Unique inflammatory features noted in intraorally transferred skin flaps: correlation with Candida albicans infection

The purpose of this study was to evaluate how well intraorally transferred skin flaps endure their new surroundings.

Biopsy specimens were taken from 20 patients who had undergone microsurgical reconstruction and as pretransferred skin from 5 of these patients at the time of surgery. The study used immunohistochemistry for immunocompetent cells, differentiation markers for the epidermis and desmosomal proteins, and immunoelectron microscopy for desmosomal protein, in addition to routine histologic examination, including Sudan IV, periodic acid Schiff, and Grocott stains. We also measured the thickness of the epidermis and stratum corneum. Oral swabs from the skin flaps were examined for the presence of yeasts, particularly Candida albicans, by means of a culture method.

According to the results of periodic acid-Schiff and Grocott staining, 20 cases were divided into 2 groups: fungal element-positive cases (n = 15) and fungal element-negative cases (n = 5). All swabs from the former were positive for Candida albicans. In these fungus-positive cases, histopathologic evaluation revealed marked diminution of stratum corneum and pronounced epidermal hyperplasia. Immunohistochemistry demonstrated the dermal infiltration of numerous immunocompetent cells-CD4+, CD8+, CD20+, CD68+, neutrophil elastase+, and HLA-DR+ cells-and the scarce infiltration of IgA+ and IgG+ cells. There were scattered CD1a+, CD4+, CD8+, and HLA-DR+ cells and elastase+ neutrophils in the epidermis. Expression of cytokeratin subtypes (10, 14, 16, and 19), involucrin, and tenascin showed the characteristic features of epidermal proliferation. Enumeration of Ki-67+ keratinocytes showed an increase, indicating epidermal proliferation. Expression of desmoglein 1 and desmocollin 1 in the epidermal keratinocytes was decreased in comparison with that in the pretransferred skin. Immunoelectron microscopy for desmoglein 1 confirmed the reduced immunoreactive deposits along the desmosomal plaques. In the fungus-negative cases, all such changes were a great deal milder.

Taken together, our results demonstrate that most intraorally transferred flaps are affected by an inflammatory process that is induced by the influence of the wet oral environment. They present psoriasiform tissue reactions characterized by epidermal hyperproliferation that are mostly due to Candida albicans infection.