Merkel Cell Cancer
The cells that constitute the top most layer of the epidermis are called Merkel cells. These cells are situated closest to the sensory nerve endings that perceive the sense of touch. Of the cancers affecting face and eyelids, Merkel cell cancer is a severe form of skin cancer that is caused by uncontrollable division of cancer cells. The cancer cells spread through the Merkel cells infiltrating the tissue, muscles, subcutaneous fat, lymph nodes and internal organs.
Cause and Symptoms
Caused by MCV (Merkel cell polyomavirus), Merkel cell cancer occurs largely in people who face extreme exposure to artificial Sun light and UV radiations. Elderly people, people with lighter complexion and, people with a weakened immune system due to organ transplants or HIV, are most susceptible to the condition of Merkel Cell cancer.
The symptoms begin with eruption of painless growths on skin. The growths are elevated firm lumps with a deep purple or red colouration. If the symptoms persist in the form of moles and bumps with a rapid growth and, bleed easily on a minor wash or scratch, medical attention must be sought at the earliest.
To understand the nature and source of the tumour, a thorough physical examination is conducted with questions regarding the patient’s age, history of ailments and habits of eating and hygiene. A skin biopsy is conducted by removing the section of the affected area and checking for signs of the cancer cells. The factors that influence the diagnosis of the condition depends on the following conditions:
- Size and spread of the tumourous growth in Merkel cells
- Source of cancer involving face and eyelids.
- Stage or degree of Merkel cell cancer involving face and eyelids.
- Patient’s general health and age
- Probability of recurrence
Stages of Merkel Cell Carcinoma
The cancer cells spread from the source point in the Merkel cells to lymph nodes through the layers of tissue and then, to other parts of the body through the blood vessels. This process in which the cancer cells spread rapidly through the tissue by breaking away from the source is known as metastasis. To evaluate the diagnosis on cancer involving the face and the eyelids, it is important to understand the staging phase of Merkel cell cancer, as mentioned below:
- Stage 0: The cancer cells remain in the Merkel cells giving rise to abnormally shaped painless growths on the skin.
- Stage IA: The size of the tumour gradually increases up to 2 cms. Lymph nodes are unaffected.
- Stage IB: The cancer cells gradually spread into the tissue. Swollen lymph nodes are detected in imaging tests.
- Stage IIA: The tumour continue to grow more than 2 cm.
- Stage IIB: No anomalies are detected in the lymphatic system.
- Stage IIC: The cancer cells spread actively into the connective tissue such as muscles and cartilage.
- Stage IIIA: The cancer cells spread into muscles, bone and tissues. Lymph nodes exhibit signs of cancer cells.
- Stage IIIB: Lymph nodes containing cancer cells are removed after imaging tests. The probability of a secondary cancerous growth is speculated.
- Stage IV: The cancer cells spread into organs like liver, lung and brain.
Tests to evaluate Merkel Cell Cancer
CT scan (Computerised Tomography) is an effective imaging procedure used on cancers involving face and eyelids. The scan gives detailed images of the affected areas within the body from various angles by injecting a dye into the vein of the patient. To check for cancer cells in the lymphatic system, the head and the neck are scanned. If the cancer cells have spread beyond the face, eyelids and lymph nodes then, the chest and abdomen are scanned. MRI Scan is engaged by employing a magnet with radio waves to capture detailed images of the affected areas within the body.
In certain cases, PET scan (Positron Emission Tomography scan) is performed for diagnosis of Merkel cell cancer involving face and eyelids. This scan is performed by injecting a radioactive glucose into the vein of the patient. The glucose tracer can be administered to the patient, orally, nasally or intravenously. The aim of the tracer is to target the areas of the body that exhibit heightened chemical activities that are often associated with disorders and diseases like Merkel Cell Cancer. The areas containing cancerous cells are highlighted in the picture. Besides being used in diagnosis of Merkel Cell Cancer, Positron Emission Tomography scan is also used in assessing brain disorders and hear diseases. PET scans are very effective in detecting Merkel Cancer cells and in evaluating the condition by checking if the cancer cells have spread to other parts of the body. The scan also aids in detecting chances of recurrence of Merkel Cell Cancer and, if the treatment is working or not, for the patient.
Doctors specialised in diagnostic techniques study PET scans to detect Merkel cancer cells thoroughly as, the imaging pictures clicked in the scan can detect non-cancerous areas too, which may appear bright because of increased chemical activity and, may not necessarily pertain to Merkel cell cancer.
Immunohistochemistry is another effective diagnostic procedure performed on cancers involving face and eyelids. This procedure is performed by injecting the sample target tissue with a combination of monoclonal and polyclonal antibodies to target specific antigens in the target tissue.
Immunohistochemistry (IHC) is an important application of monoclonal as well as polyclonal antibodies to determine the tissue distribution of an antigen of interest in health and disease. IHC is widely used for diagnosis of cancers; specific tumor antigens are expressed de novo or up-regulated in certain cancers. This article deals with the various applications of IHC in diagnosis of diseases, with IHC playing an important role in diagnostic and research laboratories.
KEY WORDS: Antibody, antigen, disease, immunohistochemistry
When cancer cells spread into lymph nodes, the sentinel lymph node is the first to be affected. Therefore, in cases of these cancer involving the face and eyelids, a Sentinel lymph node biopsy is performed by injecting a dye into the lymphatic system. The dye is absorbed by the target lymph node tissue. If cancerous cells are detected in the tissue sample, a wide excision is performed by removing the tissue. Following which, a regional dissection is performed by removing lymph nodes surrounding the affected area. However, a radical lymph node dissection is performed if stage IV is reached. Radiation therapy involves focussing a high energy X-ray beam on the area of treatment, to kill and stop the spread of the cancer cells. Internal radiation therapy involves sealing of the radioactive substance in the needles, catheters and wires that are inserted in the target site of treatment. Chemotherapy is resorted to, if cancer cells are invisible in the lymph nodes.
Post treatment, patients are advised for follow up tests to assess the possibility of incomplete recovery or, recurrence of Merkel Cell cancer. Doctors like Dr. Debraj Shome have specialised in the oncology aspect of dermatology by handling extensive surgeries on cancers involving face and eyelids.