Presentation
Left axillary lump.
Patient Data
A large intramuscular lesion is seen in the left axillary region, seen insinuating between the scapula and the posterolateral aspect of the thoracic wall. It measures 11 x 8.7 x 12 cm in AP, SS, and CC dimensions. It displays homogeneous high T1, and high T2 signals with complete homogenous suppression on T2 STIR, consistent with its fatty nature.
It has a smooth outline formed by a pseudocapsule of stretched muscle fibers of the subscapularis muscle.
- anterior relations: axillary neurovascular structures and pectoralis major muscle. The tendon of pectoralis minor is stretched at its anterosuperior surface
- posteriorly, scapula
- medially: lateral thoracic wall (ribs and lateral chest wall muscles)
- laterally: humeral head, glenohumeral joint, and axillary neurovascular bundle
- superiorly: coracoid process, clavicle, and pectoralis minor tendon
- inferiorly: axillary fossa containing neurovascular bundle and axillary fat
Features are in keeping with intramuscular lipoma of subscapularis muscle.
Case Discussion
The patient shows stable features of axillary lipomatous mass over one year (previous MRI not shown). The MRI features are consistent with an intramuscular lipoma involving the subscapularis muscle.
See a similar case for comparison (rID: 81620).