Skin Cancer Diagnosis
Skin Cancer Diagnosis
Harry Saperstein, MD, FAAD (Dermatologist, Clinical Assoc. Professor, Medicine, Private Practice and UCLA) gives expert video advice on: What types of biopsies are used to diagnose skin cancer?; What is "microscopic ulceration" and why is it important in diagnosing skin cancer?; What is "lymphoscintigraphy" and how does it help detect skin cancer?
What types of biopsies are used to diagnose skin cancer?
When a patient presents in the office with a lesion, which may or may not be a skin cancer, we need tissue in order to identify under the microscope both whether it's a skin cancer or what type of skin cancer it is. There are numerous ways that we can do that, but all of them require some sort of tissue sampling, also known as a biopsy. There are several different types of biopsies that can be taken.First, there's something known as a shave biopsy, which is taking the top and some of the bottom part of the lesion off. Second, there is a punch biopsy, which is something that is done by taking a small core of the lesion, which is narrow but deep.There is an incisional biopsy, which is taking part of the lesion out in total.And there is an excisional biopsy, which is removing the entire lesion and submitting that for pathological confirmation.The type of biopsy used is dictated usually by the type of lesion we suspect, and by some cosmetic considerations as well. We need to be doing multiple biopsies in order to determine whether or not patients have skin cancer and so we need to do them in such a way that it's not such a cosmetic or financial burden that patients will be hesitant to do them. So we need to make them as easy for the patient as possible, at the same time get the information that we need.
What is "microscopic ulceration" and why is it important in diagnosing skin cancer?
When the biopsy is done of a malignant melanoma, one of the things that is looked at is the nature of the cells; the cells as they invade in the epidermis down into the dermis, as well as whether or not the epidermis is ulcerated. When the epidermis is ulcerated, the lesion, despite all other factors, is considered a more likely lesion for metastasis and is clicked up a half notch in the staging. Ulceration is considered a sign of some aggressiveness and will mirror a greater possibility of metastasis.
What is "lymphoscintigraphy" and how does it help detect skin cancer?
When a malignant melanoma is identified on the skin after the biopsy is taken, if it is of a certain invasiveness into the dermis, it is considered at some risk for metastasis to the local lymph node. When that is felt to be the case, a special procedure called a sentinel node biopsy is taken. That is done by the process of lymphoscintigraphy; injecting a radioactive dye into the melanoma, and then tracing it radioactively to the first lymph node which that dye goes to. That is considered the sentinel node, or the sentry node, which in a way protects the other nodes from getting a metastasis. It is felt that if the node that lights up is negative for malignant melanoma, then all the other nodes after will be equally negative. That is when a sentinel biopsy and lymphoscintigraphy are done, and it has prognostic significance to the patient.