Fibromatosis of the flexor pollicus longus tendon

An unusual case of fibromatosis of the dominant left flexor pollicus longus (FPL) in a thirteen year old schoolboy. Initially presenting with pain in the thenar eminence and difficulty flexing the metacarpal phalangeal joint (MPJ), other symptoms include locking, triggering and difficulty writing. MRI showed a 4cm segment of thickened abnormal tendon. Intra-operatively three 1cm nodules were excised from the FPL while preserving the tendon. Histopathology reported the nodules as fibromatosis.A literature search revealed that this has not previously been reported although symptomatic tendon sheath fibromas have. Our patient achieved a good result following surgical intervention and the two year review has shown no complications.