Diagnostic Evidence Depicting Palmaris Longus Origin Reversal: Ultrasound and MRI Evaluation

Abstract

Introduction: The palmaris longus (PL) is very prone to anatomical variance. It may exhibit agenesis, reversal, and duplication. The reversal variant presents with the PL tendinous aspect proximally and the muscle belly distally. It is an important finding, and it is important to consider when making a differential diagnosis. This is the only reported case of a left distal forearm PL muscle variant with ultrasound and magnetic resonance imaging (MRI) in a Caucasian adult male. Case Report: A 28-year-old Caucasian male presented to the clinic with an abnormal ultrasound finding of a left wrist mass. The patient was instructed to get an MRI, which demonstrated and further confirmed the reversed PL muscle. Conclusion: Although rare, anatomic muscle variance may occur in many places of the body leading to symptoms that need attention. These variants should be considered in orthopedic differential diagnosis and ruled out appropriately with proper diagnostic techniques. By making the correct diagnosis, it leads to improved patient outcomes and satisfaction both conservatively and surgically.