The Utility of De-epithelialization in Subcutaneous Skin Flap Transposition

To address soft tissue volume deficiencies following surgery or injury, plastic surgeons implant de-epithelialized flaps subcutaneously. During this procedure, residual epidermal components and skin appendages may inadvertently be implanted, potentially leading to postoperative complications. However, such occurrences are rare in clinical practice. To date, no studies have examined the long-term changes in subcutaneously transposed skin flaps.

De-epithelialized and non-de-epithelialized flaps were implanted subcutaneously in rat models. Pathological analyses, Western blotting, and quantitative real-time polymerase chain reaction were performed to evaluate temporal changes.

In all cases of non-de-epithelialized flap implantation, subcutaneous masses were palpable at all time points. Pathological and molecular analyses revealed the formation of a single epidermal cyst at each site throughout the study period, with no significant changes in keratin 5 expression, a marker of the basal epidermal layer. In contrast, in de-epithelialized flap sites, subcutaneous masses observed at 1 month postoperatively gradually regressed over time. Clusters of small cysts that initially formed at 1 month postoperatively disappeared over time, coinciding with a reduction in keratin 5 expression. Furthermore, regardless of epithelialization status, the development of body hairs from subcutaneously implanted follicles progressively diminished.

These findings suggest that in non-de-epithelialized flaps, residual epidermis persists and continues to differentiate, potentially leading to complications. In contrast, in de-epithelialized flaps, remaining skin appendages and epithelial components gradually regress, thereby reducing the risk of complications. The results underscore the clinical usage of de-epithelialization in subcutaneous skin flap transplantation.