case_images: PMC9052806_01
case_images: The left index finger (a, b) showed diffuse soft tissue swelling without
  local heat, redness, or tenderness (arrow).
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case_images: The left index finger showed diffuse soft tissue swelling without local heat and redness, or tenderness (Figure 1(a)). The circumferential diameter of the left index finger at the base of the finger was 6.8 cm, whereas that of the unaffected index finger was 5.8 cm (Figure 1(b)).
case_images: Radiographs of the left index (a, b) showed swelling of soft tissue without
  bone involvement.
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case_images: Radiographs of the left index finger showed swelling of soft tissue without bone involvement (Figure 2(a) and (b)).
case_images: Preoperative magnetic resonance showed a defined lesion (arrow) in the
  synovial sheath of the flexor tendons with iso-signal intensity to muscle on
  a T1-weighted sagittal image (a), and with high signal intensity to muscle
  on T2-weighted sagittal image (b). It was enhanced in T1-weighted fat
  suppression with gadolinium enhancement (c).
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case_images: Preoperative magnetic resonance showed the defined lesion in the synovial sheath of the flexor tendons, which had iso-signal intensity to muscle on a T1-weighted sagittal image (Figure 3(a)) and which had high signal intensity to muscle on a T2-weighted sagittal image (Figure 3(b)). It was enhanced in T1-weighted fat suppression with gadolinium enhancement (Figure 3(c)).
case_images: Surgical findings were significant of extensive synovitis (arrow) affecting
  both superficial and deep flexor tendons (a, b). Complete flexor
  tenosynovectomy was performed (c).
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case_images: The tenosynovium was found in the flexor tendon sheath from the level of the DIP joint to the distal palmar crease (Figure 4(a) and (b)). After the flexor tendon sheath was released, complete flexor tenosynovectomy was performed (Figure 4(c)).
case_images: Resected tissue by hematoxylin-eosin staining showing, mainly, proliferation
  of synoviocytes and plasma cell and lymphocyte infiltration: (a) low
  magnification and (b) high magnification.
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case_images: Histopathological evaluation of the resected tissue by hematoxylin-eosin staining showed mainly proliferation of synoviocytes and plasma cell and lymphocyte infiltration: Figure 5(a), low magnification; and Figure 5(b), high magnification.
case_images: (a) After 8 months of operation, no sign of recurrence had been identified.
  (b) The patient has recovered the capability of full-range motion of the
  affected digit.
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case_images: The patient has recovered full range of motion of the affected digits (Figure 6(a) and (b)).