Congenital absence of the 5th digital ray and its proximal segmental structures.

Limb reduction anomalies involving digits or parts of limbs are not uncommon. Most cases take the form of terminal transverse absence defects involving hypoplasia or aplasia of all structures distal to a particular level on a limb with relative preservation of the more proximal tissues. Longitudinal absence defects are a more rare form of limb reduction anomalies. Structures within one or more digital rays are typically involved. More proximal segmental tissues may also be affected with the most serious cases resulting in absence of the radius or ulna. We report a case of isolated, longitudinal absence of the 5th finger and its corresponding proximal segmental structures in a newborn infant. The embryology of limb development and possible etiologies for skeletal absence defects are summarized.