This is an animation demonstrating the tissue processing and unique cutting technique as employed during Mohs Micrographic surgery at the Skinmatters Mohs and Reconstructive Unit. The is an epidemic of skin cancer in the world, with the fastest increase in young adults in the 30’s and 40’s. With this in mind, a case of pigmented Basal cell carcinoma in a young female is demonstrated in this video.
The pigmented Basal Cell Carcinoma is identified. The tumour is removed with a thin layer of surrounding healthy tissue) with a circular incision, usually under local anaesthetic.
All visible tumour is removed but the extend of the tumour is not visible without microscopic evaluation.
The excised tissue is taken to the onsite Mohs Histological laboratory for processing. The tissue block is mapped and prepared for processing in the specialized Mohs frozen section laboratory. The block is cut to the desired size and marked for orientation. Relaxing cuts are made to ensure that matching cuts a lying flat on a histology glass slide to ensure all of the skin edge and deep excision margins (complete cut surface) of the tumour will be seen at sectioning and microscopically evaluated.
The tissue block on the glass slide is turned upside down and embedded on a metal chuck called a stage, and embedded in Cryo-gel, ready for freezing. Once the tissue block is frozen in a specialized Cryostat machine it is ready for sectioning. Tissue sections of approximately 8 micro meters are cut in the Cryostat machine using a microtome.
The thinly sectioned tissue wafers are placed on glass histology slides. The glass slides containing the tissue wafers are then stained with tissues staining dyes. Different stains are used to allow the dermatologist performing the Mohs surgery and Mohs pathology evaluation to identify any skin cancer with a high level of accuracy. The stained slides presented to be examined microscopically by the dermatologist. The different stained allow higher accuracy. The entire cut surface around the skin cancer is examined microscopically for any remaining tumour.
In this case the remaining Basal Cell Carcinoma is identified in the excisional margins. If remaining tumour is found under the microscope like in this example, the tissue still containing the tumour is removed with a subsequent excision stage. Since only the area of remaining tumour is excised, the healthy tumour-free areas are left alone, thereby limiting the size of the defect to the smallest possible while achieving total clearance of a tumour.
On the additionally excised tissue the frozen section process is repeated, and the histology slides produced examined microscopically by the dermatologist performing the Mohs surgery. As soon as the dermatologist confirms that the skin cancer is completely removed, a specialist reconstructive surgeon or the dermatologist proceeds to repair the defect.
Thank you for taking the time to watch this animated explanation of the Mohs Micrographic Surgery process, evaluating 100% of the margin around and underneath the tumour, which is what makes Mohs the world-wide Gold standard treatment with the best cure rate for skin cancer.