Hoffa fat pad herniation

Case contributed by Ammar Haouimi
Diagnosis almost certain


Painless soft mass at the anterolateral aspect of right knee visible mainly on a flexed knee.

Patient Data

Age: 45 years
Gender: Female

There is a soft tissue mass of the anterolateral aspect of the knee measuring 23 x 20 x 13 mm, eliciting an isosignal to the Hoffa fat pad on all sequences. The axial sequences show a focal defect in the lateral patellar retinaculum through which the Hoffa fat pad is herniated. 

Case Discussion

MRI features of Hoffa fat pad herniation.

Hoffa fat pad herniation occurs in preschool-aged and young children and defined as herniation of infrapatellar fat through a defect in the lateral retinaculum. 

In a recent study, it was suggested that it may be considered as a normal variant rather than a pathologic change 1.


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