Superficial Infrapatellar Bursitis

Oval cystic lesion anterior to the distal aspect of the patellar tendon. It follows fluid signal intensity on all pulse sequences.
Bursitis is inflammation of the synovial lining of a bursa with effusion.
Patellar (anterior knee) bursitis may be:
1-Prepatellar: anterior to the inferior pole of patella and proximal patellar tendon,
2-Superficial infrapatellar: anterior to the distal aspect of patellar tendon and
3-Deep infrapatellar: between patellar tendon and anterior aspect of proximal tibia.
Patellar bursitis is found in occupations or activities requiring large amount of kneeling e.g. housemaids, clergy, carpet layers and wrestlers.
Most common clinical presentation is anterior knee pain with or without mass.
Reference: Stoller et al; 2004; Diagnostic imaging: Orthopaedics. Amirsys.
Credit: Dr Ahmed Haroun
http://www.radpod.org