Heterotopic respiratory mucosa as a potential source of ectopic Sonic hedgehog (SHH) in the development of complex radial polydactyly and ulnar dimelia.

We report eight cases of complex radial polydactyly and/or ulnar dimelia each with a fistulous lesion of heterotopic respiratory mucosa in radial-anterior skin ranging from shoulder to wrist. Although speculative, the coincidence of these rare conditions suggests a mechanistic relationship.