Trigger finger at the wrist caused by an intramuscular lipoma within the carpal tunnel: A case report

Figure 2 Entrapment symptoms appeared within the carpal tunnel during finger flexion and extension. A: The tumor involved the flexor digitorum superficialis of the index finger in the carpal tunnel; B: In the passive flexion position of the index finger, the mass moved proximally with the flexor digitorum superficialis; C and D: In the extension position of the index finger, the mass moved with the flexor digitorum superficialis and extended into the carpal tunnel. In the overextension position, the mass further moved into the carpal tunnel, extruding the common flexor tendon sheath and the median nerve.