presence of a colored nodule in the lesion. Melanoma can also be macular in shape as in superficial spreading melanoma.