Background
Skin biopsies are critical for diagnosis and treatment of rejection after facial allotransplantation (FAT). Many facial allografts provide only limited skin area and frequent biopsies may compromise aesthetic outcome. In these cases, sentinel flaps (SFs), recovered as a free fasciocutanous radial forearm flap, have been employed for remote site rejection monitoring. These flaps maintain their axial blood supply similar to facial allografts (FA). The correlation between FA and SF in cases of rejection is presented.
Methods
We analyzed our experience with employment of 4 SFs. Biopsies from both FA and SF were taken using a standard 4mm punch biopsy from the most erythematous area of the allograft. Rejection was evaluated and the results compared for each time point. The SFs where used as functional flap whenever possible (e.g. to release a contracture).
Results
The results show a reliable correlation between biopsies taken from the FA and SF. During severe rejection episodes in 100% of the biopsy pairs both sites displayed a similar grade of rejection. In one case the clinical findings suggested rejection in the FA but were unraveled as Rosacea, since clinically there was no rejection displayed in the SF. In 3 of the 4 patients the location of the flap inset was selected for a release of hand first web space contracture or coverage of unstable scars.
Discussion
The utilization of a SF can prevent impairment of aesthetic outcomes in FAT. SF showes a reliable correlation to the FA in cases of severe rejection and therefore provides a valuable tool for rejection monitoring in FAT. Moreover, it can be used to discern clinical signs of rejection by helping to differentiate from facial erythematous conditions related to other causes such as Rosacea. If the FA contains limited skin surface or cannot be used for biopsies due to presence of active opportunistic infections triggered by the immunosuppression, the SF is especially valuable as biopsy site to monitor rejection in the FA. The SF can moreover be employed as functional flap, if applicable.