Delayed Diagnosis of Retronychia: How Ultrasound Can Nail the Diagnosis in Clinically Subtle Patients.

A 47-year-old man presented to the dermatologic surgery clinic with a 7-month history of a painful, swollen left great toe after minor trauma. Intermittently, the toe became exquisitely tender such that even weight of a blanket exacerbated pain. The patient initially presented to primary care with purulence and pain, but the culture of expressed purulence revealed normal flora. Condition of the patient did not improve despite evaluation by several medical specialists and multiple rounds of topical antifungal and steroid creams, vinegar soaks, and oral antibiotics.