Dermatology
Mohs Surgery:
Mohs micrographic surgery is a very labour and time consuming dermatologic surgical procedure in which the highly-trained skin surgeon acts both as a surgeon and pathologist to partake in tissue sparing procedures with highest cure rate for most cutaneous malignancies.
Traditionally skin cancers like basal cell carcinoma (BCC), squamous cell carcinomas (SCC) are excised with specific safety margin (0.5-1 cm) to obtain approximately 95% curate rate. However, when skin cancers occur in cosmetically sensitive areas (face, lips, ear, nose, finger, genitalia) or histologically demonstrate more aggressive behaviours, they are at high risk of recurrence or metastasis. These patients are good candidates for Mohs surgery. This tissue sparing technique allows the surgeon to remove a layer of skin with minimum margin around clinically obvious tumor. The tissue gets processed right away in the clinic and the surgeon review the slides. A map of tumor with area around the tumor which are still positive for malignancy are marked. The surgeon removes another layer only at positive margins and repeat the process till all the peripheral and deep margins are clear from malignant cells. The entire process can take from few hours to days since it can be very difficult with naked eye to predict how extensive the tumor had grown.
PARS® technology could potentially provide a crude demarcation margin for the tumor and significantly expedite the procedure since the surgeon would take a proper margin with high likelihood of removing the entire tumor in the first stage. PARS® benefits for Moh’s surgeries are as follow:
Utilizing PARS® technology to non-invasively demarcate the extend of the tumors could provide significant benefit for general dermatologists, plastic surgeons, Ear-Nose-Throat surgeons as well as family physicians. All these physicians may perform blind mucocutaneous surgeries with intention of complete excision of malignant and non-malignant lesions. Considering the significant difficulty in delineating the proper surgical margins clinically, they would follow the established surgical margin guidelines which has been established for some types of cutaneous lesions. However, significant of those cases would require re-excisions (especially for malignant lesions) since the pathologist may notice positive peripheral or deep margins. Having the PARS® technology at their tool box would provide significant benefit for the surgeons as well as patients by having the ability to remove the entire lesion in one operation and potentially eliminating the need for re-excision.
Mohs micrographic surgery is a very labour and time consuming dermatologic surgical procedure in which the highly-trained skin surgeon acts both as a surgeon and pathologist to partake in tissue sparing procedures with highest cure rate for most cutaneous malignancies.
Traditionally skin cancers like basal cell carcinoma (BCC), squamous cell carcinomas (SCC) are excised with specific safety margin (0.5-1 cm) to obtain approximately 95% curate rate. However, when skin cancers occur in cosmetically sensitive areas (face, lips, ear, nose, finger, genitalia) or histologically demonstrate more aggressive behaviours, they are at high risk of recurrence or metastasis. These patients are good candidates for Mohs surgery. This tissue sparing technique allows the surgeon to remove a layer of skin with minimum margin around clinically obvious tumor. The tissue gets processed right away in the clinic and the surgeon review the slides. A map of tumor with area around the tumor which are still positive for malignancy are marked. The surgeon removes another layer only at positive margins and repeat the process till all the peripheral and deep margins are clear from malignant cells. The entire process can take from few hours to days since it can be very difficult with naked eye to predict how extensive the tumor had grown.
PARS® technology could potentially provide a crude demarcation margin for the tumor and significantly expedite the procedure since the surgeon would take a proper margin with high likelihood of removing the entire tumor in the first stage. PARS® benefits for Moh’s surgeries are as follow:
- Significantly reduce the operations times from hours-days to less than 90 minutes.
- Provide significant financial relief for health care since the Moh’s surgeons are paid for each layer of the skin that they remove, some procedures may require 8 layers or even rarely more than 20 layers have been reported
- Provide significant tools for surgeons to plan the procedures, since if the surgery is extensive, patient may need to be referred to ENT or plastic surgeon to perform the final wound closure under general anesthesia
- Provide clue with regards to whether the tumors have invaded the peri-neural area or not since patients may benefit from radiation therapy post-surgery in cases of extensive peri-neural invasion
- The current wait time for Moh’s surgery ranges from 4 months in Alberta to 12 months in British Columbia. Expediting the procedure would provide significant opportunity for the surgeons to plan their surgical day properly and perform more cutaneous surgery to reduce the extensive wait time.
Utilizing PARS® technology to non-invasively demarcate the extend of the tumors could provide significant benefit for general dermatologists, plastic surgeons, Ear-Nose-Throat surgeons as well as family physicians. All these physicians may perform blind mucocutaneous surgeries with intention of complete excision of malignant and non-malignant lesions. Considering the significant difficulty in delineating the proper surgical margins clinically, they would follow the established surgical margin guidelines which has been established for some types of cutaneous lesions. However, significant of those cases would require re-excisions (especially for malignant lesions) since the pathologist may notice positive peripheral or deep margins. Having the PARS® technology at their tool box would provide significant benefit for the surgeons as well as patients by having the ability to remove the entire lesion in one operation and potentially eliminating the need for re-excision.
True one to one comparison of PARS® and bright-field images of hematoxylin and eosin (H&E) stained human skin tissue with basal cell carcinoma (BCC). a) (1) 5x bright field image of tissue with BCC demonstrating the border of invasive cancer (bottom of red border) versus normal tissue (top of red border). (2) PARS image of the same unstained sample with BCC, the same red border denotes the cancer boundary. Scale Bar: 200 µm b) (1) 20x bright field image demonstrating the same cancer margin as in (a.1, a.2). (2) Enlarged section (green box) of the PARS® image (a.2) compares the disorganized cellular architecture seen in the light microscopy (b.1) and PARS® images (the same red border separates cancerous and normal tissues). Scale Bar: 100 µm c) (1) 20x bright field of tissue with clearly identifiable atypical nuclear morphology, size and distribution. (2) Enlarged section (red box) of the PARS® image (b.2), providing a near perfect match to the brightfield histology image (c.1). Scale Bar: 40 µm. (Dynamic range presented in decibels). [Unpublished, Under Review].
PARS® imaging performed on frozen sections from a Mohs procedure. (a) and (b) show WFOV single-color acquisitions of two separate entire frozen sections. Inset with (b) is an image of the unstained section mounted on a glass slide. (c) shows a higher density scan of the highlighted region in (b). (d) shows a smaller FOV of the highlighted region in (a) captured with the two-color system along with (e) the adjacent section stained with toluidine blue captured on a standard bright-field microscope. (f) shows a neary region of healthy tissue captured on the two-color PARS® which was likewise taken from the highlighted region in (a). [Sci Rep 10, 19121 (2020). https://doi.org/10.1038/s41598-020-76155-6].