Therapies and diagnostic

A biopsy is a technique where a sample of tissue is taken from the body in order to examine it in more detail. A doctor should recommend a biopsy when an initial test suggests an area of tissue in the body isn’t normal. A biopsy might be recommended whenever there is an important medical question the biopsy could help to answer. For example, in skin where a mole has changed shape or size recently and a melanoma or other skin cancer is possible. The biopsy can be done in the operating room, on the ward or from an autopsy (post-mortem). The step following the biopsy is the analysis of the tissue with the help of an anatomic pathological analysis. Anatomo-pathology is the branch of pathology that deals with tissue diagnosis of the disease. 6Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease. A correct tissue diagnosis is essential before starting the treatment, which can involve surgery, radiation or drugs treatments. Since some treatments can originate more side effects, good disease diagnosis is very important. 5
Histopathological classification of NMSC should be able to identify subtypes that correlate with clinical behaviour and treatment requirements. In addition, the classification should be easy to use and reproducible. 6

Mohs surgery is a procedure used to treat skin tumours and it is an excision surgery where the margins are controlled with a microscope. 16
All types of skin cancer can be treated by Mohs micrographic surgery, when tumours have poorly delimited margins. BCC, AK, and SCC show typical structures in OCT that allow non-invasive diagnosis on the basis of real-time imaging with high sensitivity and specificity. In some cases, dermoscopy is used prior to Mohs surgery because it can delimitate the tumour and increase procedure effectiveness. 16

Mohs surgery has different procedure steps that we can resume below:

  • Anesthesia: The tumour site is locally infused with anaesthesia to completely numb the tissue;
  • Removal of visible tumour: Once the skin has been completely numbed, the tumour is gently scraped with a curette. This helps define the clinical margin between tumour cells and healthy tissue. The first thin, saucer shaped “layer” of tissue is then surgically removed by the Mohs surgeon;
  • Mapping the tumour: Once a “layer” of tissue has been removed, a “map” or drawing of the tissue and its orientation to local landmarks is made. The tissue sections are processed and then examined by the surgeon to thoroughly evaluate evidence of remaining cancer cells. It takes approximately 60 minutes to process, stain and examine a tissue section. During this processing period, the wound will be bandaged and the patient may leave the operating room;
  • Ensuring all cancer cells are remove: If any section of the tissue shows cancer cells at the margin, the surgeon returns to that specific area of the tumour, as indicated by the map, and removes another thin layer of tissue only from the precise area where cancer cells were detected. The newly excised tissue is again mapped, color-coded, processed and examined for additional cancer cells. If microscopic analysis still shows evidence of disease, the process continues layer-by layer until the cancer is completely removed.
  • Reconstruction: Fellowship-trained Mohs surgeons are experts in the reconstruction of skin defects. Reconstruction is individualized to preserve normal function and maximize aesthetic outcome. 16

The following image describes the sequential procedural steps of Mohs Surgery. 16
Mohs Surgery

Mohs Surgery is a selective removal of a tumour that preserves much of the surrounding normal tissue, thereby producing a better aesthetic result. Since this systematic microscopic search reveals the roots of the skin cancer, Mohs surgery offers the highest chance for complete removal of the cancer while sparing the normal tissue. Cure rates typically exceed 99% for new cancers and 95% for recurrent cancers. In normal surgery only 0.01% of margins are analyzed. 16

Thus, OCT can complement dermatoscopy, because of its increased resolution resulting in a more detailed discrimination between healthy and neoplastic tissue. This means that OCT observation of the delimitation of the tumour can now be obtained with much higher precision. 15

Optical Coherence Tomography (OCT) has the potential for in vivo imaging of non-melanoma skin cancer (NMSC). By allowing identification of sub-surface margins of NMSC lesions, the use of OCT could improve the rate of complete excision and reduce the average number of stages during Mohs micrographic surgery (MMS).

Evidence that OCT can be used to identify NMSC tumour margins and a larger prospective trial of OCT imaging in conjunction with MMS is currently underway. Therefore, OCT can obtain higher resolution and allows more accurate delimitation of the tumour compared to other methods currently available such as Digital Dermatoscopy. 16

Mohs Surgery with DD & OCT technology

The Mohs surgery workflow with the support of NITID brings some advantages for the patient and the dermatologist. Prior to surgery, patients indicated for this procedure must be subjected to complete margins delimitation. This can be performed with enhanced accuracy with the help of the DD & OCT integrated technology. Subsequently, the surgeon removes the lesion for analysis with the help of a microscope. The next step is to use OCT to check if the margins are totally free of cancer cells.

The Mohs Surgery procedure, supported by DD & OCT technology, can save time and enhance the safety and effectiveness of the procedure. Prior to surgery, delimitation of margins with DD & OCT can increase lesion diagnosis accuracy and thereby facilitate all the removal of all the affected tissue. In terms of the general costs to the hospital, less time using the operating room is money and time saved. This can allow significant savings and consequently have the potential of treating more patients per day.

The image below describes the workflow process of the Mohs Surgery with the NITID imaging device that incorporate DD & OCT technology at the same time.