Duplicated thumb with enormous soft-tissue oedema - pacifier type of thumb duplication.

Here we presented the first case of pacifier type thumb duplication. A newborn Japanese girl with no family history had a duplicated thumb on her left hand. The duplicated thumb showed a very large, oedematous soft-tissue nubbin in its appearance and was resected on the fifth day after birth. X-ray showed hypoplastic phalanx bone, suggesting type II polydactyly. Histology of the resected thumb showed enormous oedema in its connective tissue with cartilaginous and neural elements. This case was quite similar to literary reported cases of pacifier polydactyly in post-axial polydactyly, and its pathological condition seemed to be distinctly different from floating type or rudimentary type thumb duplication. We considered this type of thumb duplication as pacifier type thumb duplication, rather than floating or rudimentary type, in order to understand its underlying pathophysiology and to avoid confusion in further discussions.