Safety and efficacy of the keystone and rhomboid flaps for immediate reconstruction after wide local excision of non-head and neck melanomas

BACKGROUND: After wide local excision of cutaneous melanoma, large defects not amenable to simple primary closure are often covered with skin grafts. We report our experience using the rhomboid and keystone flaps to immediately close large axial and extremity wounds after potentially curative surgery for non-head and neck melanomas. METHODS: Between January 2011 and September 2016, demographic, operative, pathologic, and outcome data were prospectively collected on 60 patients who underwent wide local excision of melanoma followed by immediate flap reconstruction. Flaps were of either rhomboid or keystone type. Chi-square analysis was used to compare relationships between factors. RESULTS: All procedures were done by the senior author and as outpatient surgery. No patient required a surgical drain unless they were undergoing concomitant radical regional node dissection. Flap separation (arbitrarily defined as a >5-mm dehiscence of the suture line) occurred in 16/61 patients (26 %). No patient had flap loss. The risk of flap morbidity was significantly higher if the primary tumor was on the distal extremity—10 of 24 patients (42 %), all with keystone flaps—than if it was on the trunk or the proximal extremity (6/37 patients, 16 %), p = 0.04. There were no margins positive for either invasive or in situ melanoma in the entire cohort. CONCLUSIONS: Simple transposition flaps can successfully cover large defects after melanoma excision without the need for skin grafting. Keystone flaps in the distal extremity are more prone to separation, but this is minor and does not result in flap loss. There is minimal risk of a positive margin requiring flap takedown and a second re-excision.