Introduction: The accessory soleus muscle (also known as the supernumerary soleus or soleus secundus) is an uncommon congenital anatomical. The presence of this muscle is generally asymptomatic. In cases of symptomatic accessory soleus muscle, it manifests with painful swelling of the posteromedial region of the ankle. To the best of our knowledge, partial or complete accessory soleus tendon tears were reported in literature in only three cases; all of them were diagnosed with magnetic resonance imaging (MRI) examination while only one was diagnosed with both ultrasound (US) and MRI.
Case Report: We presented a case of a 63-year-old Caucasian woman presented to our emergency department with severe pain in the posteromedial region of her right ankle. US and MRI of the calf and ankle were performed and a complete tear of the right accessory soleus tendon with fluid gap and myotendinous retraction was diagnosed.
Conclusion: An accessory soleus muscle partial or complete tears are very uncommon injuries. This condition can mimic many other pathologies, and therefore, radiologists should know the physiological and pathological imaging findings for a correct interpretation of ankle injuries, avoiding misinterpretations.