Utility of Sentinel Flaps in Assessing Facial Allograft Rejection

Background: Skin biopsies are critical for histologic evaluation of rejection and proper treatment after facial allotransplantation. Many facial allografts provide only limited skin area, and frequent biopsies may also compromise aesthetic outcome. Sentinel flaps, recovered as free fasciocutaneous radial forearm flaps, have been used for remote-site rejection monitoring. They maintain their axial blood supply, similar to facial allografts. The correlation between facial allografts and sentinel flaps in cases of rejection is presented. Methods: The authors analyzed the experience of the Boston team’s use of four sentinel flaps. Rejection was evaluated and results were compared for each time point. Sentinel flaps were used as functional flaps whenever possible. Results: Results showed a reliable correlation between biopsy specimens taken from the facial allograft and sentinel flaps. During severe rejection episodes in 100 percent of biopsy pairs, both sites displayed a similar grade of rejection. In one case, clinical findings suggested rejection in the facial allograft but were unraveled as rosacea, because clinically there was no rejection displayed in the sentinel flap. Conclusions: The sentinel flap shows a reliable correlation to the facial allograft in cases of severe rejection, therefore providing a valuable tool for rejection monitoring in facial allotransplantation. Advantages of using these flaps include the avoidance of further surgical procedures to the primary vascularized composite allotransplant, additional use of the sentinel flap to repair damaged nonfacial sites, and its utility as both a clinical and histopathologic barometer of rejection and predictor of the potential existence of facial dermatitis unrelated to rejection. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.