Presentation
Painful lump in the dorsum of the left hand.
Patient Data
Ultrasound demonstrates an ellipsoid soft tissue mass with a muscle-like echo texture within the fourth extensor compartment, between the extensor tendons of the second and third digits.
MRI confirmed an ellipsoid mass between the second and third extensor tendon digits, which is isointense and hyperintense in DP FATSAT compared to the normal muscles, with minimal enhancement, suggestive of extensor digitorum brevis manus with inflammation.
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blue: muscle-like echo texture soft tissue masse (accessory muscle).
Case Discussion
This case demonstrates an extensor digitorum brevis manus muscle (EDBM), which is a normal variant. The pain is a consequence of muscle hypertrophy and inflammation.