Retronychia is an infrequent disease in children and adolescents that is associated with the combination of 3 factors: disruption of the nail plate’s growth, misalignment of the nail matrix and the nail plate and poor adhesion of the old plate to the nail bed.1,2 The pressure of the nail against the proximal nail fold causes pain and inflammation, and the repeated disruption of the growth of the nail matrix leads to the stacking of successively generated nail plates. It is usually triggered by trauma or local injury, although it can also develop spontaenously.3 It is diagnosed based on the clinical findings, although ultrasound imaging can be used as a non-invasive confirmatory test.2,3 The definitive treatment is surgical, through proximal avulsion of the nail, removing the old nail plate and the underlying ingrown plates.3
We describe a series of 4 patients that received a diagnosis of retronychia after developing pain and erythema in the first toe with proximal rising of the nail, confirmed in the ultrasound examination by the visualization of multiple nail plates, among other findings (Fig. 1). After initial treatment with empiric antibiotherapy, all patients underwent definitive treatment with surgery, with total proximal avulsion of the nail (Fig. 2), which achieved a cure.
Comparison of ultrasound appearance of the first two toes. Longitudinal (A) and transversal (B) views of the healthy nail compared to the longitudinal (C) and transversal (D) nail involved in retronychia. We can see two superimposed nail plates (*), characteristic of retronychia, with a hypoechoic space in between (arrow).
