The use of immunohistochemistry in the evaluation of the nail matrix in biopsies of ingrown toenails.

The success of surgical approaches to ingrown toenails depends on the extraction (either partial or total) of the nail matrix. The identification of the nail matrix in specimens taken from ingrown toenails is not always easy because of the fragmentation of the biopsies, difficulties in matrix orientations and the heavy inflammatory infiltrate. In biopsies taken from polydactyly surgeries, the matrix shows a peculiar pattern of expression of the CD10 and CD34 markers that differs from the one shown by the lateral nail fold. We investigated whether such a pattern was also found in biopsies from ingrown toenails, which can be greatly distorted through inflammation and fibrosis. We examined 15 biopsies from cases of ingrown toenails at different clinical stages. We performed routine Hematoxylin-Eosin studies, as well as immunohistochemical studies with CD10, CD34, HMB-45 and Melan-A. The morphologic changes in all cases were typical of those found in ingrown toenails and their intensities correlated with the clinical stages. Matrical keratinization was identified in all of the biopsies. Morphologic features that are compatible with the lateral nail fold were also seen in seven of the 15 biopsies. In five cases, an intermediate area of transition between matrix and lateral nail folds was heavily distorted by inflammatory changes. Melanocytic markers showed scattered intra-epidermal cells in all but one case. HMB-45 and Melan-A were equally good in demonstrating the melanocytic population. We concluded that the expression of CD10 and CD34 in cases of ingrown toenails is preserved and it follows the pattern described in nails from polydactyly. Therefore, both markers can be useful in fragmented specimens taken from surgeries for ingrown toenails, in order to confirm the removal of the nail matrix.