Deep Margins Melanoma: How Deep Is Deep Enough?

Background: Wide excision (WE) to muscular fascia for invasive melanoma is common practice but excision to subcutaneous tissue may be adequate. We evaluated practice patterns regarding depth of biopsy and excision as well as risks for recurrence.

Methods: Retrospective review of patients with pT1-4 melanoma (cN0) treated with WE at a single institution was performed. Patient factors were evaluated. Biopsy and excision techniques were compared to pathology and reviewed for recurrence.

Results: 385 patients from 2006 to 2020 were included. Lesions were on the extremity (n = 189), head/neck (n = 48), trunk (n = 148). Biopsy techniques included shave (n = 330), excisional (n = 36), punch (n = 10), incisional (n = 9). Deep biopsy margins were positive for IM/melanoma in situ in 139 patients. WE specimens were taken to muscular fascia (n = 218) or mid/deep fat (n = 144). 51 patients had recurrent disease or a new primary lesion: locoregional (n = 31), distant (3), or new lesions (n = 17).

Discussion: Patient characteristics associated with recurrence include older age and female gender. Tumor characteristics associated with recurrence include lesions located on the trunk, superficial spreading melanoma, ulceration, perineural invasion, and clinical T and P stage. Patients that recurred were more likely to have WE taken to or including muscular fascia. Biopsy type, deep margin on biopsy, and depth of dissection was not associated with recurrence.