How deep does Moh's surgery go in removing Basal Cell Carcinoma on scalp?

Hello!  Thank you for your question!  Moh's Surgery will serially excise thin slices and evaluate each slice under a microscope, ensuring complete excision of the skin cancer.  Although very rare, BCC can be locally aggressive, but unlikely.  If by chance, there is direct invasion to surrounding structures, your Moh's surgeon will likely refer you to a surgeon for management of that particular area.  This is a very unlikely scenario given a BCC.  Moh's Surgery has excellent literature showing minimal recurrence rate.  Best wishes!

Almost all basal cell carcinomas (with few exceptions) do not invade into bone.  The Mohs surgeon will take small portions of tissue at a time until the entire cancer is gone and then place sutures to bring the edges back together.  While liquid nitrogen did not do the trick, Mohs surgery ensures that the entirety of the skin cancer is removed.  The doctor will be looking at the tissue s/he takes out under the microscope to ensure this, and rest assured, the clearance rate with this treatment option is better than any other available.  Do see someone who is a member of the American College of Mohs Surgery for your care. 

Even though it does not feel like there is a lot of skin on the scalp, there is actually quite a bit. The way it works is that your surgeon will do an excision (based on the biopsy report) and remove tissue just as deep (and wide) as he/she believes the cancer lies. Then a slide is made while you wait. The surgeon reads the slide to determine if more cancer is there still - either wider or deeper. If either exists, more tissue is taken and then the process is done again. The layers taken are very thin, so don't worry. This process is done until the slide comes back showing clear margins for the removed tissue - meaning the cancer has been totally excised. Your BCC doesn't go into your bone, so you don't need to worry about them removing bone and fusing it back together. BCCs are tissue cancers so that's all the surgeon will be dealing with. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."