Polydactyly of a biphalangeal thumb

A rare non-syndromic limb malformation characterized by the duplication of one or more skeletal components of a biphalangeal thumb and/or hallux. Hands are preferentially affected (in bilateral), and the right hand is more commonly involved than the left. Hallux duplication may present concomitantly to, or independently of thumb polydactyly and is predominantly unilateral right.