Can I tell how big my BCC (Basal Cell Carcinoma) was by my reconstruction skin flap that measured 2cm x 2cm? I had Mohs Surgery and the margins were clean.
Estimating Size of BCC Through Skin Flap?
Doctor Answers (6)
Size of Skin Cancer and Relationship to Size of Flap
Generally speaking, the size of the flap incision will be significantly longer than the size of the actual skin cancer to achieve an acceptable aesthetic result. If you have questions about how large the lesion was, ask your Surgeon or ask for a copy of the operative report which should contain that information. Pathology specimens "shrink" to some degree after removal and are less reliable as a measure of lesion size.
Estimating the size of a tumor based upon the reconstruction
You cannot estimate the size of your tumor based upon the size of the reconstruction. Although generally a small reconstruction implies a small tumor it is not always the case. The reconstruction size is based upon the defect location, defect size, laxity of skin, and vascularity of skin in the defect location.
How to judge how bit the skin cancer was from a flap that was done during reconstruction
After Mohs surgery, or any excision of a skin cancer, the defect left can be closed by a skin graft, which is a patch of skin harvested from elsewhere on your body. The size of the graft is then the size of the skin cancer plus a narrow margin. If a flap were done from the adjacent area, then it depends what type of flap was done. It is difficult usually to tell how big the skin cancer was because the flap usually has to remove some extra skin so that the contour of the resulting skin is flush with the surrounding tissue. The most accurate way to find out how big the cancer was in diameter, is to ask the Mohs surgeon. If a one millimeter margin is taken, then you can subtract 2 mm. from the defect size to obtain the cancer size (1mm. on each side of the tumor increases the diameter by 2mm.).
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Why Estimate? Ask!
It is very difficult to estimate the size of a skin cancer based on the size of the flap that was used for reconstruction. There are many factors that determine the size of a flap including what type of flap was used, where is the defect (proximal nose vs. distal nose), the sebaceous quality and elasticity of the skin, etc Just ask the doctor. He or she should have a record of how large your skin cancer defect was before the reconstruction.
Size of your basal cell carcinoma
The size of your basal cell carcinoma can never be estimated from the size of a reconstruction skin flap. Once a cancer is removed by Mohs surgery there has been a small 1-2mm margin of normal skin that was removed to get the clear margins. Generally the cancer can be considered to have been the size of the final defect minus the margins that were taken. The advantage of Mohs over other excisional surgeries is that it spares over 180% more healthy tissue that the other techniques. Because Mohs surgery looks at 100% of the excised margins, a very narrow safety margin is taken to leave the smallest area that will need to be sutured. By contrast, traditional excisions of cancers look at less than 1% of the margins so a much wider safety margin of healthy is needed to achieve an acceptable cure rate. Don't forget that for most cases, you have a 99% cure rate with Mohs as compared to 90% or less with other procedures or techniques for cancer removal.
The path report should have the answer to BCC size
When a skin cancer is removed, and a microscope is used to examine the margins(this can be done by a pathologist-frozen section or a dermatologist - Mohs) the path report should have the answer. The size of the defect will affect the size of the flap closure but there are other variables the reconstructive surgeon must consider, such as the shape(long and narrow vs round) ,position on the face(cheek is easier to close than nose), blood supply to the flap, etc. As long as the result is good and the margins are free, th question should be moot.