Previously unreported X-ray findings associated with distal toe pain in children.

While children undergo skeletal maturation, it is difficult to distinguish between normal variants and abnormalities of the epiphysis and acrophysis on radiological images. Abnormalities in the epiphysis and acrophysis of the toe phalanx have not been reported yet. Here, we describe a series of abnormalities in the epiphysis and acrophysis of the fourth and fifth toe phalanges, including an investigation of their pathogenesis. We evaluated patients suspected of having bone tumors at a local orthopedic clinic because of abnormal findings of the toe phalanx between the distal and middle phalanx on plain radiographs. The site of the lesion, duration of pain until the hospital visit, history of trauma and sports, treatment, and clinical course were investigated. A total of seven patients (five boys and two girls) with a mean age of 10 years (range 9-16) were included. In all cases, a circular erosive radiolucent image was present between the distal and middle phalanx. In two cases, the fourth toe was affected, and in five cases, the fifth toe was affected. Six patients showed improvements with conservative treatment using shoe insoles. In one case, surgical treatment was performed for persistent pain. Histological examination of the fibrous tissue collected from the circular erosive radiolucent area revealed normal bone and slightly degenerated hyaline cartilage. This is the first report on the abnormalities of the epiphysis and acrophysis of the toe phalanx, which is termed as Shintaniwakino disease. A better understanding of this disease may aid in the avoidance of unnecessary treatment. Level of Evidence: IV.