Immunohistochemical identification of nail matrix melanocytes

No previous studies have been conducted to determine the normal number of nail matrix melanocytes in Latin American individuals. The objective of this work was to determine the number of melanocytes per linear millimetre present in the nail matrix and the nail bed in samples obtained from Colombian individuals.

Twenty-six unilateral biopsies were taken from 19 cadavers subjected to clinical and medico-legal autopsies. These biopsy samples were processed with conventional histotechnology and immunohistochemistry (IHC) with anti-HMB-45 and anti-MiTF. Three sets of photographs (HE, HMB-45 and MiTF) were taken of each biopsy sample and independently assessed by three pathologists. Each observer counted the number of melanocytes present in 1 linear mm of the nail matrix or bed.

We found an average of 4.6 melanocytes x linear mm with H & E staining, 9.8 with HMB-45 and 12.4 with MiTF.

The use of IHC significantly increases and facilitates the identification of melanocytes in unilateral biopsies. Our IHC counts exceed the averages found in the literature. This finding warrants new studies to verify whether the Colombian population presents higher numbers of melanocytes in the nail matrix than other populations or whether the observed increase is a result of the use of MiTF.