Phocomelia Re-Examined Using the CoULD Registry

Phocomelia is an intercalary segmental dysplasia of the upper limb, a distinct entity from longitudinal deficiencies. Nearly 20 years ago, more severely dysplastic limbs initially thought to be phocomelia were able to be reclassified as more severe forms of longitudinal dysplasia. This study sought to evaluate current phocomelia cases to identify if these represented true phocomelia.

Using the Congenital Upper Limb Differences Registry, all cases of phocomelia were evaluated to consider the phocomelia diagnosis. Twenty patients were included for assessment, in whom 23 extremities were classified as phocomelia. Three extremities had clavicle dysplasia and were not included in the final assessment. The radiographs, clinical images, and medical histories were examined to assess the limb diagnosis. Patients with Type V ulnar or radial longitudinal dysplasia were also evaluated to ensure no possible mis-classification.

All extremities could be reclassified as either ulnar longitudinal dysplasia (ULD) or radial longitudinal dysplasia (RLD), with 18 ULD and 5 RLD. No true case of phocomelia was identified in this cohort. Extremities with more severe dysplasia than type V classifications were able to be classified using associated syndromes, contralateral limb diagnosis, lower limb involvement, bony morphology, and hand/digit patterning.

True phocomelia is rare and most severely dysplastic limbs can be classified as ULD or RLD with specific guidelines, which is critical in clinical care, in assessing for additional medical comorbidities, and for family counseling.

Patients with presumed diagnosis of phocomelia should be critically reassessed, using other patient characteristics (syndrome diagnosis, lower limb involvement, etc.), for RLD or ULD to ensure necessary medical testing is completed.