case_images: PMC10746917_01
case_images: Unique skin findings upon finger locking in the A3 pulley trigger finger. (a, b) The volar side of the right middle finger.
  A round and hard mass measuring 2 mm is palpated around the proximal interphalangeal (PIP) crease (A, circle). During locking
  in finger extension, a V-shaped skin depression is seen (B, arrowheads). (c, d) The lateral side of the right middle finger. Linear
  skin depressions are observed on the bilateral sides of the base of the middle finger, when it is locked during finger extension
  (D, arrowheads).
case_images: JDRS-2024-35-1-249-253-F1.jpg
case_images: PMC10746917_01_JDRS-2024-35-1-249-253-F1.jpg
case_images: F1
case_images: Skin findings showed a V-shaped skin depression on the PIP crease during finger locking (Figure 1a, b, Video 1) and linear skin depressions bilaterally on the sides of the proximal phalange (Figure 1c, d) during finger locking.
case_images: Osteochondroma of the middle phalanx. (a) Radiography shows a bone tumor protruding from the base of the middle
  phalanx (arrowhead). (b, c) Computed tomography. Sagittal (b), axial (c), and 3-dimensional image of the bone tumor (arrowhead).
  The cortex and medulla of the tumor are in continuity with the underlying bone.
case_images: JDRS-2024-35-1-249-253-F2.jpg
case_images: PMC10746917_01_JDRS-2024-35-1-249-253-F2.jpg
case_images: F2
case_images: Radiography revealed a bone tumor protruding from the volar side of the base of the middle phalanx (Figure 2a). Computed tomography showed that the cortex and medulla of the tumor were in continuity with the underlying bone (Figure 2b-d).
case_images: The A3 pulley tethered by the bone tumor during finger extension. (a) A Bruner incision was made around the PIP
  crease. The C1 pulley was torn, and the apex of the tumor was exposed just beneath the skin. (b) A magnified image of the boxed
  area in A. The apex of the tumor (arrowhead) interfered with the A3 pulley (arrow) during finger extension. *: Flexor digitorum
  profundus tendon. (c) After tumor resection. The tumor penetrates the radial side of the FDS tendon (arrow). *: Flexor digitorum
  profundus tendon.
  PIP: Proximal interphalangeal; FDS: Flexor digitorum superficialis.
case_images: JDRS-2024-35-1-249-253-F3.jpg
case_images: PMC10746917_01_JDRS-2024-35-1-249-253-F3.jpg
case_images: F3
case_images: A Bruner incision was made around the PIP crease of the middle finger, and intraoperative findings revealed that the C1 pulley was torn and the apex of the tumor was exposed beneath the skin (Figure 3a). The apex of the tumor interfered with the A3 pulley during finger extension (Figure 3b). The tendon was dissected from the base of the tumor, and the tumor was ultimately resected (Figure 3c).