Abstract

Onychomatricoma is a rare benign nail unit fibroepithelial tumor, first identified by Baran and Kint in 1992. Typically the tumor’s nail plat shows localized or diffuse thickening, transverse overcurvature and xanthonychia. Onychomycosis is known to affect onychomatricomas occasionally.  However, this concomitant infection has not been reported to cause a concomitant chromonychia aside from the usual color of the tumor.  Herein, we report a case of onychomatricoma that had a delayed diagnosis and a unique pigmentation to it, which was ultimately determined to be secondary to concomitant pigmented onychomycosis. A 50-year old female presented with 10 years of thickening and discoloration of the left middle fingernail. She failed therapy with several months of oral and topical antifungal agents. Physical examination demonstrated the left middle fingernail showed longitudinal xantholeukopachyonychia with bluish pigmentation. Nail clipping histopathology showed honeycomb-like cavities with encased pigmented fungal elements.  Complete excision demonstrated typical histopathologic features of an onychomatricoma, along with extensive pigmented fungi.  The blue color found within this onychomatricoma is thought to be caused by a combination of the presence of pigmented fungi and the tyndal1 effect.