Presentation
Left shoulder swelling for 8 months with reduced range of movement. No pain or numbness.
Patient Data
Soft tissue mass with mass effect over the left chest wall and left supraclavicular region. No appreciable aggressive periosteal reaction or bony erosion onto adjacent bone, namely left scapula, left clavicle, left ribs and left humeral head.
No shoulder dislocation or subluxation.
A large infiltrative soft tissue mass with epicentered at the left supraclavicular region and left anterior chest wall. It shows isointensity on T1WI (relative to skeletal muscle) and hyperintensity on T2W. On post contrast, the mass enhances avidly with central non enhancing component which can represent necrosis. Hypointense bands within the mass and these bands lack prominent enhancement on the postcontrast images. These bands can represent collagenized bands.
Anteriorly, the mass infiltrates into the left pectoralis minor muscle. Medially, suspicious infiltration of the mass into the upper three intercostal muscles and adjacent serratus anterior muscles. Superomedially, the mass extends to involve the division and cords of left brachial plexus by infiltrating between left anterior and middle scalene muscles. Posterior the mass infiltrates the left subscapularis, supraspinatus, infraspinatus, teres minor, teres major muscles.
No obvious cortical erosion or changes in the bone marrow signal within the left scapula bone and humerus.
On coronal view post contrast T1W, presence of fascial tail sign (linear/tapered extension of soft tissue tumors along the fascia).
The mass encases the left subclavian artery and vein, left axillary artery and vein.
Multiple enlarged left axillary and supraclavicular lymph nodes.
A small lytic bony lesion seen at the body of left scapula without bony expansion. The tumor is predominantly soft tissue tumor rather than aggressive bone tumor, such as Ewing sarcoma or osteosarcoma.
Case Discussion
Core biopsy performed for this mass proved to be desmoid fibromatosis. This MRI showed the widespread local infiltrative nature of this tumor into the surrounding skeletal muscles, encasement of the vessels and left brachial plexus complicated the success rate for complete excision of this tumor.
Desmoid fibromatosis can occur at abdominal, intra-abdominal and extraabdominal locations. Extraabdominal fibromatosis frequently occurs in the limbs, followed by the head and neck region.
Aggressive fibromatosis usually originates from muscular connective tissues, aponeurosis or fascia.
They are considered benign but locally aggressive tumors with no metastatic affinity.
Given infiltrative aggressive nature, the common problem is incomplete surgical resection, resulting in high local recurrence rates.
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