Mohs micrographic surgery (MMS) to remove digital melanomas of less than 2 mm Breslow thickness spared patients from amputation without undermining survival, according to a single-center retrospective study published in Dermatologic Surgery.
The overall recurrence rate was 8%, and there were no recurrences with use of the MART-1 (melanoma antigen recognized by T-cells 1 staining) immunostain, said Dr. Vitaly Terushkin of the Zitelli and Brodland Skin Cancer Center in Pittsburgh and his associates. “The use of MART-1 has revolutionized the value of MMS,” the researchers said, while cautioning that the sample size was too small to draw reliable conclusions about thicker tumors.
Digital melanoma historically eluded diagnosis until it was advanced and was treated with amputation. Amputation and wide local excision remain common, and particularly erode function and balance when the tumor involves the thumb or big toe, the researchers noted. In 35 years at their center, 62 patients underwent MMS for digital melanoma, two-thirds of which involved the nail unit. About 92% of tumors were primary, 8% were recurrent, 53% involved the fingers, and 47% involved the toes. About half of patients were women, and the average age at treatment was about 63 years (Dermatol Surg. 2016;42:83-93).
Nearly 97% of patients avoided amputation over an average of 6.5 years of follow-up, the investigators reported. Five-year and 10-year local recurrence-free survival rates for the primary melanomas were about 92% and 83%, respectively. Of the five local recurrences, three were salvaged with additional MMS and two were treated with an amputation; all five recurrences involved the nail unit. Failing to remove the entire nail unit apparatus probably led to false-negative MMS layers and subsequent recurrence in at least two cases, they pointed out.
This is only the fifth published study to describe the treatment of digital melanoma with MMS, according to Dr. Terushkin and his associates. Although the study lacked a comparison group, it suggested that MART-1 improved outcomes and that most recurrences could be retreated with MMS without amputation or negative effects on survival. These findings will hopefully help inform future melanoma guidelines, said the researchers.
The investigators reported no funding sources and had no disclosures.