Efficacy and Safety of Slow Mohs Micrographic Surgery for Treating Nail Apparatus Melanoma in Situ

TAKE-HOME MESSAGE

• A total of 10 patients were included in this retrospective study from China to evaluate the safety and efficacy of slow Mohs micrographic surgery (MMS) for the treatment of nail apparatus melanoma in situ (NAMIS). The procedure was well-tolerated, with no local recurrence during a median follow-up time of 46 months. A median number of two stages and a median margin of 8 mm were required.
• This case series demonstrates the successful use of slow MMS in achieving optimal outcomes and preserving nail function in patients with NAMIS.

–  Ruth McTighe, MD

Written by



John Zitelli MD

The two articles by Le and Zhang provide real-world evidence that Mohs surgery is an effective treatment for melanoma in situ (MIS) of the nail unit. Is this evidence-based practice changing? The preponderance of evidence to date, including these articles, confirms that Mohs is at least non-inferior. There are no randomized controlled trials, nor will there likely be one. But, as pointed out in a recent JAMA article, real-world evidence has a meaningful role in health care decision-making, and this evidence supports the value of Mohs surgery in nail unit MIS.^1,2 Although the number of patients is small, comparison of raw recurrence rates may be misleading; the pooling of data helps to strengthen the evidence.

These reports have weaknesses repeated in many case studies and reviews. First, they do not define local recurrence. All studies should define local persistence and separate persistent disease recurrence from satellite metastatic disease. This might be a moot point because these reports were for MIS, and any local recurrence was likely due to persistent disease; nonetheless, the distinction is important. Second, follow-up time is extremely important. Most local recurrences from persistent disease occur later than metastatic disease (5 years vs 2 years). All studies should specify how long patients were followed, and Kaplan–Meier statistics should help extrapolate the data to provide a projected 5-year recurrence rate.

My opinion based on my treatment of dozens of nail unit MIS is that Mohs is extremely valuable when performed properly. Mohs surgery with frozen sections and Mart 1 immunostaining is the most accurate way to assess the margin. The use of blue Mart 1 improves detection of melanocytes.³ Fellowship training is valuable due to the increased difficulty of removing layers from the nail bed, periosteum, nail horns, and even bone when necessary. In the end it all comes down to – should 100% of the margin be examined by Mohs, or is it good enough to sample less than 1% of the margin with traditional pathology exam? The controversies about the value of Mohs surgery for melanoma are melting away.

References

1. Wang SV, Schneeweiss S, Franklin JM, et al. Emulation of Randomized Clinical Trials With Nonrandomized Database Analyses: Results of 32 Clinical Trials. JAMA. 2023;329(16):1376-1385. https://jamanetwork.com/journals/jama/article-abstract/2804067 
2. Sheldrick RC. Randomized Trials vs Real-world Evidence: How Can Both Inform Decision-making? JAMA. 2023;329(16):1352-1353. https://jamanetwork.com/journals/jama/article-abstract/2804092 
3. Fazio J, Heras A, Stein E, et al. Melanoma Antigen Recognized by T Cells With Blue Chromogen Improves Identification of Melanocytes From Background Melanized Keratinocytes on Frozen Sections. Dermatol Surg 2023;49:709-711.

Abstract

BACKGROUND

Nail apparatus melanoma is a malignant tumor with a high incidence in Chinese melanoma patients. Slow Mohs micrographic surgery is an emerging technique for treating nail apparatus melanoma in situ (NAMIS).

OBJECTIVE

This study evaluated the efficacy and safety of slow Mohs micrographic surgery for treating NAMIS.

METHODS

Patients were enrolled in this retrospective study and treated in a single center from October 1, 2016, to June 30, 2022. Each patient underwent standard slow Mohs micrographic surgery, and follow-up was regularly conducted at clinics.

RESULTS

Ten patients were enrolled in the study. Two patients underwent one Mohs stage, seven underwent two Mohs stages, and one underwent seven Mohs stages. The resection margin ranged from 5 to 25 mm. No severe complications were reported in the treatment, and recurrence of NAMIS was not observed during the follow-up period.

CONCLUSION

Slow Mohs micrographic surgery is a valuable surgical method to treat NAMIS that preserves digit function and can be well tolerated by patients.

International Journal of Dermatology

Slow Mohs micrographic surgery for nail apparatus melanoma in situ

Int. J. Dermatol 2023 Jun 23;[EPub Ahead of Print], S Zhang, Y Wang, K Fang, Q Jia, H Zhang, T Qu