Limited Flexion of the Middle Finger Due to a Degenerative Partial Flexor Tendon Rupture Mimicking a Soft Tissue Tumor.

Atraumatic subcutaneous rupture of the finger flexor tendon of the hand and forearm is rare. Most sites of closed and subcutaneous ruptures of the finger flexor tendon are the tendon-bone insertion and musculotendinous junction, and an intratendinous lesion is unusual. We report the case of a 76-year-old female who presented to our department with a one-month history of a soft tissue mass and limited flexion of the left middle finger without trauma. Preoperative magnetic resonance imaging revealed a soft tissue mass that caused limited finger flexion. Intraoperative findings showed an intratendinous rupture of the flexor digitorum profundus tendon at the middle phalanx; the lesion was resected to obtain smooth grinding of the tendon. One year postoperatively, the soft tissue mass and limited flexion of the finger resolved without recurrence.