Skin cancer is the abnormal growth of cells in the epidermis that is the outer layer of the skin. The unrepaired DNA damage resulting in the mutation of the skin cells.
Structure of the skin:
The skin consists of an outer epidermis and acts as an barrier. The dermis is found beneath the epidermis and it consists of hair follicle, sweat glands and connective tissues network. The deepest part of the skin tissue contains fat and connective tissue
These cancers most often develop on skin areas typically exposed to the sun, especially the face, ears, neck, scalp, shoulders and back.
Skin cancers, i.e., basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma, are the most frequent tumours.
This factor is mainly based on the inherited factors and longtime exposure to the UV rays and sunlight.
This UV rays results in damage to the DNA repair mechanisms and results in the mutataion of the cells.
Various repair mechanisms exists to maintain the integrity of the skin epidermis. For example when the the skin is exposed to the UV light and the damage to the DNA occurs. This can be repaired by the process known as apoptosis by the body mechanism. This occurs under the control of the p53 suppressor gene.
Other main factor Fas-ligand a member of the tumour necrosis(cell death) superfamily, which is mainly expressed in the basal skin layer it acts as an key surveillance molecule involved in the elimination of the cells which are exposed to the severe sun burns. This factor also prevents the cells from cell transformation.
However the long term exposure to the UV light exposure downregulates this FasL expression in the keratinocytes and melanocytes leading to loss of its sensor function.
Mutation in the p53 gene is the starting point for the formation of squamous cell carcinoma and some forms of basal cell carcinoma.
The transcription factor Gli2 plays a vital role in this pathway , Gli2 is responsible for the marked apoptosis resistance of the BCCs. The formation of malignant melanoma is very complex. Melanocytes form nevi and from the nevi melanoma can develop through mutations in various genes. Once the keratinocytes or melanocytes have been transformed they re-express FasL which may allow the expanding tumor to evade the attack of immune effector cells.
Types of skin cancer:
Basal cell Carcinoma:
This type of skin cancer occurs mainly in the areas exposed to the sunlight like the head and neck. Basal cell carcinoma grows very slowly and they spread slowly or metastasizes to the nearby lymphnodes or even to more distant parts of the body.
The basal cell carcinoma shows higher rate of recurrence. Regular check up for the size. Site, location and other things should be examined. The following history should be taken into account for skin cancer.
Squamous cell carcinoma:
This skin cancer accounts for second most common type of skin cancer. They develop from the flat squamous cells that make up the epidermis, the outermost layer of the skin.
This type of skin cancer is usually found on areas of the skin that have been exposed to the sun, such as the neck, ears, face or the back of the hand, but they may develop in other areas, such as in scars, skin ulcers or the genital region. Squamous cell carcinoma spreads very slowly.
Melanoma:
It is a form of cancer that forms in the malocytes or the skin cells that produces the brown pigment known as melanin. These melanin cells gets darken when they are exposed to the UV rays and this acts as a shielding mechanism.
Merkel Cell Carcinoma:
Merkel cells are the nerve receptors of the skin and they are mainly related to sense of touch. Merkel cell carcinoma are more common in the skin areas which is exposed to the sun such as the face and scalp. People aged 50 and who are immunocompromised are at higher risk of developing this type of cancer. This merkel cell carcinoma have the ability to spread to the vital organs such as bone, lung, liver.
Rare skin cancers
Other skin cancer types are very rare, including these:
Kaposi Sarcoma:
It is caused by the human herpes virus 8. This cancer usually appears as the lesion or tumours on the skin. Tumours might also forms in the mouth, lungs, digestive tract.
Actinic Keratosis:
It is the precancerous growth that might develop into the squamous cell carcinoma if it is left untreated. These are revealed as clusters on skin damaged by exposure to ultraviolet radiation (UV).
Lymphoma of the skin:
It is a type of Non Hodgkin lymphoma. They are mostly found in the lymph nodes which are scattered throughout the body that produces disease fighting the T- cells and B cells also known as lymphocytes. But lymphomas can develop in other lymphoid tissue such as spleen, bone marrow and skin.
Keratoacanthoma:
They are typically benign non cancerous tumours that grow slowly and they can goes away normally.
A firm red nodule on the skin which causes prolong itchiness or burning sensation
Brown or blackish pigmentation
Scaly patches of skin
A mole that changes colour or size and also sometimes bleeds on touch
Physical examination:
During this physical exam, the doctor might note the size, shape, color and texture of the areas in the skin. The doctor might also look for the bleeding, oozing or crusting. The site of the Mole should be checked and anyother spots that could be related to the skin cancer.
The doctor may palpate the lymph nodes under the neck,underarm,groin near the abnormal area. When melanoma starts it often spreads to the nearby lymphnodes first making them larger.
Skin biopsy:
The doubtful skin spot is removed and it is viewed under the microscope.
Shave (tangential) biopsy:
The outermost layer of the doubtful skin spot is shaved and the spontaneous bleeding is stopped by oinment, or by electrical current to cauterize the wound.
Punch Biopsy:
The punch biopsy tool on the skin is rotated and all the layers of the skin is cut to obtain the better results.
Excisional biopsy:
Removing the entire skin tumour for examination. This is the preferred method of biopsy for suspected melanoma.
Incisional tumour:
This removes only the part of the tumour for examination.
Optical biospies:
These are newer method of biopsy such as reflectance confocal microscopy (RCM) can be done without needing to remove the skin.
Fine Needle Aspiration Biopsy:
It is used to detect the metastasized cancer in the nearby lymph nodes. And it is mainly seen in the melanoma cases.
Sentinel lymph nodes:
If melanoma has been diagnosed and has any concerning features (such as being at least a certain thickness), a sentinel lymph node biopsy (SLNB) is often done to see if the cancer has spread to nearby lymph nodes, which in turn might affect treatment options. This test can be used to find the lymph nodes that are likely to be the first place the melanoma would go if it has spread. These lymph nodes are called sentinel nodes
Imaging Test:
Dermatoscopy:
The doctor uses the light and lens to see the skin spots clearly.
Chest X ray:
It looks for:
Enlarged lymph nodes in the center of the chest which is called as mediastinal lymph nodes.
Enlarged thymus gland
Buildup of fluid between the lungs and the walls of the chest(called pleural effusion)
Lung infection(called pneumonia)
CT scan:
A computed tomography special x ray equipment to reveal 3D and cross sectional images of organs, skin tissues, bones and blood vessels inside the body.
Magnetic resonance imaging:
It uses magnetic waves and radiofrequency waves tp view 3D pictures of the tissues and organs. It also can reveals the metastasis has happened or not.
Ultrasound:
It uses high frequenct sound waves to make the image structure in the body. It also checks if internal organs such as kidney, liver or spleen have been affected by leukaemia or not.
Positron emission Tomography Scan:
It is most useful in diagnosing the advanced stages of cancer.
Blood Test:
The level of the Lactate Dehydrogenase should be checked for any distant spread.
The 5 year survival rate for stage 1 cancer is 95%
For stage 4 cancer is 62%.
Avoid exposure to sunrays, UV rays.
Use full sleeve dress to protect yourself from sun
Follow healthy lifestyle
Observe any new moles in the skin.
