Retronychia: clinical diagnosis and surgical treatment.

To cite: Campos MA, Santos A. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2016218758 DESCRIPTION Retronychia is the term used for proximal ingrowth of the nail and was first described by De Berker and Rendall in 1999. It frequently affects women (∼82%), and the great toes are the most common location. The most frequent trigger is (micro) trauma. With trauma the nail plate separates completely from the matrix, a new plate grows under the old plate, pushes it upwards and is buried into the ventral aspect of the proximal nail fold (PNF), causing inflammation. This condition is rarely diagnosed and in 70% of the cases patients have been inadequately treated with oral antibiotics and antifungals. We report the case of a 14-year-old girl who was referred to our outpatient clinic with oedema, erythema and pain of the proximal nail fold of the right hallux (figure 1A). This condition had been present for 3 months and was resistant to topical and oral antibiotics. There was no family history of melanoma. The patient ran twice a week. Given this clinical presentation, we considered retronychia as the most probable diagnosis. We performed surgical avulsion of the nail plate that demonstrated thickening of the proximal plate and the presence of two layers of nails (figure 1B, C). Histological examination of the nail excluded the presence of malignancy. After 4 months of follow-up, 40% of the nail had regrown with slight thickening and yellowing but with no sign of recurrence (figure 1D). We explained the possibility of permanent dystrophy and yellowing of the nail to the parents.