Onychomatricoma: genome-wide analyses of a rare nail matrix tumor

Background: Onychomatricoma (OM) is a rare benign tumor of the nail matrix in which genome-wide analyses have never been performed. It is clinically characterized by an increased transversal curvature of the nail plate, a longitudinal yellowish discoloration, and splinter hemorrhages. Once the nail plate has been removed, fingerlike fibrokeratogenous projections appear through the proximal nailfold. Histologically, it is a fibroepithelial tumor with well-established features. In this article, a comprehensive review of this tumor is made.

Objective: We performed a genome-wide analysis of an OM, in an attempt to shed light on the mechanisms underlying its development.

Methods: We report a 36-year-old man who was given a diagnosis of OM involving his fourth right toenail. To investigate molecular genetic alterations, we carried out two approaches, fluorescent in situ hybridization and array-based comparative genomic hybridization, in our patient.

Results: Genomic testing of OM showed 34 genomic alterations, with most of the genomic losses being on chromosome 11. Array-based comparative genomic hybridization showed the deletion of 11p15.4, which harbors STIM-1, 11q14.2 (RP-11 292E14), which harbors the Cathepsin C gene, 11q14 (RP11-281F10-RP11-265F24), and 11q21 (RP11-203F8 and RP11 183A22).

Limitations: This work is an initial approach to a genome-wide study of this tumor. Further studies (with more cases) must be conducted to pinpoint possible candidate genes for the development of OM.

Conclusions: Array-based comparative genomic hybridization showed important genomic alterations in OM, especially genomic losses. Most genomic losses affected the chromosome 11 in our patient. The STIM-1 and the Cathepsin C genes might play a role in the development of OM.