Congenital absence of flexor pollicis longus without hypoplasia of the thenar muscles.

We report a rare case of absence of the flexor pollicis longus in a hypoplastic right thumb, without hypoplasia of the thenar muscles in an 11-year-old girl, who was treated by transfer of flexor digitorum superficialis of the ring finger to the thumb to achieve active flexion at the interphalangeal joint of the thumb.