Congenital Upper Extremity Anomalies Misdiagnosed as Ulnar Longitudinal Deficiency.

Background: Patients with a congenital hand plate or upper limb anomaly, a dysplastic ulna, or a syndrome may present with morphologic forms commonly misdiagnosed as ulnar longitudinal deficiency (ULD). Methods: Patients who had been misdiagnosed with ULD over the past 35 years were identified from the hospital database. Twenty-six patients with photographs and/or conventional radiographs that could be adequately reproduced were enrolled in the study. Results: In 16 unilateral cases, the final diagnosis changed to symbrachydactyly (6 cases), Poland syndrome (3 cases), transverse deficiency (1 case), radial longitudinal deficiency (2 cases), and congenital pseudarthrosis of the ulna with osteolysis in patients with neurofibromatosis type 1 (4 cases). In 10 bilateral cases, the final diagnosis changed to constriction ring sequence (3 cases), brachydactyly (6 cases), and congenital bilateral negative ulnar variance in a patient with central metacarpal medullary stenosis. This research presents the findings of the 7 most illustrative cases and focuses on their differential diagnosis. Additionally, the literature review summarizes the most common congenital anomalies included in the differential diagnosis of ULD, presenting their clinical and/or radiographic features as detected in patients referred to our service. Conclusions: A detailed evaluation of patients with even simple unilateral congenital hand or upper limb anomalies is invaluable to the diagnostic investigation. The treating pediatrician, clinician, or surgeon should also be sufficiently familiar with the clinical and radiographic features of congenital anomalies and the long list of syndrome-related deficiencies that the differential diagnostic process of ULD includes. Missed or misinterpreted findings in patients with congenital hand or upper limb anomalies, usually recorded after single diagnosis documentation, may result in a misdiagnosis of ULD and delayed detection of associated congenital, medical, or syndromal disorders.