Risk factors, clinical variants and therapeutic outcome of retronychia: a retrospective study of 18 patients.

Retronychia is a form of post-traumatic ingrowing nail disease that involves proximal nail plate embedding into the proximal nail fold, with multiple generations of nail plate beneath the proximal nail. This disease is probably underdiagnosed because of incomplete clinical forms. The aim of this study was to report clinical and aetiological variants of retronychia and to evaluate their therapeutic outcome. A retrospective review was performed on 18 patients who were seen in our institution between 2007 and 2013. The diagnostic criteria for retronychia were paronychia and interruption of nail growth. A female predominance (83.3%) was reported. Various precipitating factors were found, including traumatisms in 10 patients (55%), pregnancy and postpartum period in two patients (11%), and compartment syndrome in one patient (5%). The mean duration of paronychia was eight months (15 days to four years). The fingers most affected were the great toes. Retronychia occurred bilaterally in five cases (27%) and unilaterally in one case (61%). The commonest signs were, in decreasing order, xanthonychia (yellow discolouration of nail plate), longitudinal nail over-curvature, swelling of proximal nail fold, elevation of the proximal nail plate, granulation tissue, subungual hyperkeratosis, superficial leuconychia, distal onycholysis, subungueal haemorrhage, and Beau's lines. Most of the cases improved after proximal nail plate avulsion. Recurrence occurred in three cases (16.6%). In our opinion, ischaemic damage is the main cause of retronychia. Evaluation of clinical variants is mandatory to propose appropriate treatment. The limitations of this study include the retrospective design.