We present an unusual case of polydactyly of the thumb. The patient, d
espite having a fully developed nail bed, had a duplication at the met
acarpophalangeal level consisting of a single bony phalanx. The Wassel
classification of polydactyly, which is the most commonly cited class
ification scheme, does not include this particular anomaly. In additio
n, there has been no reference to this type of polydactyly in the lite
rature.